definitions

Question 1

The d-block transition metals

Answer 1

metals with an incomplete d subshell in at least one of their ions.

Question 2

ligands

Answer 2

Ligands may be negative ions or molecules with non-bonding pairs of electrons that they donate to the central metal atom or ion, forming dative covalent bonds.

Question 3

coordination number

Answer 3

The total number of bonds from the ligands to the central transition metal is known as the coordination number.

Question 4

The equilibrium constant ( K )

Answer 4

characterises the equilibrium composition of the reaction mixture.

Question 5

ionic product

Answer 5

The dissociation constant for the ionisation of water

Question 6

buffer

Answer 6

A buffer solution is one in which the pH remains approximately constant when small amounts of acid, base or water are added.

Question 7

The standard enthalpy of formation, ∆H °f

Answer 7

the enthalpy change when one mole of a substance is formed from its elements in their standard states.

Question 8

standard state

Answer 8

The standard state of a substance is its most stable state at a pressure of 1 atmosphere and at a specified temperature, usually taken as 298 K.

Question 9

entropy

Answer 9

The entropy (S) of a system is a measure of the degree of disorder of
the system.

Question 10

The second law of thermodynamics

Answer 10

The second law of thermodynamics states that the total entropy of a reaction system and its surroundings always increases for a spontaneous process.

Question 11

The third law of thermodynamics

Answer 11

The third law of thermodynamics states that the entropy of a perfect crystal at 0 K is zero.

Question 12

The standard entropy of a substance

Answer 12

The standard entropy of a substance is the entropy value for the substance in its standard state.

Question 13

a feasible reaction

Answer 13

A feasible reaction is one that tends towards the products rather than the reactants

Question 14

The order of a reaction with respect to any one reactant

Answer 14

The order of a reaction with respect to any one reactant is the power to which the concentration of that reactant is raised in the rate equation.

Question 15

The overall order of a reaction

Answer 15

The overall order of a reaction is the sum of the powers to which the concentrations of the reactants are raised in the rate equation.

Question 16

hybridisation

Answer 16

Hybridisation is the process of mixing atomic orbitals within an atom to generate a set of new atomic orbitals called hybrid orbitals. These hybrid orbitals are degenerate.

Question 17

chromophore

Answer 17

A chromophore is a group of atoms within a molecule that is responsible for absorption of light in the visible region of the spectrum.

Question 18

a conjugated system

Answer 18

a system of adjacent unhybridised p orbitals that overlap side-on to form a molecular orbital across a number of carbon atoms.

Question 19

nucleophiles

Answer 19

negatively charged ions or neutral molecules that are electron rich

Question 20

electrophiles

Answer 20

positively charged ions or neutral molecules that are electron deficient

Question 21

SN1

Answer 21

SN1 is a nucleophilic substitution reaction with one species in the rate determining step and occurs in a minimum of two steps via a trigonal planar carbocation intermediate.

Question 22

SN2

Answer 22

SN2 is a nucleophilic substitution reaction with two species in the rate determining step and occurs in a single step via a single five-centred, trigonal bipyramidal transition state.

Question 23

DRUGS

Answer 23

Drugs are substances that alter the biochemical processes in the body.

Question 24

agonist

Answer 24

An agonist mimics the natural compound and binds to the receptor molecules to produce a response similar to the natural active compound.

Question 25

antagonist

Answer 25

An antagonist prevents the natural compound from binding to the receptor, and so blocks the natural response from occurring.

Question 26

enzyme inhibitors

Answer 26

enzyme inhibitors and act by binding to the active site of the enzyme and blocking the reaction normally catalysed there.