Explaining Trends THE PERIODIC TABLE

Question 1

Why does the reactivity of group 1 metals increase as you go down the group?

Answer 1

The atoms get larger, therefore the electron in the outermost shell is attracted less strongly to the positive nucleus. The electrostatic attraction between the oppositely charged outer electron and the nucleus is weakened.

The shells increase as you go down the group. This creates a shielding effect. They block the positive charge of the nucleus. Therefore, making it easier for the atom to lose the one electron.

Question 2

Why does the reactivity decrease as you go down group 7?

Answer 2

These atoms need to gain electrons. The outer shells get further away from the positive charge of the nucleus as you move down the group, making the electrostatic force less. Therefore, it is difficult for the atoms to gain the electron that they need.

The outer shells are shielded by inner shells, reducing the electrostatic attraction of the nucleus for an incoming electron