Definitions

Question 1

The enthalpy of formation

Answer 1

The standard enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions, and all reactants and products in their standard states.

Question 2

The enthalpy of combustion

Answer 2

The standard enthalpy change when one mole of a substance is burned completely in oxygen.

Question 3

The enthalpy of atomization

Answer 3

The standard enthalpy change which accompanies the formation of one mole of gaseous atoms from the element in its standard state.

Question 4

The first ionisation energy

Answer 4

The enthalpy change when one mole of gaseous atoms is converted into a mole of gaseous ions each with a single positive charge

Question 5

The second ionisation energy

Answer 5

The enthalpy change when one mole of positively charged gaseous ions loses a mole of electrons.

Question 6

The first electron affinity

Answer 6

The enthalpy change when a mole of gaseous atoms is converted to a mole of gaseous ions, each with a negative charge.

Question 7

The second affinity

Answer 7

The enthalpy change when a mole of electrons is added to a mole of gaseous ions each with a single negative charge to form ions each with two negative charges.

Question 8

Lattice enthalpy of formation

Answer 8

The standard enthalpy change when one mole of a solid ionic compound is formed from its gaseous ions.

Question 9

Lattice enthalpy of dissociation

Answer 9

The standard enthalpy change when one mole of solid ionic compound dissociated into its gaseous ions.

Question 10

Enthalpy of hydration

Answer 10

The standard enthalpy change when water molecules surround one mole of gaseous ions

Question 11

Enthalpy of solution

Answer 11

The standard enthalpy change when one mole of solute dissolves completely in solution in sufficient solvent to form a solution in which molecules or ions are far enough apart to not interact with each other.

Question 12

Mean bond enthalpy

Answer 12

The enthalpy change when one mole of gaseous molecules each breaks a covalent bond to form two free radicals averaged over a range of compounds.

Question 13

Define Brønsted-Lowry acid

Answer 13

Proton Donor

Question 14

Define Lewis acid

Answer 14

Electron pair acceptor

Question 15

Define Acid derivative

Answer 15

Organic compound related to a carboxylic acid with the formula RCOZ where RCO represents an acyl group and Z = Cl, NHR, OR, or OCOR.

Question 16

Define activation energy

Answer 16

The minimum energy that a particle needs in order to react; the energy difference between the reactants and the transition state.

Question 17

Define aldehyde

Answer 17

An organic compound containing the general formula

RCHO

Question 18

What are the alkaline earth metals

Answer 18

The metals in Group 2 of the periodic table

Question 19

Define alkane

Answer 19

A hydrocarbon with C-C and C-H single bonds only with the general formula C_nH_2n+2

Question 20

Define allotropes

Answer 20

Pure elements which can exist in different physical forms in which their atoms are arranged differently. for example, diamond, graphite, and buckminsterfullerene are allotropes of carbon.

Question 21

Define anaerobic respiration

Answer 21

The process by which energy is released and new compounds are formed within living organisms in the absence of oxygen.

Question 22

Define Atom Economy

Answer 22

Describes the efficiency of the reaction by comparing the total number of atoms in the product with the total number in starting materials.

Question 23

Define Atomic orbital

Answer 23

A region of space around an atomic nucleus where there is a high probability of finding an electron.

Question 24

Define Avogadro constant

Answer 24

Number of particles in a mole

6.022x10²³

Question 25

Define Brønsted-Lowry base

Answer 25

Proton acceptor

Question 26

Define Lewis Base

Answer 26

Electron pair donor

Question 27

Define Base peak

Answer 27

The ion with the greatest abundance (tallest peak) in a mass spectrum

Question 28

Define Bond dissociation enthalpy

Answer 28

The enthalpy change to break a covalent bond in all the species in the gaseous state

Question 29

Define Buffer

Answer 29

A solution which resists changes to the pH when small amounts of acid/base are added to it. In the image, only solution B is the buffer.

Question 30

Define Calorimeter

Answer 30

An instrument for measuring the heat changes that accompany chemical reactions

Question 31

Define Carbocation

Answer 31

An organic ion in which one of the carbon atoms has a positive charge.

Question 32

Define Carbon-neutral

Answer 32

A process, or series of processes, in which as much carbon dioxide is absorbed from the air as is given out.

Question 33

Define Catalyst

Answer 33

A substance that alters the rate of a chemical reaction but is not used up in the reaction.

Question 34

Define Catalytic Cracking

Answer 34

The breaking, with the aid of a catalyst normally a zeolite of long-chain alkane molecules (obtained from crude oil) into shorter hydrocarbons. The reaction forms an ionic indeterminate. It also may produce some alkenes.

Question 35

Define Chelation

Answer 35

The process by which a multidentate ligand replaces a monodentate ligand in forming co-ordinate (dative) bonds to a transition metal ion.

Question 36

Define Chemical feedstock

Answer 36

The starting materials in an industrial chemical process.

Question 37

Define Chiral

Answer 37

This means 'handed'. A chiral molecule exists in two mirror-image forms that are not superimposable.

Question 38

Define Chiral Centre

Answer 38

An atom to which 4 different atoms or groups are bonded.

Question 39

Define Co-ordinate bond

Answer 39

A covalent bond in which both electrons in the bond come from one of the atoms. (Also known as a dative bond)

Question 40

Define Co-ordination number

Answer 40

The number of ligand molecules bonded to a metal ion.

Question 41

Define Covalent bonding

Answer 41

A chemical bond where two atoms share a pair of electrons between them.

Question 42

Define Delocalisation

Answer 42

The process by which electrons are spread over several atoms and help bond them.

Question 43

Define Dipole-dipole forces

Answer 43

An intermolecular force that results from the attraction between molecules with permanent dipoles.

Question 44

Define displacement reactions

Answer 44

A chemical reaction in which one atom replaces another atom in a compound.

Question 45

Define displayed formula

Answer 45

The formula of a compound drawn out so that each atom and each bond is shown

Question 46

Define Disproportionation

Answer 46

Redox Reaction in which the oxidation number of an element both increases and decreases.

Question 47

Define Dynamic Equilibrium

Answer 47

Constant concentration as forward reaction rate = bascward reaction rate.