IONISATION ENERGIES

Question 1

What is the first ionisation energy

Answer 1

Its the energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of ions with a single positive charge.

ENDOTHERMIC - Breaking bonds

Question 2

General equation for IE1

Answer 2

X (g) –> X + (g) + e-

Question 3

General equation for IE2

Answer 3

X+(g) –> X 2+ (g) = e-

Question 4

Why is IE2 larger than IE1

Answer 4

because the e- is being removed from an ion with a + charge.
+ ion has smaller radius than an atom so outer electron is closer to the nucleus, stronger attracted to it and harder to remove

Question 5

Ionisation energy trends - GROUPS

Answer 5

IE DECREASES as you go down GROUPS (vertical)
Outer e- gets further away from the nucleus so the core e- sheild.

Question 6

Ionisation energy trends - PERIODS

Answer 6

IE INCREASES as you go across periods (horizontal)
More protons, greater + charge so the e- becomes tighter in

Question 7

Explanation for higher ionisation energies

Answer 7

• more protons, stronger attraction between nucleus and valence e-, more energy needed to remove outer e-
• higher energy levels mean core e- shields valence e- from full nuclear charge, making e- easier to remove from the atom, turning atom into a + charged ion because it has more protons than electrons (cation)

Question 8

Explanation for lower ionisation energies

Answer 8

• less protons, weaker attraction between nucleus and valence e-, less energy needed to remove the outer e-.