Module 3 - The periodic table

Question 1

Definition : First ionisation energy

Answer 1

The energy required to remove 1 mole of electrons from a mole of gaseous atoms.

Question 2

How does nuclear charge affect ionisation energy?

Answer 2

More protons, more positively charged nucleus so stronger attraction for electrons

Question 3

How does atomic radius affect ionisation energy?

Answer 3

Attraction decreases with distance

Question 4

How does shielding affect ionisation energy?

Answer 4

Outer electrons feel less attraction to nuclear charge with increased shielding

Question 5

How does ionisation energy change as you go down a group?

Answer 5

Ionisation energy decreases
Extra electron shells
More shielding
Increased atomic radius

Question 6

How does ionisation energy change as you go across a period?

Answer 6

Ionisation energy increases
Number of protons increases, nuclear charge increases
No extra shielding, no extra shells
Some exceptions

Question 7

Why does ionisation energy drop between group 2 and 3?

Answer 7

Group 3 electrons start p orbital
p orbital has slightly higher energy than s
additional shielding from s to p

Question 8

Why does ionisation energy drop between group 5 and 6?

Answer 8

Group 5 orbital has 1 electron
Group 6 orbital has 2 electrons
Repulsion makes it easier to remove electron in group 6