Aqa As Chemistry Unit 1 Foundation Chemistry Definitions

Front 1

Atomic number

Back 1

the number of protons in the nucleus of an atom

Front 2

Mass number

Back 2

the total number of protons and neutrons in the nucleus of an atom

Front 3

Isotopes

Back 3

atoms with the same atomic number but different mass numbers or atoms with the same number of protons but different numbers of neutrons

Front 4

Relative isotopic mass

Back 4

the ratio of the mass of one atom of that isotope to 1/12th of the mass of one atom of carbon-12

Front 5

Relative atomic mass

Back 5

the ratio of the average mass of an atom to 1/12th of the mass of one atom of carbon-12

Front 6

Relative molecular mass

Back 6

the ratio of the average mass of a molecule (or formula unit) to 1/12th of the mass of carbon-12

Front 7

First ionisation energy

Back 7

the heat energy required to remove one electron from each of a mole of free gaseous atoms of that element

Front 8

Second ionisation energy

Back 8

the heat energy required to remove one electron from each of a mole of free gaseous unipositive ions of that element

Front 9

Avogadro's number

Back 9

the number of elementary particles that there are in 12.000 grams of carbon-12

Front 10

Mole

Back 10

the amount of a substance containing the same number of elementary particles as there are in 12.000 grams of carbon-12

Front 11

Molar mass

Back 11

the mass of a substance containing the same number of elementary particles as there are in 12.000 grams of carbon-12

Front 12

Empirical formula

Back 12

the simplest whole number ratio in which the atoms of each element in a compound are found

Front 13

Molecular formula

Back 13

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

Front 14

Ionic bond

Back 14

an attraction between oppositely charged ions

Front 15

Covalent bond

Back 15

a pair of electrons shared between two atoms

Front 16

Dative covalent bond

Back 16

a pair of electrons shared between two atoms, one of which provides both of the electrons

Front 17

Metallic bond

Back 17

an attraction between a cation and a sea of delocalised electrons

Front 18

Electronegativity

Back 18

the ability of an atom to attract electrons towards itself in a covalent bond.

Front 19

Polar bond

Back 19

the existence of partial positive and negative charges on each end of the bond as a result of the unequal sharing of electrons

Front 20

s-block element

Back 20

an element with s-electrons only in its outer shell

Front 21

p-block element

Back 21

an element with p-electrons in its outer shell

Front 22

d-block element

Back 22

an element with s and d-electrons but no p-electrons in its outer shell

Front 23

Homologous Series

Back 23

series of compounds with the same functional group in which the molecular formula varies by –CH2- from one member to the next

Front 24

Isomerism

Back 24

a number of different structures having the same molecular formula

Front 25

Structural Isomerism

Back 25

the same molecular formula, but a different arrangement of covalent bonds

Front 26

Chain Isomerism

Back 26

the same molecular formula, but a different arrangement of carbon atoms in the chain

Front 27

Positional Isomerism

Back 27

the same molecular formula, but the functional group in a different position

Front 28

Functional Isomerism

Back 28

the same molecular formula, but a different functional group

Front 29

Functional group

Back 29

an atom or group of atoms which confer specific physical and chemical properties to the molecule