The main trends - Chemistry Unit 1

Properties

What happens as we go down a group?

What happens as we go across a period?

Ionisation Energy

Decrease

• More electrons are added to the atoms.
• More shells created.
• The outer electrons are shielded from the nucleus.
• Less attraction and it is easier to remove them

Increase

• Number of protons increases.
• Stronger positive charge in the nucleus.
• More attraction between nucleus and electrons.
• More energy needed to remove the electrons.

o Between Mg and Al, the IE decreases.

o The outer electron in Al is found in the 3p orbital.

o Slightly higher energy than 3s orbital (like Mg).

o Less energy is needed to remove the electron.

§ Between P and S, there is a drop.

§ In the 3p orbital of P, there is only one electron in each.

§ In the…