Glossary - A

Question 1

Absolute Temperature

Answer 1

A temperature based on the thermodynamic (ideal gas) scale, measured from absolute zero; absolute temperature = (temperature in Celsius + 273) K.

Question 2

Absolute Zero

Answer 2

The temperature to which substances cannot be cooled. Corresponds to complete absence of heat; the temperature at which all ionic, molecular and atomic vibrations cease and at which the pressure and volume of an ideal gas are zero.

Question 3

Absorbance

Answer 3

Logarithm of the fractional transmission of light (often at a specified wavelength) through a sample.

Question 4

Accurate Measurement

Answer 4

A measurement obtained using accurately calibrated instruments correctly and where no systematic errors arise: close to true value of the measurement.

Question 5

Acid

Answer 5

A proton donor and/or electron pair acceptor

Question 6

Acid-Base Indicator

Answer 6

A weak acid whose dissociated and undissociated forms in aqueous solution are different colors. The proportion of the two colored forms vary with pH; used to show changes in the pH of aqueous solutions.

Question 7

Acid-Base Reactions

Answer 7

Transfer of protons/ hydrogen ions from an acid to a base.

Question 8

Acidic Oxide

Answer 8

A covalent oxide, usually an oxide of a non-metal, that reacts and dissolves in water to form a solution of an acid - if insoluble in water, oxide reacts with alkalis to give salts.

Question 9

Addition Polymerization

Answer 9

A type of polymerization that occurs when alkene-based monomers undergo repeated addition reactions to form a single molecule.

Question 10

Addition Reaction

Answer 10

A reaction in which two (or more) molecules combine to form a single molecule.

Question 11

Alcohols

Answer 11

A homologous series of organic compounds containing functional group -OH and general formula CnH2n+1OH.

Question 12

Aldehydes

Answer 12

A homologous series of compounds with the general formula RCHO, where the -CHO group (the aldehyde group) consists of a carbonyl group attached to a hydrogen atom; R is usually an alkyl or aryl group.

Question 13

Aliphatic

Answer 13

An organic compound that has carbon atoms arranged in a chain or branched form rather than atomic ring.

Question 14

Alkali

Answer 14

A strong base which is soluble in water; alkalis are group 1 metal hydroxides and barium hydroxide.

Question 15

Alkali Metals

Answer 15

The group of very reactive metals in group 1 of the periodic table;they react
with water to release hydrogen gas and form strongly alkaline solutions.

Question 16

Alkanes

Answer 16

Saturated hydrocarbons which have the general formula CnH2n+2 (if acyclic).

Question 17

Alkyl Group

Answer 17

a group, with the general formula CnH2n+1, obtained by removing a hydrogen atom from an alkane, and usually represented by R.

Question 18

Alkynes

Answer 18

Unsaturated hydrocarbons with a carbon–carbon triple bond and with the general formula CnH2n–2 (if acyclic).

Question 19

Allotrope

Answer 19

Different structures of an element.

Question 20

Allotropy

Answer 20

The ability of an element to exist in

different structural forms or allotropes.

Question 21

Alloy

Answer 21

Mixture with metallic properties made up of two or more metals, or which contains metals and carbon.

Question 22

Amide Link

Answer 22

A chemical bond formed between
two molecules when the carboxyl group of one molecule reacts with the amine group of the other molecule, thereby releasing a molecule of water.

Question 23

Amide

Answer 23

A homologous series of organic

compounds with the general formula RCONH2.

Question 24

Amines

Answer 24

Organic compounds derived by replacing one or more of the hydrogen atoms in ammonia by alkyl groups.

Question 25

Amount

Answer 25

A physical quantity indicating the number of moles of a substance present in a sample.

Question 26

Ampere

Answer 26

The SI unit of electrical current:a current of one ampere (amp) is a flow of one coulomb of charge per second (1A = 1Cs–1).

Question 27

Analyse

Answer 27

Interpret data to reach conclusions.

Question 28

Anhydrous Salt

Answer 28

A salt that does not have its

water of crystallization.

Question 29

Anion

Answer 29

A negatively charged ion which migrates
to the anode (positive electrode) during
electrolysis.

Question 30

Annotate

Answer 30

Add brief notes to a diagram or graph.

Question 31

Anode

Answer 31

Where oxidation (the loss of electrons) occurs during an electrochemical process; in an electrolytic cell the anode is the positive electrode.

Question 32

Anomalous Data

Answer 32

Data with unexpected values that does not match the relationship predicted by the hypothesis.

Question 33

Aromatic

Answer 33

An organic compound that contains

a benzene ring.

Question 34

Atomic Number

Answer 34

The number of protons in the nucleus of an atom; in atoms the atomic number is also equal to the number of extra- nuclear electrons.

Question 35

Atomic Radius

Answer 35

Half the distance of the closest approach of the nuclei of atoms in the crystal or molecule of a chemical element.

Question 36

Average Bond Enthalpy

Answer 36

Enthalpy change per mole when one mole of the same type of covalent bond is broken in the gas phase for many similar molecules.

Question 37

Average Rate of Reaction

Answer 37

Calculated by dividing the total change in reactant or product concentration by the time for the reaction to end.

Question 38

Avogadro’s Law

Answer 38

At a specified temperature and pressure, equal volumes of (ideal) gases contain equal numbers of moles of particles; there is a directly proportional relationship between the volume of gas, V, and the amount of particles (at constant pressure), n: V

Question 39

Avogadro’s Constant

Answer 39

The number of atoms in exactly 12 grams of carbon-12; it has units of per mol (mol–1).