Definitions

Question 1

Define an isotope

Answer 1

atoms which have the same number of protons but different numbers of neutrons

Question 2

Define relative isotopic mass

Answer 2

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

Question 3

Define relative atomic mass

Answer 3

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

Question 4

Define relative molecular mass

Answer 4

The weighted mean mass of a molecule of that substance compared to 1/12th of the mass of an atom of carbon-12

Question 5

Define relative formula mass

Answer 5

The average mass of a formula unit of that substance compared to 1/12th of the mass of an atom of carbon-12

Question 6

Define a mole

Answer 6

The amount of substance that contains 6.02 x 10^23 particles

Question 7

Define molar mass

Answer 7

The mass (in grams) of 1 mole of a substance. The units of molar mass are g mol ^-1

Question 8

Define an orbital

Answer 8

A region of space that can hold up to 2 electrons, with opposite spins

Question 9

Define an ion

Answer 9

An atom or group of atoms that has lost or gained one or more electrons

Question 10

Define molecular formula

Answer 10

Shows the number of atoms of each element in one molecule of the substance

Question 11

Define empirical formula

Answer 11

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

Question 12

Define an acid

Answer 12

A compound that releases H+ ions in aqueous solution

Question 13

Define a base

Answer 13

A compound that neutralises an acid to form a salt

Question 14

Define an alkali

Answer 14

A type of base that dissolves in water to release hydroxide ions, OH-

Question 15

Define a salt

Answer 15

A compound formed when the H+ ion from an acid is replaced by a metal ion or an ammonium ion

Question 16

Define ionic bonding

Answer 16

The electrostatic attraction between positive and negative ions

Question 17

Define a giant ionic lattice

Answer 17

A regular array of alternating positive and negative ions

Question 18

Define a covalent bond

Answer 18

The attraction of a shared pair of electrons for the nuclei of the bonded atoms

Question 19

Define a dative covalent bond

Answer 19

One in which both of the electrons in the covalent bond are provided by the same atom

Question 20

What does the electron pair repulsion theory state

Answer 20

That the electron pairs in the outer shell of the central atom in a molecule repel each other and therefore arrange themselves to be as far away from each other as possible

Question 21

Define electronegativity

Answer 21

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

Question 22

Define induced dipole-dipole forces

Answer 22

Attractive forces between molecules that arise when random electron movements in one molecule cause an instantaneous dipole which in turn causes an induced dipole in the other molecule

Question 23

Define permanent dipole-dipole forces

Answer 23

Electrostatic attraction forces between polar molecules. The positive pole of one molecule is attracted to the negative pole of a neighbouring molecule

Question 24

Define a hydrogen bond

Answer 24

The intermolecular attraction between hydrogen covalently bonded to N, O, or F of one molecule and the LONE PAIR on N,O, or F in another molecule

Question 25

Define metallic bonding

Answer 25

The attraction between a lattice of positive ions and a sea of delocalised electrons

Question 26

Define oxidation

Answer 26

Loss of electrons or an increase in oxidation number

Question 27

Define reduction

Answer 27

Gain of electrons or a decrease in oxidation number

Question 28

Define oxidising agent

Answer 28

The substance that contains the element that is reduced

Question 29

Define reducing agent

Answer 29

The substance that contains the element that is oxidised

Question 30

Define functional group

Answer 30

An atom or group of atoms that gives a compound its characteristics chemical reactivity

Question 31

Define homologous series

Answer 31

A series of compounds that have the same functional group and the same general formula, and in which successive members of the series differ by an extra CH2 unit

Question 32

Define hydrocarbons

Answer 32

Compounds which contain only carbon and hydrogen

Question 33

Define saturated

Answer 33

Compounds which contain single bonds between carbon atoms

Question 34

Define isomer

Answer 34

Different compounds that have the same molecular formula

Question 35

Define structural isomers

Answer 35

Compounds that have the same molecular formula but different structural formula

Question 36

Define a radical

Answer 36

An atom or group of atoms which has an unpaired electron

Question 37

Define homolytic fission

Answer 37

The breaking of a covalent bond with one of the bonded electrons going to each atom, forming 2 radicals

Question 38

Define heterolytic fission

Answer 38

The breaking of a covalent bond forming a cation and an anion

Question 39

Define stereoisomers

Answer 39

Compounds with the same structural formula but with a different arrangement in space

Question 40

Define an electrophile

Answer 40

An electron pair acceptor

Question 41

What is meant by the term standard solution

Answer 41

A solution of known concentration