Trend in first ionisation energy down a group

https://www.youtube.com/watch?v=s8XqX3UhPOo

What happens to first ionisation energy as we go down the group

It decreases.

Due to atomic radius increase, so outer electron shell further away from nucleus.

Going down a group, the number of internal electron shells also increases, so more shielding between the nucleus and outer electrons

What do u have to notice about the successive ionisation energy graph about oxygen / any element

Theres a gradual increase in ionisation energy as we remove first six electrons

This is because each time we remove an outer electron , the remaining electrons in the outer shell are pulled slightly closer to the nucleus. so greater attraction between outer electrons and nucleus.

There is massive increase when we remove seventh electron, because the first six electrons in outer shell, once these electrons are removed, the seventh electron removed from first shell

The first electron shell closer to nucleus, electrons in first shell experience much less shielding, so electrons in first shell have greater attraction to nucleus,

How to work out element from ionisation energy graph in period 3

Work out number of electrons in outer shell, the ionisation energy gradually increases up to the fourth ionisation, massively increases at ionisation number 5.

So 4 electrons in outer shell, fifth was removed from internal shell, must be group 4

Element in group 4 period 3 is silicon.

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