DEFINITIONS

Question 1

relative isotopic mass

Answer 1

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

Question 2

relative atomic mass

Answer 2

weighted mean mass of an element compared with 1/12th of the mass of an atom of carbon 12

Question 3

relative molecular mass

Answer 3

weighted mean mass of a molecule compared with 1/12th of the mass of an atom of carbon 12

Question 4

relative formula mass

Answer 4

weighted mean mass of a formula unit compared with 1/12th of the mass of an atom of carbon 12

Question 5

stoichiometry

Answer 5

the ratio of amount of substance between chemical species in a balanced equation

Question 6

molecular formula

Answer 6

actual number of atoms of each element in a molecule

Question 7

empirical formula

Answer 7

the simplest whole number ratio of atoms of each element present in a compound

Question 8

molar volume

Answer 8

volume per mole of a gas

Question 9

amphoteric

Answer 9

both acid and a base

Question 10

waters of crystallisation

Answer 10

refers to water molecules that form an essential part of the crystalline structure of a compound

Question 11

oxidation number

Answer 11

measure of the number of electrons that an atom uses to bond with an atom of another element

Question 12

disproportionation reaction

Answer 12

same element is stimultaneously oxidised and reduced

Question 13

electronegativity

Answer 13

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

Question 14

non-polar bonds

Answer 14

electronegativity of both atoms in a covalent bond are idetntical, creatin symmetrical distribution of electron denisity

Question 15

homologous series

Answer 15

a series of organic compounds having the same functional group but with different number of carbon atoms

Question 16

structural isomerism

Answer 16

compounds with the same molecular formula have their atoms arranged in different orders

Question 17

positive isomers

Answer 17

same chain shape but the functional group is on a different carbon

Question 18

sigma bond

Answer 18

direct overlap of orbitals
a covalent bond

Question 19

stereo isomerism

Answer 19

same structural formula, different arrangement in space

Question 20

heterolytic fission

Answer 20

when a bond breaks and both electrons go to the same atom

Question 21

free radicals

Answer 21

any species with a free, unpaired electron

Question 22

pi bond

Answer 22

indirect overlap of orbitals

Question 23

what is a salt

Answer 23

when the H+ in an acid is replaced by a metal ion

Question 24

alkali

Answer 24

a soluble base which releases OH-

Question 25

atomic orbitals

Answer 25

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

Question 26

conjugate acid base pair

Answer 26

a pair of species in an acid base equilibrium that transform into each other by gain or loss of a proton

Question 27

first ionisation energy

Answer 27

the energy needed to remove one mole of electrons from one mole of gaseous atoms