energy

Question 1

describe how, and explain why, the lattice enthalpy of magnesium fluoride differs from that of calcium chloride

Answer 1

MgF2 more exothermic than CaCl2

ionic radius of Mg2+ smaller than Ca2+

stronger electrostatic attraction between cation and anion in Mg2+

Question 2

explain why the first ionisation of calcium is less positive than the second ionisation energy

Answer 2

second ionisation energy, electron closer to nucleus

second ionisation energy, electron is lost is from a particle that is already positive

Question 3

explain why the second ionisation energy of calcium is more endothermic than the first ionisation energy of calcium

Answer 3

Ca+ smaller than Ca

greater nuclear attraction

Question 4

suggest why the second electron affinity of oxygen is positive

Answer 4

takes heat energy to overcome bonds between negative ion and electron

Question 5

lattice enthalpies of calcium oxide and magnesium oxide are different

Answer 5

calcium has a larger ion size

LE MgO more exo

stronger attraction for o2