Topic 2- Electronic Structure

Question 1

Define “The first ionisation energy”

Answer 1

The first ionisation energy is the energy needed to remove one electron from each atom in a mole of gaseous atoms of an element to form one mole of gaseous ions with a single positive charge.

Question 2

What are the three factors affecting ionisation energies?

Answer 2

• Nuclear Charge
• Atomic Radius
• Electron Sheilding

Question 3

How does nuclear charge effect ionisation energies?

Answer 3

The greater the nuclear charge the greater the attractive force experienced by outer electrons.

Question 4

How does atomic radius effect ionisation energies?

Answer 4

The greater the radius the smaller the nuclear attraction experienced by the outer electrons.

Question 5

How does electron shielding effect ionisation energies?

Answer 5

• The inner shell electrons repel the outer electrons
• The repelling effect= electron shielding
• The more inner electrons, the greater the shielding effect and the smaller the nuclear attraction experienced by the outer electrons

Question 6

Define “the second ionisation energy”

Answer 6

The second ionisation energy is the energy needed to remove one electron from each ion in a mole of gaseous +1 ions to form a mole of gaseous 2+ ions”

Question 7

What are successive ionisation energies?

Answer 7

A measure of the energy required to remove each electron in turn.

Question 8

What are the trends of ionisation energy in the periodic table?

Answer 8

• As you go across there is an increase in ionisation energy

- As you go down there is a decrease in ionisation energy

Question 9

As you go down a group in the periodic table, what happens to the ionisation energy trend and why?

Answer 9

It decreases. This is because the number of shells, shielding and atomic radiuses increases and the first ionisation energy decreases.

Question 10

As you go across a period, what happens to the ionisation energy and why?

Answer 10

It increases. This is because the atomic radius decreases whereas the number of protons and the first ionisation energy increases.

Question 11

Each shell (n) consists of a number of sub-shells. How many sub-shells are there and what are they called?

Answer 11

There are 4 sub-shells:

• s
• p
• d
• f

Question 12

Each energy level (n) contains sub shells. What does each sub-shell contain?

Answer 12

A set of orbitals which each hold 2 electrons.