Definitions

Question 1

Isotope

Answer 1

Atoms of the same element with different numbers of neutrons and therefore different masses

Question 2

Relative isotopic mass

Answer 2

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

Question 3

Relative atomic mass

Answer 3

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

Question 4

Relative molecular mass

Answer 4

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

Question 5

Relative formula mass

Answer 5

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

Question 6

1st ionisation energy

Answer 6

The amount of energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions

• Nuclear charge
• shielding
• atomic radius
• nuclear attraction

Question 7

Oxidation

Answer 7

the loss of electrons ((formation of +ions))

an increase in the oxidation number (becomes more positive)

Question 8

Reduction

Answer 8

the gain of electrons ((formations of -ions))

a decrease in oxidation number (becomes less positive)

Question 9

Oxidising agent

Answer 9

a reagent that oxidises (takes electrons from) another species

Question 10

Reducing agent

Answer 10

a reagent that reduces (gives electrons to) another speicies

Question 11

Acid

Answer 11

an acid releases H+ ions in aqueous solution

an acid is a proton donor

Question 12

weak acid / strong acid

Answer 12

A strong acid is fully dissociated in solution and a weak acid partially partially dissociated

Question 13

Base

Answer 13

A proton acceptor

Question 14

Alkali

Answer 14

A soluble base that releases OH- ions in water (/solution)

Question 15

Salts

Answer 15

Salts are ionic compounds formed when the H+ ions in an acid are replaced by metal or ammonium ions

Question 16

ionic bonding

Answer 16

electrostatic attraction between positive and negative ions

Question 17

covalent bonding

Answer 17

The stong electrostatic attractions between a shared pair of electrons and the nuclei of bonded atoms

Question 18

lone pair

Answer 18

a pair of electrons in the outer shell not used in the bonding

Question 19

dative covalent bond

Answer 19

A shared pair of electrons in which the bonded pair is provided by one of the bonded atoms only

Question 20

Average bond enthalpy

Answer 20

The average enthalpy that takes place when breaking by homolytic fission one mole of a given type of bond in molecules of a gaseous species

Question 21

metallic bonding

Answer 21

The electrostatic attraction between positive metal ions and delocalised electrons

Question 22

malleable

Answer 22

can easily be bent into different shapes

Question 23

ductile

Answer 23

can be drawn into a wire

Question 24

gaint ionic lattice

Answer 24

there is a continuous lattice arrangement of + and - ions in three dimensions

Question 25

VSEPR

Answer 25

Valence shell electron pair repulsion - electron pairs repel each other - the repulsion between lone pair-lone pair>lone pair-bonded pair>bonded pair-bonded pair

Question 26

Van der Waals

Answer 26

London forces and permanent dipole-dipole forces

Question 27

London forces

Answer 27

The London dispersion force is the weakest intermolecular force. The London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force is sometimes called an induced dipole-induced dipole attraction.

Question 28

electronegativity

Answer 28

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

Question 29

Pauling value

Answer 29

defines the electronegativity of an element.

Question 30

permanent dipole

Answer 30

a small charge difference that does not change across a bond with partial charges on the bonding atoms (the result of the bonded atoms having different electronegativities)

Question 31

Polar covalent bond

Answer 31

A bond with a permanent dipole, with positive and negative partial charges on bonded atoms

Question 32

Polar molecule

Answer 32

a molecule with an overall dipole hving taken into account any dipoles across bonds and the shape of the molecule and its structure

Question 33

Hydrogen bond

Answer 33

a hydrogen bond is a strong dipole-dipole attraction between an electron difficient -NH, OH, HF on one molecule and a lone pair of electrons on a highly electronegative atom (N,O,F) on a different atom

Question 34

Group (on periodic table)

Answer 34

A vertical column in the periodic table. Elements in a group have similar chemical properties and their atoms have the same number of outer shell electrons.

Question 35

Period (on periodic table)

Answer 35

Horizontal rows in periodic table. Elements show trends in properties across the period

Question 36

Subshell

Answer 36

A subshell is a group of the same type of orbital

Question 37

Orbitals

Answer 37

Orbitals are regions of an atom containing up to two electrons with opposite spin