Definitions S

Question 1

Sigma bond

Answer 1

A bond formed by the overlap of one orbital from each bonding atom, consisting of two electrons and with the electron density centred around the line directly between the nuclei of the two atoms

Question 2

Salt

Answer 2

The product of a reaction in which the H+ ions from the acid are replaced by metal or ammonium ions

Question 3

Saturated

Answer 3

Containing single bonds only

Question 4

Saturated hydrocarbon

Answer 4

A hydrocarbon with single bonds only

Question 5

Second ionisation energy

Answer 5

The energy required to remove one electron from each ion in one mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions

Question 6

Simple molecular lattice

Answer 6

Simple molecular structures have covalent bonds joining the atoms together they have low melting and boiling points as there are only weak intermolecular forces acting between the molecules.

Question 7

Skeletal formula

Answer 7

A simplified organic formula, with a hydrogen atom removed from alkyl chains chains, leaving just carbon skeleton and associated functional groups

Question 8

Specific heat capacity

Answer 8

The energy required to raise the temperature of 1 g of a substance by 1K

Question 9

Standard enthalpy change of combustion

Answer 9

The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, with all reactants and products in their standard states.

Question 10

Standard enthalpy change of formation

Answer 10

The enthalpy change that takes place when one mole of product is formed from its elements under standard conditions, with all reactants and products in their standard states

Question 11

Standard enthalpy change of neutralisation

Answer 11

The enthalpy change to form one mole H2O (l) from an acid reacting with a base under standard conditions, with all reactants and products in their standard states

Question 12

Standard enthalpy change of reaction

Answer 12

The enthalpy change of a standard reaction, a reaction with standard conditions

Question 13

Standard solution

Answer 13

A solution of known concentration

Question 14

Standard state

Answer 14

The physical state of a substance under standard conditions.

Question 15

Stereoisomers

Answer 15

Compounds with the same structural formula but with different arrangement of atoms in space

Question 16

Stoichiometry

Answer 16

The ratio of the amounts, in moles, each substance in a chemical reaction

Question 17

Strong acid

Answer 17

An acid that dissociates completely in the solution

Question 18

Structural formula

Answer 18

The formula showing the minimal detail for the arrangement of atoms in a molecule

Question 19

Structural isomers

Answer 19

Compounds with the same molecular formula but different structural formulae

Question 20

Sub-shell

Answer 20

Group of orbitals of the same type within the shell

Question 21

Substitution reaction

Answer 21

A reaction in which one atom or group of atoms is replaced by another atom or group of atoms