Lattice Energy

Question 1

definition of lattice energy

Answer 1

enthalpy change when one mole of ionic compound is formed from its gaseous ions under standard conditions

Question 2

enthalpy change of lattice energy

Answer 2

exothermic

Question 3

Na+(g) + Cl-(g) → NaCl (s) is an example of

Answer 3

lattice energy

Question 4

what does large exothermic value for lattice energy mean

Answer 4

more stable and strong ionic bonding

Question 5

suggest reason for difference in LE between calcium oxide and iron (II) oxide

Answer 5

iron has smaller ionic radius = high charge density

Question 6

key words for mentioning lattice energy difference (4)

Answer 6

ionic radius
charge density
electrostatic attraction between cation and anion
charge on ion

Question 7

definition of enthalpy change of atomisation

Answer 7

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

Question 8

enthalpy change of atomisation

Answer 8

endothermic

Question 9

why is enthalpy change of atomisation endothermic

Answer 9

energy must be supplied to break the bonds holding atom together

Question 10

Li(s) –> Li(g) is an example of

Answer 10

enthalpy change of atomisation

Question 11

definition of enthalpy change of hydration

Answer 11

the enthalpy change when one mole of gaseous ions dissolves in sufficient water to form an infinitely dilute solution

Question 12

enthalpy change of hydration

Answer 12

exothermic

Question 13

trends in enthalpy change of hydration

Answer 13

more exothermic with smaller ions

high charge density makes stronger bonds with water molecule

Question 14

definition of enthalpy change of solution

Answer 14

the energy absorbed or released when one mole of an ionic solid dissolves in sufficient amount of water to form an infinitely dilute solution

Question 15

enthalpy change of solution (aq)

Answer 15

exo/endo (little changes)

large values are insoluble

Question 16

definition of first ionisation energy

Answer 16

enthalpy change when one electron is removed from each atom in one mole of gaseous atoms under standard conditions

Question 17

enthalpy change of first ionisation energy

Answer 17

endothermic

Question 18

why is first ionisation eneergy endothermic

Answer 18

energy needed to overcome the force of attraction between outer electrons and nucleus

Question 19

why is first ionisation energy of calcium less positive than its second ionisation energy

Answer 19

electron lost is closer to the nucleus
electron lost from positive ion
outer electron more firmly attracted to the nucleus

Question 20

definition of first electron affinity

Answer 20

enthalpy change when one mole of electrons is added to one mole of gaseous atoms to form one mole of gaseous 1- ions under standard conditions

Question 21

enthalpy change of first electron affinity

Answer 21

exothermic

Question 22

why is first electron affinity exothermic

Answer 22

electron experience attraction to the nucleus, energy absorbed to overcome repulsion

Question 23

Cl(g) + e → Cl- (g) is an example of

Answer 23

first electron affinity

Question 24

definition of second electron affinity

Answer 24

enthalpy change when one mole of electrons is added to one mole of gaseous 1- ions to form one mole of gaseous 2- ions under standard conditions

Question 25

enthalpy change of second electron affinity

Answer 25

endothermic

Question 26

why is second electron affinity endothermic

Answer 26

ion and electron both negative + energy required to overcome repulsion

Question 27

O- (g) + e → O2-(g) is an example of

Answer 27

second electron affinity

Question 28

factors affecting electron affinity

Answer 28

nuclear charge distance shielding from electrons (shielding + distance offsets)

Question 29

what does low electron affinity mean

Answer 29

more wanting to give up its electron and has weak pull on valence of electrons

Question 30

trend of electron affinity with halogens

Answer 30

becomes less negative (further away from outer shell = less energy released)

Question 31

why is fluorine a less exothermic value than chlorine

Answer 31

very small and pushing in electron require some energy - crowded speace = less energy released

Question 32

look at born haber cycle ok

Answer 32

ok

Question 33

definition of enthalpy change of formation

Answer 33

enthalpy change when ionic compound formed from its elements under standard conditions

Question 34

enthalpy change of what (2) in born haber cycle

Answer 34

formation | lattice

Question 35

factors affecting lattice energy

Answer 35

ion size | charge on ions

Question 36

definition of polarising power

Answer 36

ability of cation to attract e and distort an anion

Question 37

describe ion polarisaion

Answer 37

small cation has high charge density and able to distort large anion

Question 38

describe trend of thermal stability of group 2 carbonates/nitrates

Answer 38

increasing stability increasing ionic size = low charge density polarising ability on nitrate decreases

Question 39

trend of solubility of sulphates

Answer 39

less soluble down the group lattice energy and hydration energy both decrease hydration decreases more enthalpy of solution more endothermic

Question 40

equation for E.sol

Answer 40

E.latt - E.hyd

Question 41

trend of solubility of hydroxides

Answer 41

more soluble lattice and hydration energy both decrease lattice energy decreases more enthalpy change of solution less endothermic