recipe cards

Question 1

explain ionic bonding (2)

Answer 1

. an electrostatic force of attraction
. between oppositely charged ions

Question 2

explain covalent bonding (2)

Answer 2

. an electrostatic force of attraction
. between a shared pair of electrons and the two nuclei

Question 3

explain metallic bonding (2)

Answer 3

. an electrostatic force of attraction
. between positive metal ions and a sea of delocalised electrons

Question 4

explain london forces (6)

Answer 4

. occur between all molecular substances (❌ ionic)
. electrons move constantly which makes the electron density fluctuate
. temporary dipole forms and causes induced dipoles in neighbouring molecules
. more electrons, higher chance dipoles form
- lf’s stronger, more energy to overcome
. long straight chain, higher lf’s, larger s.a

Question 5

explain dipole-dipole forces (6)

Answer 5

. occur between polar molecules
- asymmetrical, diff in electronegativity
. stronger than lf’s, higher bp
. between neighbouring molecules
. occurs with lf’s
. they are permanent

Question 6

explain hydrogen bonding (4)

Answer 6

. in compounds that have hydrogen attached to either F, O, N
- large diff in electronegativity
. occurs with lf’s
. stronger than lf and dipole-dipole

Question 7

explain solubility (2)

Answer 7

. a complicated balance of energy required to break bonds in the solute and solvent
. against energy give out making new bonds between the solute and solvent

Question 8

explain ionic substances dissolving in water (3)

Answer 8

. negative ions are attracted to δ+ hydrogens
. positive ions are attracted to the δ- oxygen
. higher the charge density, greater hydration enthalpy

Question 9

explain why smaller alcohols are soluble in water (2)

Answer 9

. they can form hydrogen bonds with water
. longer the hydrocarbon chain, less soluble the alcohol

Question 10

explain why propanone is a useful solvent (3)

Answer 10

. has both polar and non polar characteristics
. forms London forces with some non polar substances
. C=O bond can also hydrogen bond with water

Question 11

explain why F₂ has a low melting point but MgF₂ has a high melting point (4)

Answer 11

. F₂ is a compound with weak London forces between its molecules
. these forces are easy to overcome so they need little energy
. MgF₂ has strong ionic bonds between the Mg2+ and F- ions
. the electrostatic forces are much stronger than the ones in F₂ and require a larger amount of energy to overcome

Question 12

give the meaning of the term periodicity (3)

illustrate your answer by referring to the atomic radii of the period 2 and 3 elements

Answer 12

• periodicity is a pattern of repeating chemical or physical properties while increasing the atomic number
• atomic radii decreases as you go across a period
• this pattern is repeated in period 3

Question 13

explain why are alkanes generally unreactive (3)

Answer 13

• the C-H and C-C bonds are strong
• C andH form non-polar bonds
• only experience LF’s

Question 14

Tetrachloromethane can be manufactured using the by-products of chlorination reactions.
C₂Cl₆ + Cl ₂ → 2CCl ₄

Compare the atom economy of this process with that of the reaction which produces
tetrachloromethane from trichloromethane and chlorine. A calculation is not required.

Answer 14

• the atom economy is 100% as there’s only one product

OR
- no by product
- no waste product formed