First ionisation energy down group 2
After studying this page, you should be able to:
- describe and explain the trend in atomic radius down group 2.
First ionisation energy
The table shows first ionisation energy values for the common elements in group 2.
|Element||Symbol||Atomic number||First ionisation energy /kJ mol–1|
Description of the trend
The graph shows how the first ionisation energy varies down group 2:
- as you go down group 2, the first ionisation energy decreases.
Explanation of the trend
Going down group 2:
- there are more filled shells between the nucleus and the outer electrons …
- these shield the outer electrons from the attraction of the nucleus …
- the radius of the atom increases, so the distance between the nucleus and the outer electrons increases …
- therefore the force of attraction between the nucleus and outer electrons is reduced …
- so less energy is needed to remove an outer electron.