Cognitive level

Description

Paper 2
(Chemistry)

1

Remembering/Recall

15%

2

Understanding/Comprehension

40%

3

Applying and analysing

35%

4

Evaluating and creating (synthesis)

10%

Chemistry 

• 10 multiple-choice questions – 20 marks
• Structured questions – 130 marks 

Question word

What is required of you

Analyse

Separate, examine and interpret

Calculate

This means a numerical answer is required – in general, you should show your working, especially where two or more steps are involved

Classify

Group things based on common characteristics

Compare

Point out or show both similarities and differences between things, concepts or phenomena

Define

Give a clear meaning

Describe

State in words (using diagrams where appropriate) the main points of a structure/process/phenomenon/ investigation

Determine

To calculate something, or to discover the answer by examining evidence

Differentiate

Use differences to qualify categories

Discuss

Consider all information and reach a conclusion

Explain

Make clear; interpret and spell out

Identify

Name the essential characteristics PAY SPECIAL ATTENTION

Label

Identify on a diagram or drawing

List

Write a list of items, with no additional detail

Mention

Refer to relevant points

Name

Give the name (proper noun) of something

State

Write down information without discussion

Suggest

Offer an explanation or a solution

Tabulate

Draw a table and indicate the answers as direct pairs

(adj)

adjective: describing word such as “big”

(adv)

adverb: describing word for verbs, such as “fast”

(prep)

preposition: a word describing a position, such as “on”, “at”

(sing)

singular: one of

(pl)

plural: more than one of

(abbr)

abbreviation

General terms

Term

Meaning

A

abbreviate

(v). Make shorter.

abundant

(adj). Having plenty of something.

accept

(v). Agree to receive something; say yes to; believe; tolerate something.

account for

(v). Explain why.

adjacent

(adj). Next to something.

affect

(v). Make a difference to; touch the feelings of. Do not confuse with effect. See effect.

analyse

(v). Examine something in detail.

ante-

(prep). Before (e.g., ante-natal – before birth)

anti-

(prep). Against (e.g., anti- apartheid – against apartheid).

apparent

(adj). Clearly visible; the way something seems to be or the way it appears.

appear

(v). Come into sight; seem to be.

approximate

(v. & adj.). Come close to (v); roughly, almost, not perfectly accurate, close but not exact. The verb is pronounced “approxi-mayt” and the adjective is pronounced “approxi-mitt”.

aquatic

(adj). Growing or living near or in water.

arbitrary

(adj). Based on random choice; unrestrained and autocratic.

C

category

(n). Class or group of things.

cause

(v). Make something happen.

cause

(n). The person or thing that makes something happen; an aim or movement to which a person is committed.

causality

(n). Someone or something responsible for a result.

collide

(v). To crash into; to hit.

complex

(adj). Consisting of many different parts; not easy to understand (n) a group or system of things connected in a complicated way.

component

(n). A part.

compose

(v). To make up from parts.

composite

(n). Something made up of parts; (adj) made up of several parts.

condition

(n). The state something is in; the situation that must exist before something else is possible.

conjunction

(n). When two or more things come together at the same point; in grammar, a part of speech that connects words, sentences, phrases or clauses, e.g.: “and”

consider

(v). Think about.

contrast

(v). Show the difference between;

(n). something that is very different from what it is being compared with.

conversely

(adv). The opposite of.

counteract

(v). Act against something in order to stop it.

D

data (pl),

datum (sing)

(n). Information given or found.

deduce

(v). To work something out by reasoning.

deduction

(n). Conclusion or idea that someone has worked out.

define

(v). Give the meaning of a word or words.

definition

(n). The meaning of a word or words.

deliver

(v). To bring and hand over.

denote

(v). To refer to or mean something.

determine

(v). Work out, usually by experiment or calculation.

discreet

(adj). Careful, polite.

discrete

(adj). Single, separate, distinct, a part.

E

effect

(n). Result.

effect

(v). Carry out, do, enact.

eject

(v). Force or throw something or someone out violently or suddenly.

elapse

(v). Pass by or finish, e.g., time.

establish

(v). Show or prove, set up or create.

exceed

(v). Go beyond.

excess

(n). More than necessary.

excluding

(prep). Not including.

exclusive

(adj). Excluding or not admitting other things; reserved for one particular group or person.

exemplar

(n). A good or typical example.

exempt

(v). To free from a duty.

exempt

(adj). Be freed from a duty.

exemption

(n). Being freed from an obligation.

exhibit

(v). To show or display.

exhibit

(n). A part of an exhibition.

expel

(v). Force someone or something to leave a place. Eject.

extent

(n). The area covered by something.

F

factor

(n). A circumstance, fact or influence that contributes to a result; a component or part.

factory

(n). A place where goods are made or put together from parts.

find

(v). Discover or locate.

find

(n). Results of a search or discovery.

finding

(n). Information discovered as the result of an inquiry.

fixed

(adj). Not able to move, attached; or repaired, not broken.

format

(n). Layout or pattern; the way something is laid out.

G

global

(adj). Found all over the world (globe).

H

hazard

(n). Something dangerous.

heterogeneous

(adj). Made up of many different parts.

homogeneous

(adj). Uniform, made up of the same types of parts.

hypothesis

(n). A theory or proposed explanation.

hypothetical

(adj). Theoretical or tentative; waiting for further evidence.

I

identify

(v). Recognise or point out.

illustrate

(v). Give an example to show what is meant; draw.

impair

(v). Weaken or damage.

imply

(v). Suggest without directly saying what is meant.

indicate

(v). Point out or show.

initial

(n). First.

initiation

(n). The action of beginning something; the action of admitting somebody into a group or organisation.

insufficient

(adj). Not enough.

interchange-

(adj). Can be swapped or

able

exchanged for each other.

investigate

(v). Carry out research or a study.

issues

(v). Comes out of.

issues

(n). An important problem or a topic for debate.

M

macroscopic

(adj). Visible without being made bigger.

manipulate

(v). Handle or control (a thing or a person).

microscopic

(adj). Very small, not visible without being made bigger.

motivate

(v). Give someone a reason for doing something.

multiple

(adj). Many.

N

negligible

(adj). Small and insignificant; can be ignored. From “neglect” (ignore).

numerical

(adj). Relating to or expressed as a number or numbers.

numerous

(adj). Many.

O

observe

(v). Look at; watch carefully.

obtain

(v). Get.

occur

(v). Happen.

operate

(v). Work; drive; control.

optimal

(adj). Best; most favourable.

optimum

(adj). Best; (n) the most

favourable situation for growth or success.

overabundance

(n). More than enough; too much.

P

phenomenon

(n). A fact or situation that is seen to exist or happen.

phenomena

(n). Plural of phenomenon.

prefix

(n). Part of a word that is attached to the beginning of many different words, changing their meaning, e.g., prehistoric – before written records were kept.

prepare

(v). Make ready before an event; set things up.

principal

(n). Head of a school.

principal

(adj). Main or most important.

principle

(n). A basic truth that guides the way a person behaves.

provide

(v). Make available for use; supply.

Q

quality

(n). The standard of something compared to other similar things; a characteristic of someone or something.

R

reciprocal

(adj). Given or done in return.

record

(v). Make a note of something in order to refer to it later (pronounced ree-cord).

record

(n). A note made in order to refer to it later; evidence of something; a copy of something (pronounced rec-cord.

relative

(adj). Considered in relation to something else; compared to.

relative

(n). A family member.

represent

(v). Be appointed to act or speak for someone; amount to.

resolve

(v). Finalise something or make it clear; bring something to a conclusion.

respect

(v). Admire something or someone; consider the needs or feelings of another person.

respectively

(adj). In regards to each other, in relation to items listed in the same order.

S

simultaneously

(adv). At the same time.

site

(n). Place.

suffice

(v). Be enough.

surplus

(adj). More than is needed.

survey

(n). A general view, examination, or description of someone or something.

survey

(v). Look closely at or examine; consider a wide range of opinions or options.

T

tendency

(n). An inclination to do something in a particular way; a habit.

tertiary

(adj). Third level.

U

uniform

(n). Standardised clothing.

uniform

(adj). Remaining all the same at all times; unchanging.

V

verify

(v). Show to be true; check for truth; confirm.

vice versa

(adv). The other way round.

versus

(prep). Against. Abbreviated “vs” and sometimes “v”.

absorption

(n). To take into; the process of

taking something in.

account

(n. & v.). Finance: A record of

income and expenditure. To

explain (v), e.g. “Account for why

the sky is blue”.

acetic

(adj). Pertaining to vinegar; an

organic molecule containing two

carbons. See organic, eth- for

more.

acetone

(n). Propanone. CH₃COCH₃; the

ketone of acetic acid. See ketone

for more.

acetylene

(n). Ethyne, C₂H₂. Used in welding

torches (blowtorches). See also

alkene.

acid

(n). A proton donor or substance

that ionises into H+ or H₃O+ when

dissolved in water; sour-tasting

substance; corrosive; pH below 7.

See also base and alkali.

acidified

(adj). To have been made acidic.

acidity

(n). How acid something is.

activated

(adj). Made to function. Chemistry:

something moved into an unstable

higher-energy level or state.

Usually “activated complex”, the

combination of reactants just

before they turn into products. See

also reactant, reagent, product.

activation

(n). The process of activating

something. “Activation energy”,

the required energy to create an

activated complex.

aerosol

(n). A solution of substances in air or

other gas, e.g. as in an aerosol can.

affinity

(n). A liking for something;

an attraction to something; a

tendency to react with something

(chemistry). See also paraffin.

alcohol

(n). In common usage, ethanol

C₂H₅OH. Technically, any organic

substance or molecule containing

an -OH group. See organic.

aldehyde

(n). Any organic molecule containing

-CHO, formed by oxidising alcohols.

See alcohol and organic.

algae

(n). Adjective: algal (pertaining to

algae); an aquatic plant (lives in

water), which lacks leaves, stems,

roots.

algebra

(n). A mathematical system

where unknown quantities are

represented by letters, which

can be used to perform complex

calculations through certain rules.

alkali

(n). See base.

alkane

(n). An organic molecule or

compound or substance which

contains only single bonds

between carbons. See organic.

alkene

(n). An unsaturated organic

molecule, compound or substance,

which contains at least one double

bond between carbons. See

organic and unsaturated.

alkyl

(n). A prefix (word part) which shows

that the word after it has an alkane

group attached to it, by removing

one hydrogen from the alkane.

alkyne

(n). An unsaturated organic

molecule, compound or substance,

which contains at least one triple

bond between carbons. See

organic and unsaturated.

amalgam

(n). General use: a mixture. In

chemistry, specifically a mercury

alloy.

amide

(n). An organic compound

containing the group -C(O)NH₂; an

inorganic compound containing

the group NH₂^–.

amine

(n). The same as an amide except

the -NH₂ can be attached to

anything, and does not have the

CO group shown above.

ammonia

(n). NH₃.

ammonium

(adj). NH₄+, found as a cation or as

part of a salt. See salt and cation.

amphiprotic

(n). See ampholyte.

ampholyte

(n). A substance that can act as an

acid or base. See acid, base.

anions

(n). A negative ion. See cation, ion.

anode

(n). The negative electrode of

a cell or current supplier; the

positive electrode of an electrolytic

system; attracts negative ions. See

electrode, cathode.

antacid

(n). A substance used to neutralise

(react with) acid. E.g. chalk. See

acid, neutralise.

apparatus

(n). Equipment; parts of a scientific experiment.

aqueous

(n). Dissolved in water.

Arrhenius

(n). Arrhenius’ theory of acids and bases: That acids produce H+ or H₃O+ in water, and bases produce OH–. See Brønsted-Lowry.

asbestos

(n). A fireproof fibrous substance containing silicon used for fireproofing.

asbestosis

(n). A lung disease caused by inhaling asbestos fibres, can lead to cancer.

atm

(n). Abbreviation: atmospheres of pressure (1 atm = 101,3 kPa). The pressure of the air at sea level. Same as “bar” (barometric pressure).

ATM

(n). Abbreviation: automatic teller machine.

atmosphere

(n). The air or the gases surrounding a planet; the sky; as a unit of measurement, see atm.

atmospheric

(adj). To do with the atmosphere.

atom

(n). The smallest unit of a chemical element, which, if broken down further, no longer behaves in the same way chemically. Consists of a nucleus or centre part which is positively charged, and an electron cloud (negatively charged) which surrounds the nucleus. See nuclear.

attract

(v). To bring something closer.

average

(n). Mathematics: The sum of parts divided by the quantity of parts. In common use: neither very good, strong, etc., but also neither very weak, bad, etc; the middle. In Physical Science and Mathematics: if you are asked to find the average, you always have to calculate it using the information you have. For example, the average of (1;2;3) is 2, because (1+2+3)/3 = 2. See also mean, median and mode.

avogadro (constant or number)

(n). 6,023 × 1023 particles; one mole. See mole and mol.

axis (sing), axes (pl, pronounced “akseez”)

(n). A line along which points can be plotted (placed), showing how far they are from a central point, called the origin. See origin. “Vertical axis” or “y-axis” refers to how high up a point is above the origin (or how far below). “Horizontal axis” or “x-axis” refers to how far left or right a point is away from the origin.

B

bakelite

(n). A type of hard, brittle plastic

that can’t melt once it has set

or taken shape (thermosetting),

made from phenol C₆H₅OH, and

formaldehyde (methanal), CH₂O.

balance

(v. & n.). To make two things equal

(v); a scale to weigh objects (n).

Chemistry: to compare two sides

of a chemical equation and make

sure that there are the same

numbers of atoms on both sides.

base

(n). A proton acceptor, or substance

that ionises into OH– when

dissolved in water; a bitter-tasting

substance, corrosive, pH above 7.

See also acid. Do not confuse with

common everyday use, meaning

“the bottom” or “low”.

basic

(n). Bitter or made of a base. Do not

confuse with popular use, meaning

“low” or “simple” or “crude”.

battery

(n). A collection of cells connected

in series (end-to-end). See cell. In

common use, “battery” is used to

mean the same as “cell” (e.g. a

penlight or AA cell), but this use is

incorrect except for a car battery,

which consists of a series of cells.

benzoic

(adj). Contains benzene or a

benzene ring.

bi-

(prefix). Two.

bicarbonate

(n). Any salt containing the ion

-HCO –. So called because the

3

carbonate (CO₃2–) attaches to

another ion and the hydrogen

(two bonds). The name “hydrogen

carbonate” is now preferred.

biodegradable

(adj). Can be broken down by

natural processes e.g. involving

bacteria, moulds, fungus, etc.

biodiesel

(n). Diesel (a type of petrol) made

from plants rather than fossil fuels

(coal, oil).

BODMAS

(abbr). Brackets, of/orders

(powers, squares, etc), division,

multiplication, addition, subtraction.

A mnemonic (reminder) of the

correct order in which to do

mathematical operations.

boil

(v). Physics: to cause a liquid’s

vapour pressure to exceed

the pressure of the gas in the

container, usually by heating it,

but it can be done by lowering

the pressure of the gas in the

container, too. See vapour

pressure. In common usage, to

make a liquid hot until it bubbles.

bond

(n). A connection. In physics and

chemistry, between atoms and

molecules.

breadth

(n). How wide something is. From

the word “broad”.

brine

(n). A saturated salt solution (a

mixture of water and salt which

can’t dissolve any more salt).

bromide

(n). Something containing bromine,

usually one ion. See ion.

bromo-

(prefix). Something containing

bromine.

bromothymol

(n). A type of acid-base indicator

(blue)

used to tell whether something

is an acid or base. Turns blue (in

base) or yellow (in acid).

Brønsted-Lowry

(n). A theory of acids and bases

which says that acids are proton

donors (they give away protons),

and bases are proton acceptors

(they take protons). Since H+ is

just a proton, this does not mean

something different from the

Arrhenius theory that an acid is a

substance that dissolves into H+ in

water. See proton, Arrhenius.

but-

(prefix). Four carbons. Pronounced

“beaut”. E.g. butane is a four-

carbon alkane.

C

calibrate

(v). To adjust a measuring tool

or measurement against a

known accurate measurement to

ensure that the measuring tool or

measurement is accurate; to check

a measurement or measuring

tool’s accuracy; to mark with

accurate measurements using a

standard scale like cm, mm, mℓ,

etc. Common use: to assess or

evaluate carefully.

carbohydrate

(n). Organic compounds containing

carbon and hydrogen, occurring

in foods and living tissues and

including sugars, starch, and

cellulose. They contain hydrogen

and oxygen in the same ratio

as water (2:1). Not the same

as hydrocarbons, which are any

substances containing mostly

hydrogen and carbon.

carbonate

(n). -CO₃^2–

carbonic

(adj). Anything containing carbon,

or more specifically, CO₂

carbonyl

(adj). Containing double bonded

carbon and oxygen: =C=O.

carboxyl

(adj). Containing -COOH.

carboxylic

(adj). Carboxyl-containing.

Cartesian

(adj). Anything believed or

proposed by Rene Descartes.

In particular, the x-and-y axis

coordinate system.

catalyst

(n). A substance that alters the

rate of a chemical reaction without

itself being consumed in the

reaction. Without qualification, or

as “positive catalyst”, something

that starts or speeds up a reaction.

A “negative” catalyst slows down a

reaction.

catalytic

(n). Containing or using a catalyst.

cathode

(n). The positive electrode of a cell

or current supplier; the negative

electrode of an electrolytic

system; attracts positive ions. See

electrode, anode, ion.

cathodic

(adj). Involving a cathode. Cathodic

protection: To use a more reactive

metal to protect a less reactive

metal from oxidation. See anode,

cathode, oxidise.

cation

(n). A positively charged ion. See

anion, ion.

caustic

(adj). Basic; a base.

cell

(n). An apparatus that generates

electricity using electrochemistry.

An AA or Penlight battery, as it is

commonly called, is a cell. A car

battery consists of a number of

cells inside a single container.

CFC

(n). A chlorofluorocarbon. A

substance containing carbon,

chlorine and fluorine. Responsible

for breaking down ozone (O₃) which

protects us from too much UV

radiation from the sun.

chain

(n). Chemistry: a long series of

atoms bonded together, usually

carbon.

charge

(n). Chemistry: having too

many or too few electrons

(most commonly), resulting in

a substance ionising. A positive

charge results from too few

electrons, and a negative charge

from too many electrons. Physics:

a basic feature of all physical

electromagnetic particles, except,

e.g. neutrons and photons, which

have zero charge. All protons have

a positive charge, all electrons

have a negative charge.

chart

(v). To draw a diagram comparing

values on Cartesian axes.

Le Châtelier’s

(n). That in reversible reactions,

Principle

chemical systems will favour the

forward or reverse reaction to

minimise the change imposed

on the system. If a chemical

equilibrium is disturbed by

changing the conditions, the

position of equilibrium moves to

counteract the change.

chloro-

(prefix). Containing chlorine.

chlorofluoro-

See CFC.

carbons

chloroform

(n). CHCℓ₂. A liquid formerly used

as an anaesthetic.

chlorophyll

(n). A green substance found

in plants which enables

photosynthesis (broadly,

generating food from CO₂). See

photosynthesis.

coefficient

(n). A constant value placed

next to an algebraic symbol as a

multiplier. Same as constant (see

below). Or: a multiplier or factor

that measures a property, e.g.

coefficient of friction.

combustion

(n). The process of burning, usually

in oxygen. Rapid oxidation.

completion

(n). Chemistry: when a reaction

no longer proceeds (continues)

because it has run out of one

or more of the reactants. See

reactant, reaction.

complex

(n). See activated.

(activated)

compound

(n). A substance made up of

molecules consisting of more

than one different type of atom,

chemically bonded in a constant

ratio. E.g. Water (H₂O) is a

compound, but Sulphur powder

(S) is not. In a compound, the

original chemicals (reactants) have

reacted or merged to form a new

substance. Compare to mixture.

compressed

(adj). Subjected to pressure,

squashed.

concentration

(n). The number of moles of

substance per unit volume.

See mol, moles. How “strong” a

solution is. See solution.

condensation

(n). When a vapour or gas cools

down and starts to collect into

larger droplets; changing phase

from vapour or gas to liquid.

Condensation reaction: to produce

a larger molecule from two smaller

ones.

conditions

(n). Physics and Chemistry: how

(STP)

the environment is: temperature

and pressure. STP (Standard

Temperature and Pressure is 25°C

and 1 atm).

conjugate

(n). To join together. Chemistry: two

things that belong together, e.g.

conjugate acid-base pairs.

conservation

(n). A law which describes

something that does not change.

E.g. the conservation of matter-

energy says that matter-energy

cannot be created or destroyed,

only transformed from one form

into another. There are a number

of other conservations, e.g.

momentum and torque.

constant

(n). See coefficient. Means

“unchanging”.

contaminate

(v). Chemistry: to introduce

impurities or other substances

which are not meant to be part of

a reaction.

control

(n. and v.). To ensure something

does not change without

being allowed to do so (v);

an experimental situation to

which nothing is done, in order

to compare to a separate

experimental situation, called the

‘experiment’, in which a change

is attempted. The control is then

compared to the experiment to see

if a change happened.

control variable

(n). A variable that is held constant

in order to discover the relationship

between two other variables.

“Control variable” must not be

confused with “controlled variable”

(see independent variable).

coordinate

(n). The x or y location of a point on

a Cartesian graph, given as an x or

y value. Coordinates (pl) are given

as an ordered pair (x, y).

correlate

(v). To see or observe a

relationship between two things,

without showing that one causes

the other.

correlation

(n). That there is a relationship

between two things, without

showing that one causes the other.

correspond

(v). To pair things off in a

correlational relationship. For two

things to agree or match. E.g. A

corresponds to 1, B corresponds to

2, C corresponds to 3, etc.

corrode

(v). Chemistry: to destroy by

gradual chemical action. Usually

refers to acidic action. Compare

to erode. General use: to destroy

gradually.

corroding

(adj). A process or substance

that corrodes; to be subject to

corrosion.

corrosion

(n). To corrode.

corrosive

(adj). To be capable of corroding

something.

counteract

(v). Oppose or resist.

covalent

(adj). Chemistry: a bond which

results from sharing electrons

between atoms. Compare ionic

bond.

cracking

(n). A process of breaking a

complex organic molecule into

simpler parts using heat and

pressure.

cubed

(adj). The power of three;

multiplied by itself three times.

cubic

(adj). Shaped like a cube; having

been multiplied by itself three

times.

current

(n). Flowing electrons.

D

decompose

(v). To break down into

components.

degradable

(adj). Capable of breaking down or

being broken down.

dehydrating

(adj). To remove water from. A

(agent)

“dehydrating agent” is a substance

which can remove water from

another substance. E.g. H₂SO₄,

ethanol.

dehydration

(n). The process of removing water

from a substance.

dehydrogena-

(n). The process of removing

tion

hydrogen from a substance.

dehydrohalo-

(n). To remove hydrogen and a

genation

halogen from a substance. See

halogen.

denominator

(n). See divisor. In popular speech:

a common factor.

depend

(v). To be controlled or determined

by something; to require something

to happen or exist first.

dependent

(adj/n). A variable whose value

(variable)

depends on another; the thing

that comes out of an experiment,

the effect; the results. See also

independent variable and control

variable. The dependent variable

has values that depend on the

independent variable, and we plot

it on the vertical axis.

depleted

(adj). Having been used up; run

out of.

deposit

(n). Finance: to place money into

an account. Physical Science: to

cover a surface of one substance

with another substance, e.g. metal

plating on an electrode.

determine(s)

(v). To cause; to ensure that; to set

(causation)

up so that; to find out the cause of.

di-

(prefix). Two.

diamine

(n). A substance containing two

amine groups. See amine.

diammonium

(n). Having two ammonium (NH₄)

groups. See ammonium.

diaphragm

(n). A thin sheet of any substance

covering a gap. Biology: the muscle

below the lungs which moves to

cause breathing. Electrochemistry:

a thin sheet inside a cell which

separates the electrodes. It is

porous and allows solutions

containing ions through, but serves

to separate gas products.

difference

(n). Mathematics: subtraction.

Informally: a dissimilarity. How

things are not the same.

dilute

(adj. & v). To lower the

concentration of a solution. See

solution and concentration (v):

a solution which has had its

concentration lowered (adj).

dilution

(n). The opposite of concentration;

how low a concentration is,

measured in mol/dm3; the process

of diluting.

dimer

(n). A molecule made of two

identical parts. See also polymer.

diode

(n). A semiconductor device with

two terminals (electrodes), usually

allowing current to flow in one

direction only.

diol

(n). A molecule with two alcohol/

hydroxyl (OH) groups.

dipole

(n). A polarised molecule with a

distinctly positive and distinctly

negatively-charged end.

diprotic

(n). Having two protons.

displace

(v). To move or relocate something.

dissipate

(v). To disperse or scatter (e.g.

gas). Thermodynamics (Energy):

to cause energy to be lost as heat.

Popular use: to disappear.

dissociate

(v). To break apart; to no longer be

associated with.

dissolve

(v). To break up into ions within a

solution (usually water); to mix a

solid (usually powder) into a liquid,

to form a solution. See solution,

ion. Alternative popular use: to

bring to an end.

distil(l)

(v). To purify through repeated

heating of a liquid and collection

of condensation. The heating

process causes the liquid to form

gas or vapour, which condenses

on the side of the heating vessel

(container) or an exit tube, leaving

impurities behind in the heating

vessel.

distribution

(n). How something is spread

out. Mathematics: the range and

variety of numbers as shown on a

graph.

disturb

(v). Chemistry: to mix or stir a liquid

or solution; to shake it up.

divisor

(n). The number below the line

in a fraction; the number that is

dividing the other number above

the fraction line. See numerator,

denominator.

domain

(n). The possible range of x-values

for a graph of a function. See

range.

durable

(adj). Tough; something that can

endure.

dynamic

(adj). Changing often. Relating

to forces that produce motion.

Opposite of static. See static and

electrostatic.

E

ecosystem

(n). An integrated, complex,

interacting, mutually dependent

living system or environment.

electric

(adj). Containing electricity

(electrons).

electro-

(adj). Where chemical reactions

chemical

cause the release of electrons,

usually into a circuit. General use:

anything relating to electrical and

chemical phenomena.

electrode

(n). General use: the point where

electrons enter or exit a power

source or a circuit. Specifically

(Electrochemistry): Part of a circuit

dipped into a solution to receive or

release electrons. See anode and

cathode.

electrolysis

(n). The splitting of a chemical

into ions. (The chemical is usually

dissolved in water or another

solution.) It is done by means of

electricity. See electrochemical.

electrolyte

(n). A substance (usually liquid

or gel solution) which contains

a compound that will be split by

electricity. Ionisable solutions or

components.

electromotive

(adj). Usually electromotive force

or emf. The potential difference

caused by electromagnetism,

which causes current to flow.

Producing a current with

electromagnetism. See emf.

electron

(n). A fundamental physical

particle bearing a negative charge,

weighing approximately 9 × 10−28g,

which is found around atomic

nuclei in areas called ‘orbitals’.

Responsible for electricity and

chemical reactions. Symbol e–. See

proton, nucleus.

electroplate

(v). To cover a surface of a less

valuable substance with a more

valuable metal, using electrolysis.

element

(n). Mathematics: part of a set

of numbers. Physics: a pure

substance made only of atoms of

one type, with the same number

of protons in each nucleus. An

element cannot be broken down

further without losing its chemical

properties. Each element has a

unique atomic number which is the

number of protons in the nucleus.

See nucleus, atom, isotope.

Popular use: part of.

eliminate

(v). To remove or get rid of.

Mathematics: to cancel a factor

out of one side of an equation by

dividing by that factor throughout,

or by substituting in another

formula or value that is equal.

Chemistry: to produce a smaller

substance as a by-product

from reacting more complex

substances, usually water or CO₂;

in the sense of: to remove those

molecules from the reaction.

emf

(abbr). Same as electromotive

force. Always written in lowercase

(small letters).

emission

(n). Something released, e.g. gas,

light, heat.

emit

(v). To release.

empirical

(adj). Relating to the senses or to

things that you can see, touch,

taste, etc. Chemistry: empirical

formula: a formula giving the

proportions of the elements

present in a compound but not the

actual numbers or arrangement

of atoms; the lowest ratio of

elements without giving structure

or quantities.

emulsion

(n). Small particles or droplets of

a substance or liquid which do

not dissolve in a different liquid;

suspended or floating within that

liquid, e.g. to mix oil and water by

shaking them up.

endothermic

(adj). Taking in heat, ΔH > 0. See

enthalpy, exothermic.

energetic

(adj). Having a lot of energy;

performing a lot of work.

energy

(n). Work or the ability to do

work. There are various forms of

energy: motion (E_k), light energy

(photons), electrical energy, heat,

etc. Energy can neither be created

nor destroyed, but only converted

from one form to another. See

conservation.

enthalpy

(n). The total heat content of a

system, H, including the chemical

energy.

equilibria (pl),

(n). The state of being in balance.

equilibrium

Chemistry: when the forward

(sing)

reaction rate is equal to the

reverse reaction rate. See Le

Châtelier’s Principle.

erode

(v). To wear away by means of

friction (rubbing).

ester

(n). An organic compound

produced by bonding an alcohol

to a carboxylic (organic) acid,

by means of dehydration. See

carboxylic, organic, alcohol,

dehydration. Responsible for fruit

flavours and many pleasant odours

(smells).

esterfication

(n). The production of esters.

estimate

(n., v.). To give an approximate

value close to an actual value; an

imprecise calculation.

eth-

(prefix). Containing two carbons.

eutrophication

(n). Excess nutrients in water

causing excessive plant growth and

strangulation of a waterway.

evaporate

(v). To change phase of matter

from liquid to gas. Compare

sublimate and boil.

excited

(n). The state of being in a higher

energy level (higher than ground

state).

exo-

(prefix). Outside of.

exothermic

(adj). Giving off heat, ΔH < 0. See

enthalpy, endothermic.

exponent

(n). When a number is raised to a

power, i.e. multiplied by itself as

many times as shown in the power

(the small number up above the

base number). So, 23 means

2 × 2 × 2. See also cubed.

exponential

(adj). To multiply something many

times; a curve representing an

exponent.

extrapolation

(n). To extend the line of a graph

further, into values not empirically

documented, to project a future

event or result. In plain language:

to say what is going to happen

based on past results which were

obtained (gotten) by experiment

and measurement. If you have

a graph and have documented

certain results (e.g. change vs

time), and you draw the line further

in the same curve, to say what

future results you will get, that is

called ‘extrapolation’. See predict.

extrude,

(v., n.). To push something through

extrusion

a mould or shape, usually a liquid

or gel through a hole, to create a

new shape.

F

fahrenheit

(n). A temperature scale based

on human body temperature.

Water freezes at 32°F and boils

at 212°F under standard

conditions. The conversion

formula to centigrade/celcius is:

(˚F – 32) × 5/

9

= ˚C

favoured

(adj). Preferred. Chemistry: in a

chemical reaction, the direction of

the reaction after the equilibrium

is broken.

fermentation

(n). The conversion of a sugar or

carbohydrate to an alcohol, usually

by yeast or bacteria.

fertilisation

(n). The process of adding

nutrients to soil. Biology: the fusion

of male and female gametes (sex

cells) into a zygote (group of cells

that will become a foetus or other

living organism).

fertiliser

(n). A substance added to soil for

nutritional reasons.

fixation

(n). The process of fixing on

something or someone.

fixed

(n). The process of attaching one

(chemistry)

chemical or compound to another.

E.g. nitrogen fixing is the bonding

of free N₂ to organic chemicals.

fluid

(n). Any substance that can flow

and take the shape of a container;

liquid, some gels, and gas.

fluorescent

(n). Bright, colourful, due to

changes in energy levels of

electrons, as seen in fluorescent

tubes, ink, etc. See reflective.

formic

(prefix). Same as meth-. Contains

one carbon. From Latin “formica”:

ant, referring to formic acid, which

is found in an ant’s sting.

fraction

(n). Mathematics: Not a whole

number; a representation of a

division. A part. E.g. the third

fraction of two is 0,666 or ⅔.

meaning two divided into three

parts. Chemistry: a part of a

solution or mixture separated out

by distillation. See distil.

function

(n). Mathematics: when two

attributes or quantities correlate.

If y changes as x changes, then

y = f(x). See correlate, graph,

Cartesian, axis, coordinate. Also:

a relation with more than one

variable (mathematics). Chemistry:

functional group: part of a

molecule that gives the substance

its chemical properties in common

with other similar chemicals.

G

galvanic

(adj). Relating to currents caused

by a chemical reaction. See

electrochemistry.

galvanising

(n). To electroplate so as to protect,

e.g. cover iron with zinc to prevent

rust.

gas

(n). The third phase of matter.

When a solid is heated it turns into

liquid, and when a liquid is heated

it turns into gas.

gaseous

(adj). In a gas form.

gradient

(n). A slope. An increase or

decrease in a property or

measurement. Also the rate of such

a change. In the formula for a line

graph, y = mx + c, m is the gradient.

gradually

(adv). To change or move slowly.

graph

(n). A diagram representing

experimental or mathematical

values or results. See Cartesian.

graphic

(n., adj.). A diagram or graph

(n). Popular use: vivid or clear or

remarkable (adj.).

graphically

(adv). Using a diagram or graph.

Popular use: to explain very clearly.

groundwater

(n). Water held in the earth

(underground).

gypsum

(n). Calcium sulphate.

H

Haber (process)

(n). An industrial process to produce

ammonia from nitrogen and

hydrogen, using an iron catalyst at

high temperature and pressure.

haemoglobin

(n). A compound containing

iron, found in red blood cells,

responsible for carrying oxygen.

half-cell

(n). One of the sides of an

electrochemical cell; one of the

electrodes and the chemical

solution around it.

half-reaction

(n). The equation for the chemical

reaction occurring in a half-cell.

halide

(n). A compound containing a single

halogen, e.g. NaCℓ. See halogen.

halo-

(prefix). Containing a halogen. See

halogen.

haloalkane

(n). An alkane bonded to a

halogen. See halogen.

halogen

(n). Any of the elements fluorine

(F), chlorine (Cℓ), bromine (Br),

iodine (I), and astatine (At), in

group VIIA (17) of the periodic

table. They combine with metals to

produce salts. See salt.

halogenation

(n). Adding a halogen.

hardness

(n). (Water). Containing salts, usually

calcium carbonate. If water contains

too many such salts, soap does

not function properly and doesn’t

produce bubbles or foam. “Water’s

hardness is determined by the

concentration of multivalent cations

in the water. Multivalent cations are

cations (positively charged metal

complexes) with a charge greater

than 1+. Usually, the cations have

the charge of 2+. Common cations

found in hard water include Ca2+

and Mg2+.” (Wikipedia).

heat

(n). Physics: a measure of the

average kinetic energy of the

molecules or atoms in a substance;

enthalpy; the energy of an object

as molecular motion. Alternatively,

infra-red radiation (heat radiation)

coming off a body. See body.

homologous

(n). Belonging to the same group

of things; analogous. Biology:

a flipper is homologous with a

leg or arm. Chemistry (organic):

belonging to the same series of

molecules, e.g. alkanes: methane,

ethane, propane; having the same

functional group.

hydrate

(n). To add water to.

hydration

(n). Having had water added.

Some salts are hydrated, meaning

that they have a number of water

molecules bonded to them, which

can be removed by heat. Heating

a hydrated salt changes its colour

but not the chemical reactions it

will undergo. See salt.

hydrocarbon

(n). Any compound consisting

mainly of hydrogen and carbon.

Compare carbohydrate.

hydrochloric

(adj). Any chemical containing HCℓ.

hydrohalogen-

(n). Adding a hydrogen and halogen

ation

atom to a molecule.

hydrolysis

(n). Splitting by reacting with

water. Applies to salts and organic

chemicals. E.g. A haloalkane plus

water or a dilute NaOH gives an

alcohol and either a hydrohalide

or sodium salt. Dissolving a

salt in water can be considered

hydrolysis.

hydronium

(n). H

O+ ion.

3

hydroxide

(n). OH– ion. This usage applies

specifically to bases (see acid,

base). In organic molecules, OH– is

an alcohol functional group called

the hydroxyl group. See alcohol,

hydroxyl, diol.

hydroxyl

(n). See hydroxide.

hydroxylamine

(n). An amine with a hydroxyl

group.

I

ideal

(adj). Not as seen in real

life; theoretical. Ideal gas: a

hypothetical gas whose molecules

occupy negligible space and

have no interactions, and which

consequently obeys the gas laws

(PV = nRT) exactly.

ignition

(n). The start of a combustion

reaction. Common use: to start

a car (which has an internal

combustion engine). See engine,

combustion.

illuminate

(v). To explain or light up.

immerse

(v). To cover in liquid.

impair

(v). Prevent; hinder; slow down.

impure

(adj). Containing a variety of

additional chemicals in smaller

amounts in addition to the main

chemical.

incandescent

(adj). Giving off light as a result of

being heated.

independent

(n). The things that act as input

(variable)

to the experiment, the potential

causes. Also called the controlled

variable. The independent variable

is not changed by other factors, and

we plot it on the horizontal axis. See

control, dependent variable.

indicator

(n). Chemistry: a substance used

to check for pH levels, which

changes colour according to pH.

See acid, base, pH.

indigo

(n). The colour between violet and

blue; purplish-blue.

inert

(adj). Chemistry: a chemical or

element which does not react or is

difficult to cause to react, e.g. Ne,

Xe, He. N₂ is sometimes described

as inert but it’s not in the group of

Noble Gases. Common use: lazy,

unwilling to move.

inflammable

(adj). Same as flammable; easily

set on fire (combustion).

inhibitor

(n). Something that slows down or

prevents.

inorganic

(adj). Not containing carbon;

mineral. Exceptions are C, CO, CO₂,

which, whilst they contain carbon,

are not considered organic as they

can be produced during inorganic

chemical reactions.

insoluble

(adj). Not able to dissolve.

insufficient

(adj). Not enough.

interact

(v). To affect each other, to be

directly involved with or act on

each other.

intermediate

(adj). A state in between.

intermolecular

(adj). Between molecules. See

molecule, intramolecular.

intramolecular

(adj). Within or inside a molecule.

See molecule, intermolecular.

inversion

(n). Chemistry: turning something

upside down.

ion

(n). An atom or molecule or part of

a molecule which has an electrical

charge due to gaining or losing one

or more electrons.

ionic (bond)

(adj.). A bond in which electrons

have been transferred from one

side of the molecule to another

resulting in a cation and anion,

which then attract. E.g. NaCℓ.

ionisation

(n). The process of ionising. See

ionise.

ionise

(v). To turn into an ion. See ion.

irreversible

(adj). Cannot be reversed. Said

of certain chemical reactions,

in which case it specifically

means that the reaction does not

spontaneously reverse (not an

equilibrium reaction). The reaction

only proceeds in one direction.

Example: combustion.

isolate

(v). To separate from. Usual use

in Physical Science means to

separate one chemical from

another. Compare insulate, distil.

isomer

(n). A substance with the same

empirical formula but a different

structural formula. See empirical,

structural.

isotope

(n). An element which has a

different number of neutrons from

the usual number of neutrons in the

element. E.g. 12C has 6 protons and

6 neutrons, but 14C has 8 neutrons

and 6 protons, and is radioactive.

IUPAC

(abbr). International Union of Pure

and Applied Chemistry. Standardised

naming conventions for chemicals.

J

joule

(n). Unit of energy.

K

kelvin

(n). Unit of temperature, with

absolute zero being the point where

no molecular motion occurs, at

-273,15˚C. Hence, the freezing point

of water is 273,15 K. Note that there

is no degree sign before K.

ketone

(n). An organic compound with the

carbonyl group = C = O. Made by

oxidising secondary alcohols. E.g.

acetone.

L

law

(n). In Physical Science, a

formula or statement, deduced

(discovered) from observation

(watching). The formula or

statement will then predict that

under the same conditions the

same thing will always happen. E.g.

the first law of thermodynamics

says that matter and energy

cannot be destroyed, but only

changed from one form to another.

leach

(v). When a substance drains out

of soil, e.g. into rivers. Similar to

“leak”.

litmus

(n). A type of acid/base indicator.

See indicator. It is red when

exposed to acid and blue when

exposed to a base.

M

macromolecule

(n). A large molecule, usually a

polymer or protein.

macroscopic

(adj). Large enough to be visible

to the unaided human eye; big

enough to be seen.

magenta

(n). A bright purple/pink colour.

manipulate

(v). To change, or rearrange

something. Usually in Mathematics

it means to rearrange a formula to

solve for (to get) an answer.

material

(n). Any substance, not just cloth.

matter

(n). Substance; stuff. Opposite of

vacuum (nothing).

mean

(n). See average.

median

(n). Mathematics: the number in

the middle of a range of numbers

written out in a line or sequence.

metal

(n). A substance which is malleable

(can be hammered flat), is ductile

(can be drawn into a wire), which

conducts electricity and heat well

and which is reflective (most light

striking it is emitted again). Most

elements are metals except the

few on the right hand side of the

periodic table starting at Boron (B)

and running diagonally down to

Astatine (At).

meth-

(prefix). Having one carbon. See

formic.

methylated

(adj). Having had a single carbon

or methyl group added.

metric

(adj). A measurement system,

using a base of 10 (i.e. all the

units are divisible by 10). The USA

uses something known as the

Imperial system, which is not used

in science. The Imperial system is

based on 12. Examples: 2,54 cm

(metric) = 1 inch (imperial).

1 foot = 12 inches = approx.

30 cm; 1 metre = 100 cm. 1 Fl.Oz

(fluid ounce) = approx 30 mℓ.

microscopic

(adj). Too small to be seen by the

unaided human eye.

minimum

(n). The smallest amount possible.

mixture

(n). When you mix or combine

substances without them

undergoing a chemical reaction. In

other words, the substances mixed

stay separate (chemically) and do

not bond. Different to compound.

See compound, reaction.

modal

(adj). Pertaining to the mode, or

method. Can mean: about the

mathematical mode or about the

method used. See mode.

mode

(n). Mathematics: the most

common number in a series of

numbers. See also mean, median.

mol

(abbr). Mole.

molar

(adj). About a mole. See mole.

mole

(n). A unit describing an amount

of substance. 6,023 × 1023

molecules or atoms of the

substance.

E.g. 18 g of water is 1 mol of

water (H = 1, O = 16, H₂O = 18).

molecular

(adj). About molecules. See

molecule.

molecule

(n). The smallest amount of a

compound; a single particle

composed of the elements that

make up the compound. E.g. in

water, a single particle consisting

of two hydrogen atoms and one

oxygen atom.

mono-

(prefix). One.

monomer

(n). Part of a macromolecule; the

simplest repeating unit. Monomers

bond to form polymers. See

polymer, isomer.

monoprotic

(adj). Having one proton.

N

neutral

(adj). Chemistry: pH 7,0. Neither

acid nor base. E.g. water. In

common use: not biased. See bias.

neutralise

(v). To make something neutral; to

complete an acid/base titration.

neutron

(n). A subatomic particle with

no charge, mass approximately

the same as a proton, found in the

nucleus of an atom. Symbol n0.

If there are too many protons in

a nucleus, the substance will be

radioactive as it releases

alpha particles (helium nuclei,

2p+ + 2n0).

nitrate

(n). Containing NO −.

3

nitrite

(n). Containing NO −.

2

nomenclature

(n). A system of describing things;

a naming system, designed to

make a name unambiguous or

unique.

nonmetal

(n). Any of the elements that are

not metals, e.g. Boron (B), Silicon

(Si), Sulphur (S), Oxygen (O), etc.

nucleus (sing),

(n).The centre of something

nuclei (pl),

(generally), specifically the centre

nuclear (adj)

of an atom, consisting of at least

one proton (hydrogen), or two

protons and two neutrons (helium).

Plural nuclei is pronounced “noo-

klee-eye”.

numerator

(n). The opposite of a denominator;

the number on top in a fraction.

O

-oate

(suffix). An ester.

odour

(n). A smell.

optimal

(adj). Best, most.

organic

(adj). Containing carbon, except C,

CO, CO₂.

origin

(n). Mathematics: the centre of

a Cartesian coordinate system.

General use: the source of

anything, where it comes from.

outlier

(n). Statistics: a data point which

lies well outside the range of

related or nearby data points.

oxalic (acid)

(n). Ethanedioic acid; chem.

formula: (COOH)₂.

oxidation

(n). Specifically, adding an oxygen

atom to a molecule, but more

general use: losing electrons from

any substance in a redox reaction.

See redox.

oxide

(n). A compound containing

an oxygen atom, especially if it

previously did not contain one, e.g.

iron (metal), vs iron oxide (rust).

oxidise

(v). To add an oxygen or remove

electrons from a substance.

P

paraffin

(n). Any waxy organic substance,

previously the general name for

alkanes. Formula ranges from

^C20^H42 ^{to C}40^H82^.

parallel

(adj). Keeping an equal distance

along a length to another item

(line, object, figure). Mathematics:

two lines running alongside each

other which always keep an equal

distance between them.

particle

(n). Any small part, e.g. a proton,

an atom, a molecule.

pascal

(n). The unit of pressure,

abbreviated Pa, units: N/m2

pent-

(prefix). Five.

per

(prep). For every, in accordance

with. Chemistry: the maximum

amount of an element possible

for the number of bonds available.

See e.g. peroxide.

peroxide

(n). H₂O₂.

perpendicular

(adj). Normal; at right angles to

(90˚).

phase

(n). Time, period; a state of matter

(solid, liquid, gas); the relationship

in time between the cycles of a

system (such as an alternating

electric current or a light or sound

wave) and either a fixed reference

point or the states or cycles of

another system with which it

may or may not be synchronised

(simultaneous). I.e. if two systems

vibrate at the same time at the

same rate, they’re “in phase”.

photosynthesis

(n). The process of converting

CO₂ into carbohydrates using

atmospheric CO₂, chlorophyll, and

light.

pi

(n). π, the Greek letter p, the

ratio of the circumference of a

circle to its diameter. A constant

without units, value approximately

3,14159.

plastic

(n., adj.). An artificial substance

made from hydrocarbon polymers

which is often flexible and able to

be moulded and is often a poor

electrical conductor (n); flexible

(adj).

plot

(v). To place points on a Cartesian

coordinate system; to draw a

graph.

poly-

(prefix). Many.

polyester

(n). A polymer made from esters.

polymer

(n). A synthetic substance made

from many monomers (repeating

units). See monomer.

polymerisation

(n). Making a polymer.

polyprotic

(adj). Having many protons.

porous

(adj). Having many holes that allow

fluids through.

positive

(adj). Having many protons not

paired with electrons; a lack of

electrons.

potential

(n). Having the ability to do work, in

particular, E_p (potential energy, the

tendency to fall or start moving,

as in a spring), or emf (voltage).

General use: potential exists when

there is an energy difference

between two points, e.g. due to

gravity or electrical charge. In the

context of electricity, read it as

“voltage”.

precipitate

(n). Chemistry: A product of a

reaction that cannot dissolve in the

solution and settles at the bottom

of the reaction vessel (container).

predict

(v). General use: to foresee.

Physical Science: to state what will

happen, based on a law. See law.

pressure

(n). A continuous force exerted on

an object over a certain area, in

pascals, Pa. N/m2. See pascal.

product

(n). Chemistry: the substance or

compound made as a result of a

chemical reaction. See reaction.

Mathematics: the result of

multiplying two numbers.

project

(n. & v.). A project (n., pronounced

PRODJ-ekt) is a plan of action

or long-term activity intended to

produce something or reach a goal.

To project (v., pronounced prodj-

EKT), is to throw something, or to

guess or predict (a projection). To

project a result means to predict a

result. See extrapolate.

prop-

(prefix). Three carbons.

Pronounced “prope” (rhymes with

“rope”).

proportion

(n). To relate to something else

in a regular way, to be a part of

something in relation to its volume,

size, etc; to change as something

else changes. See correlate and

respectively.

protein

(n). A large, complex organic

molecule containing nitrogen,

usually making up structural

elements of living things (building

blocks of cells, antibodies, etc).

protolytic

(adj). Capable of removing a

proton; proton transfer. Compare

acid.

proton

(n). The positively-charged particle

that forms the centre of an atomic

nucleus, weighing 1 836 times as

much as an electron, but having

the same and opposite charge.

Symbol p+. See also nucleus,

neutron, electron.

pump

(n). A machine that uses energy

to transfer a fluid from one

place to another. In Biology one

finds cellular pumps, which are

biological machines for transferring

ions and nutrients.

pure

(adj). Containing only the

compound or element in question,

without any other compounds or

elements mixed in. See impure.

purification

(n). The process of removing

impurities. See distil.

Q

qualitative

(adj). Relating to the quality

or properties of something. A

qualitative analysis looks at

changes in properties like colour,

that can’t be put into numbers.

Often contrasted with quantitative.

quantitative

(adj). Relating to, or by comparison

to, quantities. Often contrasted

with qualitative. A quantitative

analysis is one in which you

compare numbers, values and

measurements.

quantity

(n). Amount; how much.

R

rancid

(n). Having an unpleasant smell due

to having started to ferment or rot,

usually said of meat, oil or butter.

random

(n). Unpredictable, having no cause

or no known cause. Done without

planning.

range

(n). Mathematics: the set of values

that can be supplied to a function.

The set of possible y-values in a

graph. See domain.

rate

(n). How often per second (or per

any other time period). Physics:

number of events per second; see

frequency.

ratio

(n). A fraction; how one number

relates to another number; exact

proportion. If there are five women

for every four men, the ratio of

women to men is 5:4, written

with a colon (:). This ratio can be

represented as the fraction 5/₄ or

1¼ or 1,25; or we can say that

there are 25% more women than

men.

react

(v). Chemistry: when two or more

elements or compounds are

brought into a mixture and form

chemical bonds, creating new

compounds.

reactant

(n). A chemical before it bonds with

another chemical. See reagent.

reaction

(n). Chemistry: The process

of reacting; a state in which

chemicals react. See endothermic

and exothermic. Physics (nuclear):

When a nucleus of an atom breaks

down and subsequently releases

energy and/or bonds with another

nucleus. In the first case, it is a

fission (splitting) reaction, in the

second case a fusion (joining)

reaction.

reactive

(adj). Tending to react easily.

reactivity

(n). How reactive a substance is

(unreactive or reactive).

reagent

(n). A reactant when it is still in its

bottle or container, before being

mixed.

redox

(abbr). Chemistry: reduction-

oxidation reaction; a chemical

reaction in which one substance

is reduced (gains electrons), and

another is oxidised (loses electrons).

See reduce, oxidise, anode, cathode,

electrode, electrochemistry.

reduce

(v). To make smaller. Chemistry: to

gain electrons (negative charges).

reflux

(n., v.). A substance that flows back

into its container after coming out.

Chemistry: the process of boiling a

liquid so that any vapour is liquefied

and returned to the stock (source).

refraction

(n). Bending light when it travels

from one medium (e.g. air) into

another medium (e.g. water or

glass). Changing the direction of

propagation of any wave as a result

of its travelling at different speeds at

different points along the wave front.

See Huygens’ principle, diffraction.

S

salt

(n). In common usage, NaCℓ.

Chemistry: any compound formed

from the reaction of an acid with

a base, with the hydrogen of the

acid replaced by a metal or other

cation. A non-metal ion bonded to

a metal ion.

saturated

(adj). Organic chemistry: Having

no available bonds or only single

bonds. Common use: cannot take

any more, usually said of a cloth

and liquid.

SI

(abbr). Système International. The

international system of metric

units used by scientists. See

metric, IUPAC.

simplify

(v). To make simpler. Mathematics:

to divide throughout by a common

factor (number or algebraic letter)

that will make the equation easier

to read and calculate.

slaked (lime)

(n). Calcium Hydroxide, Ca(OH)₂.

solubility

(n). How easily something dissolves

(mixes into a liquid).

soluble

(adj). See solubility.

solute

(n). The substance that you place

in a liquid (the solvent) so as to

dissolve it. E.g. salt. See solvent.

solution

(n). A mixture of a solute and a

solvent. A liquid which has had

something dissolved in it (mixed).

Mathematics: the step-by-step

displaying of calculations to

arrive at answers. Common use:

the answer to a problem, in the

sense of dissolving (removing) a

problem.

solvent

(n). The liquid that dissolves the

substance placed into it. E.g. water.

spectator

(n). Chemistry: a compound or

chemical which does not get

involved in a chemical reaction.

spontaneous

(adj). Randomly, without

provocation or cause or prior

planning.

stable

(adj). Chemistry and Nuclear

Physics: not likely to break down or

react further.

standardised

(adj). Chemistry: a solution of

known concentration, e.g. 1 molar

(1 mol/dm3).

steam

(n). Water vapour, microscopic

droplets of water. Not a gas, a

suspension of water droplets in air.

See suspension, gas, liquid, phase,

aerosol.

STP

(abbr). Standard temperature and

pressure; 101,3 kPa and 25˚C.

structural

(adj.). Pertaining to structure;

(isomer)

a series of molecules whose

structures are different but their

chemical or empirical formulae are

the same.

sublimate

(v). To change phase of matter

from solid straight to gas without

the intermediate phase of liquid.

See the case of dry ice (CO₂).

subscript

(n). A number placed below the

rest of the line, e.g. CO₂.

substance

(n). Matter. Physical things.

substituent

(n). Chemistry: an ion or functional

group or group of atoms that

replaces a hydrogen on an organic

molecule.

substitute

(v). To replace.

substitutents

(n). Something that gets replaced.

substitution

(n). The process of substituting.

Mathematics: to replace an

algebraic symbol in a formula with

a known value or another formula,

so as to simplify the calculation.

See simplify. Chemistry: to

cause a substituent to bond to a

substance.

superscript

(n). A number placed above the

rest of the line, e.g. πr2.

synthesis

(n). The process of

manufacturing (making)

something. Chemistry: to bond

smaller molecules together

to create a larger molecule,

e.g. methanol from CO and H .

Synthesis gas: a gas mixture ²

(e.g. CO, H₂), which when heated

produces a new compound, e.g.

methanol.

synthetic

(adj). Artificial, man-made.

system

(n). Any closely associated and

inter-related or inter-dependent

group of things; a set of things

working together. Chemistry: a

vessel (container) which contains a

chemical reaction.

T

terminal

(n). Final; end point.

termination

(n). Coming to an end.

tetra-

(prefix). Four.

theory

(n). A usually mathematical

representation of an explanation

for something in the sciences,

which does not depend on the

thing being explained. A theory

differs from a law in that theories

are prone to empirical (visible

or measurable) refutation

(rejection); meaning that they

can be discarded if evidence

comes in that they are wrong.

See law.

thermoplastic

(n). Chemistry: will melt if heated.

thermoset

(n). Once set into a shape it cannot

melt again.

thiosulphate

(n). A salt containing the anion

S

O 2−.

2

3

threshold

(n). Physical Science: the

magnitude or limit of something,

which, if exceeded, will cause

something else, e.g. release of

radiation, a chemical reaction, etc;

the minimum amount of energy

required to cause something.

Medicine: the maximum safety

level of a dose.

titrate

(v). To measure off a reagent

precisely drop by drop into a vessel

(container) containing another

reagent, so as to work out the

concentration of the reagent in the

vessel.

toxic, toxin

(adj., n.). Poisonous, poison.

transfer

(n). To move from one place to