Ionisation Energies

Question 1

IE’s increase across a period due to…

Answer 1

> NUCLEAR CHARGE

The greater the nuclear charge the greater the attractive force on the outer electron

Question 2

IE’s decrease down a group due to…

Answer 2

> SHIELDING
Repulsion from inner electrons tends to reduce the effect of the nucleus on the electron being ionised
ATOMIC RADIUS
The bigger the distance from the nucleus the smaller the attractive force on the outer electron

Question 3

Describe blip between Be and B

Answer 3

> extra electron in B is in the 2p orbital and so has some shielding from 2s electrons lowering IE

Question 4

Describe blip between N and O

Answer 4

> extra electron in o joins and already singly occupied p orbital and so has some repulsion between the two electrons lowering IE

Question 5

Write the 3rd IE of Sodium

Answer 5

Na^2+ (g) –> Na^3+ (g) + e^-

Question 6

Why do successive IE’s always increase

Answer 6

> As each electron is removed there is less electron-electron repulsion and each shell will be drawn in slightly closer to the nucleus
As distance of each electron from nucleus decreases nuclear attraction increases