Topic 1.2.2 - Periodicity

Question 1

What is atomic radii?

Answer 1

The distance from the centre of the nucleus to the boundary of the electron cloud.

Question 2

What is van der waals radius?

Answer 2

The radius where two atoms are touching and dividing the difference between the 2 nuclei by 2.

Question 3

What happens to atomic radii across a period?

Answer 3

Decreases
because nuclear charge increases meaning more attractive force between nucleus and outer electrons.

Question 4

What has higher ionisation energy helium or hydrogen?

Answer 4

Helium because it has greater nuclear charge therefore more energy required to remove electron.
This offsets the increase in electron in electron repulsion which alone would decrease heliums ionisation energy

Question 5

What happens to ionisation energy across period 2 and 3.

Answer 5

It increases as nuclear charge increases.