8.1 - 8.4 Periodicity

Question 1

Describe the reactivity of metals

Answer 1

More reactive going down a group

Question 2

Describe the reactivity of non-metals

Answer 2

More reactive going up a group

Question 3

Describe the reactivity of transition metals

Answer 3

Relatively unreactive

Question 4

Describe the type of elements in period 3

Answer 4

Na, Mg, Al = Metals
Si = Semi-metal
P, S, Cl = Non-metals
Ar = Noble gas

Question 5

Describe and explain the trend in melting and boiling points of group 3 elements

Answer 5

Sodium -> Aluminium = Increase:

• Strength of metallic bonding
• Increases as the number of delocalised electrons increases

Silicon = Highest:
- Giant structure

Non-metal boiling points = S₈ > P₄ > Cl₂:

• Van der Waals decrease with the number of electrons
• Electrons decrease with size of molecule

Argon = Lowest

Question 6

Describe and explain the trend in atomic radii across group 3

Answer 6

Decrease moving right:

• No. of electron shells in use and shielding stays the same
• Atomic charge increases

Question 7

Describe and explain the trend in atomic radii down a group

Answer 7

Increase going down:

• No. of electron shells in use and shielding increase
• This overrides increase in atomic charge

Question 8

Describe and explain the trend in first ionisation energy going across a period

Answer 8

Increases:
- No. of electron shells in use and shielding stays the same
HOWEVER…
- Atomic charge increases

Increasing amount of energy is required to remove outer electron

Question 9

Describe and explain the trend in first ionisation energy going down a group

Answer 9

Decreases:

• No. of electron shells in use and shielding increase
• This overrides increase in atomic charge

Decreasing amount of energy is required to remove outer electron

Question 10

Why is there a drop in ionisation energy from one period to the next?

Answer 10

Decreases:

• No. of electron shells in use and shielding increase
• This overrides increase in atomic charge

Decreasing amount of energy is required to remove outer electron

Question 11

Describe and explain the irregularities to the first ionisation energy trend in group 3

Answer 11

Drop from 2 to 3:

• P-electron is in a higher energy level than the s-electron
• So it takes less energy to remove

Drop from 5 to 6:

• In 6, two p-electrons are paired
• The paired electrons repel each other
• So it takes less energy to remove

Question 12

Describe and explain the trend in successive ionisation energies

Answer 12

• Each electron is harder to remove than the last

- There is a big increase in the amount of energy needed for electrons in each shell as you get closer to the nucleus