Definitions

Question 1

Homogenous mixture

Answer 1

A mixture of uniform composition and in which all components are in the same phase

Question 2

Heterogenous mixture

Answer 2

A mixture of non-uniform composition and of which the components can be easily identified

Question 3

Electrical conductor

Answer 3

A material that allows the flow of charge

Question 4

Electrical insulator

Answer 4

A material that prevents the flow of charge

Question 5

Thermal conductor

Answer 5

A material that allows heat to pass through easily

Question 6

Thermal insulator

Answer 6

A material that does not allow heat to pass through it

Question 7

Diffusion

Answer 7

The movement of atoms or molecules from an area of higher concentration to an area of lower concentration

Question 8

Boiling point

Answer 8

The temperature of a liquid at which its vapour pressure equals the external (atmospheric) pressure

Question 9

Melting point

Answer 9

The temperature at which a solid, given sufficient heat, becomes a liquid

Question 10

Isotope

Answer 10

Atoms of the same element having the same number of protons but a different number of neutrons

Question 11

Valence electrons

Answer 11

The electrons found in the outermost orbital of an atom

Question 12

Pauli’s Exclusion Principle

Answer 12

Maximum of two electrons per orbital provided that they spin in opposite directions

Question 13

Atomic orbitals

Answer 13

The most probable regions in space where electrons that have the specific energy corresponding to the orbital are found

Question 14

Hund’s Rule

Answer 14

No pairing in p-orbitals before there is at least one electron in each of them

Question 15

Heisenberg’s Uncertainty Principle

Answer 15

It is impossible to determine both the velocity and the position of an electron at the same time

Question 16

Atomic radius

Answer 16

The mean distance from the nucleus to the border of the outer orbital

Question 17

First Ionisation energy

Answer 17

The energy needed per mole to remove the first electron from an atom in the gaseous phase

Question 18

Electron-affinity

Answer 18

The energy released when an electron is attached to an atom or molecule to form a negative ion

Question 19

Electronegativity

Answer 19

A measure of the tendency of an atom in a molecule to attract bonding electrons

Question 20

Mole

Answer 20

Amount of substance having the same number of particles there are atoms in 12g of carbon-12

Question 21

Relative atomic mass

Answer 21

Mass of a particle on a scale where an atom of carbon-12 has a mass of 12

Question 22

Molar mass

Answer 22

The mass of one mole of a substance measured in g.mol⁻¹

Question 23

Empirical formula

Answer 23

The simplest whole-number ratio of atoms in a compound

Question 24

Water of crystallisation

Answer 24

Water that is stoichiometrically bound into a crystal

Question 25

Concentration

Answer 25

The number of moles of solute per cubic decimeter of solution

Question 26

Avagadro’s Law

Answer 26

One mole of any gas occupies the same volume at the same temperature and pressure