lattice enthalpy and born haber cycles

Question 1

how can you work out the theoretical lattice enthalpy

Answer 1

by doing calculations on the purely ionic model of a lattice

Question 2

what does the purely ionic model of a lattice assume

Answer 2

that the ions are completely spherical and their charge is evenly distributed aroung them

Question 3

what can you get evidence for if you work out the lattice enthalpy experimentally

Answer 3

that most ionic compounds have some covalent character

Question 4

what does more polarisation mean in terms of covalent character

Answer 4

more polarisation means more covalent the bonding will be

Question 5

what is the definition of lattice enthalpy of formation

Answer 5

the enthalpy change when 1 mole of a solid ionic compound is formed from its gaseous ions under standard condition

Question 6

what is the definiton of lattice enthalpy of dissociation

Answer 6

the enthalpy change when 1 mole of a solid ionic compound is completely dissociated into its gaseous ions under standard conditions

Question 7

what is the extra step/s when calculating born haber cycles for group 2 elements

Answer 7

1) group 2 elements form 2+ ions so you have to include the second ionisation energy
2) usually theres 2 mols of the group 2 element so you have to double the atomisation enthalpy of the group 2 element
3) you need to double the first electron affinity of the group 2 element because you form 2 mols of the negative ion