Ionisation Energy

Question 1

Define IONISATION ENERGY

Answer 1

The energy required to remove one mole of the most loosely held electrons from one mole of gaseous atoms to produce one mole of gaseous ions each with a charge of +1

Question 2

Write the reaction of the first and second ionisation energy of sodium

Answer 2

Na (g) –> Na+ (g) + e-

Na+ (g) –> Na2+ (g) + e-

Question 3

What factors affect ionisation energies?

Answer 3

Nuclear charge
Atomic radius
Electron shielding

Question 4

How does NUCLEAR CHARGE affect ionisation energy?

Answer 4

As the nuclear charge increases, the force of attraction between the nucleus and outer electrons increases

INCREASING I.E.

Question 5

How does ATOMIC RADIUS affect ionisation energy?

Answer 5

As the atomic radius increases, it is easier to remove an electron as the attraction between the nucleus and outer electron is weaker

DECREASES I.E.

Question 6

How does ELECTRON SHIELDING affect ionisation energy?

Answer 6

More shells = more electron shielding, the attraction between the outer electron and the nucleus weakens

DECREASES I.E.

Question 7

How do you know which element is shown in a table of ionisation energies?

Answer 7

The number of ionisation energies before a large jump will indicate the group of an element

There would be a big jump indicating an electron is being taken away from a new shell

Question 8

Explain why the first ionisation energies show a general increase across period 2

Answer 8

Protons increase so outer electrons attract stronger thus more energy is needed to remove an electron

Question 9

Trend across period 3

Answer 9

More protons in each nucleus so the nuclear charge increases

Force of attraction between the nucleus and outer electron is increased

Question 10

Magnesium to Aluminium

Answer 10

*Look at electron configuration

The outer electron in aluminium is in a p sub-level. This is higher in energy than the outer electron in magnesium, which is in an s sub-level, so less energy is needed to remove it