Chemical Bonding

Question 1

Molecular orbital

Answer 1

A combined orbital formed from the overlap of two orbitals in a covalent bond

Question 2

Description of sigma bonds

Answer 2

Orbitals overlap linearly/end-on

Question 3

Lone pair-bond pair repulsion VS bond-pair bond-pair repulsion

Answer 3

Lone pair-bond pair repulsion is greater than bond pair-bond pair repulsion, so bonding pairs of electrons are pushed closer together and angle becomes smaller

Question 4

Angle between bonds in sp² hybridised carbon

Question 5

Acid

Answer 5

A proton donor

Question 6

Acid-base indicator

Answer 6

A substance that changes colour over a narrow range of pH values

Question 7

Bio-fuels

Answer 7

Renewable fuels sourced from plant/animal material

Question 8

Boltzmann distribution

Answer 8

A graph showing the distribution of energies of the particles in a sample at a given temperature

Question 9

Born-Haber cycle

Answer 9

Type of enthalpy cycle used to calculate other enthalpies, usually lattice energy

Question 10

Brønsted-Lowry theory of acids

Answer 10

Acids are proton donors and bases are proton acceptors

Question 11

Carbocation

Answer 11

An alkyl group carrying a single positive charge on one of its carbon atoms

Question 12

Amphoteric

Answer 12

Can behave as both an acid and a base

Question 13

Adsorption (in catalysis)

Answer 13

The first step in heterogeneous catalysis; molecules of reactants form bonds with atoms on the surface of the catalyst

Question 14

Addition polymerisation

Answer 14

The reaction in which monomers containing carbon-carbon double bonds react together to form long-chain molecules called polymers

Question 15

Active site of an enzyme

Answer 15

The pocket on an enzyme surface where the substrate binds and undergoes catalytic reaction

Question 16

Addition reaction

Answer 16

An organic reaction in which two reactant molecules combine to give a single product molecule

Question 17

Acid-dissociation constant (Ka)

Answer 17

The equilibrium constant for a weak acid

Question 18

Activation energy

Answer 18

The minimum energy that colliding particles must possess foe a successful collision that results in a reaction

Question 19

Alkali

Answer 19

A soluble base

Question 20

Alkaline earth metals

Answer 20

The elements in Group 2 of the Periodic Table

Question 21

Alkanes

Answer 21

Saturated hydrocarbons with the general formula CnH2n+2

Question 22

Alkenes

Answer 22

Unsaturated hydrocarbons that have the general formulae CnH2n and have a carbon-carbon double bond

Question 23

Chiral center

Answer 23

A carbon atom with 4 different groups attached creating the possibility of optical isomers

Question 24

Denaturation

Answer 24

The process by which the three dimensional structure of a protein or other biological macromolecule is changed often irreversibly; can be caused by high temperatures, extremes of pH and organic solvents

Question 25

Desorption

Answer 25

The final stage in heterogeneous catalysis in which the bonds holding the molecules of products to the surface of the catalyst are broken and the product molecules diffuse away from the surface of the catalyst

Question 26

Enthalpy of atomisation

Answer 26

The enthalpy change when one mole of gaseous atoms are formed from its constituent element in its standard state under standard conditions