22.1 lattice enthalpy

Question 1

define lattice enthalpy

Answer 1

enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions

Question 2

is lattice enthalpy exothermic or endothermic?

Answer 2

exothermic

Question 3

define enthalpy change of atomisation

Answer 3

the enthalpy change that takes place for the formation of one mole of gaseous atoms from the element in its standard state under standard conditions

Question 4

is enthalpy change of atomisation exothermic or endothermic?

Answer 4

endothermic because bonds are broken to form gaseous atoms

Question 5

are ionistation energies exothermic or endothermic?

Answer 5

endothermic because energy is required to overcome the attraction between a negative electron and the positive nucleus

Question 6

what is electron affinity?

Answer 6

opposite of ionisation energy
measures the energy to gain electrons

Question 7

define first electron affinity

Answer 7

the enthalpy change that takes place when one electron is added to each atom in one mole of gaseous atoms to form one mole of gaseous 1- ions

Question 8

is first electron affinity exothermic or endothermic?

Answer 8

always exothermic as electron being added is attracted in towards the nucleus

Question 9

what is the born-haber cycle for?

Answer 9

lattice enthalpy can’t be measured so it must be calculated indirectly using known energy changes in an energy cycle

Question 10

are second electron affinities exothermic or endothermic?

Answer 10

endothermic as a second electron is being gained by a negative ion which repels electrons away
energy must be put in to force the negatively-charged electron onto the negative ion