A2 chem definitions

Question 1

Co-ordination number of six

Answer 1

6 dative covalent bonds bonded to central metal atom/ion

Question 2

Electron affinity

Answer 2

E change when 1 e- is added to each atom in 1 mole of gaseous atoms

Question 3

Lattice Energy

Answer 3

Enthalpy change when 1 mole of solid ionic compound is formed from its gaseous ions under standard conditions

Question 4

Enthalpy change of solution

Answer 4

Energy change when 1 mole of solute is dissolved in an infinite amount of water to form a dilute solution

Question 5

Enthalpy change of atomisation

Answer 5

Energy change when 1 mole of gaseous atoms are formed from its element in standard state

Question 6

Enthalpy change of hydration

Answer 6

Energy change when 1 mole of gaseous ions is dissolved in an excess of water

Question 7

Bond Energy

Answer 7

The energy change when 1 mole of covalent bonds is broken in gaseous state

Question 8

Weak acid

Answer 8

An acid that is partially ionised

Question 9

Amphoteric

Answer 9

Can react with an acid or base

Question 10

Standard cell potential

Answer 10

Potential difference between 2 half cells under standard conditions of 1 atm, 298K, solutions being 1moldm^-3

Question 11

Standard electrode potential

Answer 11

Potential difference when a half cell is connected to standard hydrogen electrode under standard conditions of 1 atm, 298K, solutions being 1moldm^-3

Question 12

Rate of reaction

Answer 12

Change in amount of reactants per unit time

Question 13

Half-life of a reaction

Answer 13

The time is taken for the amount of reactant to halve

Question 14

Rate-determining step

Answer 14

Slowest step in the overall reaction

Question 15

Heterogenous

Answer 15

Different states

Question 16

Homogenous

Answer 16

Same States

Question 17

Heterogenous catalyst

Answer 17

Catalyst and the reactants are in the same phase

Question 18

Entropy

Answer 18

Measure of disorder of a system

Question 19

△G

Answer 19

Gibbs Free Energy change

Question 20

Order of reaction

Answer 20

The power to which the conc of a reactant is raised in the rate equation

Question 21

Reversible reaction

Answer 21

Reaction that can go in either direction

Question 22

Dynamic equilibrium

Answer 22

Rate of forward reaction = Rate of reverse reaction.

The concentration of all species remain unchanged

Question 23

Partition coefficient, Kpc / Kpartition

Answer 23

Ratio of concentration of a solute in the two immiscible solvents at equilibrium

Question 24

Transition element

Answer 24

Element that forms 1 or more stable ions with partially filled d-orbital

Question 25

Ligand

Answer 25

Species that uses LP to form dative covalent bonds to a central metal atom or ion

Question 26

Monodentate ligand

Answer 26

A species that donates a LP of e- to central metal atom or ion

Question 27

Bidentate ligand

Answer 27

An ion/molecule that donates 2 LPs of e- to central metal atom/ion

Question 28

Polydentate ligand

Answer 28

A species that donate more than 1 LPs of e- to central metal atom/ion

Question 29

Bidentate

Answer 29

An ion/molecule that donates 2 LPs of e- to central metal atom/ion

Question 30

Complex ion

Answer 30

An ion formed by a central metal atom/ion bonded to one or more ligands

Question 31

Degenerate

Answer 31

Orbitals have the same E

Question 32

Coordination number

Answer 32

The no. of dative covalent bonds formed by the central metal atom/ion

Question 33

Stability constant

Answer 33

Equilibrium constant for the formation of a complex ion in a solution

Question 34

Structural isomer

Answer 34

Same number and type of atoms but different structural formula

Question 35

Chiral centre

Answer 35

A carbon atom that has 4 different atoms or groups attached it

Question 36

Stereoisomerism

Answer 36

Compounds that have the same structural formula but different spacial arrangements

Question 37

Buffer solution / Buffer

Answer 37

A solution that resists the change of pH when a small amount of acid or alkali is added to it

Question 38

Electronegativity

Answer 38

The attraction by an atom of the e- in a bond

Question 39

Homolytic fission

Answer 39

Breaking of a bond to form two radicals

Question 40

Free radical

Answer 40

Species with an unpaired e-

Question 41

Protein

Answer 41

A polymer of amino acids joined by peptide bonds

Question 42

.

Answer 42

.

Question 43

Secondary structure

Answer 43

alpha-helix / beta-sheet

Question 44

Tertiary structure

Answer 44

folding of chains / 3D shape

Question 45

Polymerisation

Answer 45

Many monomers forming a polymer

Question 46

Condensation polymer

Answer 46

A polymer formed by the elimination of a small molecule

Question 47

Double helix

Answer 47

Two interlinked spirals

Question 48

Nano-sized

Answer 48

Measured in nm, btw (10^-9 to 10^-6)

Question 49

Nanosphere

Answer 49

Spheres with a diameter in the nanometre range

Question 50

Retention time

Answer 50

Time take for a compound to travel through the column

Question 51

Partition

Answer 51

Separation due to the different solubilities of the compounds in two phases

Question 52

Adsorption

Answer 52

Separation due to the different attractions between the compounds and the stationary phase, relative to their solubility in the solvent

Question 53

Rf value

Answer 53

Distance travelled by a compound from baseline over the distance travelled by the solvent front

Question 54

Zwitterion

Answer 54

Species having positive and negative ionic charges but no overall charge

Question 55

Hydrophobic

Answer 55

Cannot form bonds with water molecules

Question 56

Density of a substance

Answer 56

Mass per unit volume

Question 57

Transition metal complex

Answer 57

Ion or molecule formed by a central metal atom/ion and surrounded by 1 or more ligands

Question 58

Electronegativity, and how it relates to the concept of bond polarity

Answer 58

Electronegativity is the attraction by an atom of the electrons in a bond. Bond polarity is the difference in electronegativities at each end of the bond.