Definitions

Question 1

activation energy

Answer 1

minimum amount of energy needed to start a reaction by the breaking of bonds

Question 2

alkali

Answer 2

a soluble base which releases hydroxide ions

Question 3

Atomic orbital

Answer 3

a region of space around the nucleus that can hold up to 2 electrons with opposite spins

Question 4

bond enthalpy

Answer 4

the energy needed to break one mole of a specified bond in the gas state

Question 5

buffer solution

Answer 5

a system which minimises PH changed when small amounts of acid or base are added

Question 6

catalyst

Answer 6

a substance which increases the rate of reaction by providing an alternative route of lower activation energy

Question 7

covalent bond

Answer 7

electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Question 8

d-block element

Answer 8

an atom that has its highest energy electron in a d subshell

Question 9

dative covalent bond

Answer 9

a shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms

Question 10

disproportionation

Answer 10

a redox reaction where the same element is oxidised and reduced

Question 11

dynamic equilibrium

Answer 11

a continous reaction in a closed system where the rate of the forward reaction is the same as the rate of the reverse reaction and the concentrations remain constant

Question 12

electronegativity

Answer 12

the ability of an atom to attract the pair of electrons in a covalent bond

Question 13

first ionisation energy

Answer 13

the energy needed to remove on mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions

Question 14

homogenous catalyst

Answer 14

a catalyst which is in the same physical state as the reactants

Question 15

heterogenaous

Answer 15

a catalyst which is in a different physical state to the reactants

Question 16

hydrogen bond

Answer 16

a strong dipole-dipole attraction between an electron deficient hydrogen atom of -NH, -OH, or HF and the lone pair of the N, O, F on a neighbouring molecule

Question 17

ioinic bond

Answer 17

electrostatic attraction between oppositely charged ions

Question 18

metallic bond

Answer 18

electrostatic attraction between metal cations and delocalised electrons

Question 19

rate of reaction

Answer 19

the change in the concentration of a reactant or product in a given time

Question 20

reducing agent

Answer 20

a species that donates electrons

Question 21

relative atomic mass

Answer 21

weighted mean/average mass of an atom of an element compared to 1/12th of the mass of an atom of carbon-12

Question 22

relative isotopic mass

Answer 22

mass of an isotope compared to 1/12th of the mass of an atom of carbon-12

Question 23

oxidising agent

Answer 23

a species which accpets electrons

Question 24

simple molecular lattice

Answer 24

a three dimensional structure of molecules held together by imf

Question 25

standard solution

Answer 25

a solution of known concentration

Question 26

standard enthalpy change iof combustion

Answer 26

the enthalpy change when one mole of a substance is reacted completely with oxygen under standard conditions

Question 27

standard enthalpy change of formation

Answer 27

the enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions

Question 28

standard enthalpy change of neutralisation

Answer 28

the enthalpy change when an acid and base react to form a mole of water under standard conditions