Periodicity

Question 1

What’s the definition of periodicity?

Answer 1

The repeating units of physical and chemical properties

Question 2

What happens to the atomic radius down a group?

Answer 2

It increases going down the group.
There is extra energy levels as there’s more electrons.
This means that there’s more shielding
The attraction to the nucleus decreases

Question 3

What happens to the atomic radius across a period?

Answer 3

It decreases across a period
Number of protons increases
Same energy level
Same shielding
Attraction to nucleus increases

Question 4

What’s the definition of ionisation energy?

Answer 4

The energy required to remove 1 mol of gaseous atoms.

Question 5

What happens to the first ionisation energy down the group?

Answer 5

• Ionisation energy decreases
• The electron is moved from a higher principle energy level
• The outer electron is further from the nucleus
• There is more shielding
• Weaker attraction between the nucleus and outer electron.

Question 6

What generally happens to the first ionisation energy across the periods?

Answer 6

• Ionisation energy increases
• the number of protons increase
• Shielding is constant / atomic radius decreases
• Stronger attraction between nucleus and outer electron

Question 7

What are the exceptions to the ionisation energy rule?

Answer 7

• Between group 2 to group 3 the ionisation energy decreases as the electron is removed from a higher energy p subshell so there is a weaker attraction between the nucleus and the outer electron

Question 8

Why is the first ionisation of S less than that of P?

Answer 8

The ionisation energy decreases
There is a pair of electron s in a p orbital
Extra repulsion means less energy is required to remove outer electron
(this is the same for group six)

Question 9

What is metallic bonding?

Answer 9

Strong electrostatic attraction between positive ions and delocalised electrons

Question 10

What factors affect the strength of a metallic bond?

Answer 10

• Ionic charge on the metal (higher = stronger)
• The number of delocalised electrons (more = stronger)
• The atomic radius (smaller = stronger)

Question 11

What are the properties of metals?

Answer 11

• Good conductors of electricity and heat.
• Very high melting and boiling point as they have a strong electrostatic attraction between the positive ions and the delocalised electrons.
• Metals are malleable and ductile meaning that they can be hammered into shape due to the layers of ions that can slide over each other.