Answer
a. Atomic radius within this group tends to include when moving down the group. The reason is that, as we move down, more energy levels are filled with electrons, each bigger than the previous, making the atom larger.
b. Ions are smaller than the atoms in group 1A because electrons are lost in order to form cations. The lost electron, removed from the outer orbital of the atom, leaves an empty space, more specifically a whole s energy level empty, thus reducing the size of the atom.
Work Step by Step
a. Atomic radius within this group tends to include when moving down the group. The reason is that, as we move down, more energy levels are filled with electrons, each bigger than the previous, making the atom larger.
b. Ions are smaller than the atoms in group 1A because electrons are lost in order to form cations. The lost electron, removed from the outer orbital of the atom, leaves an empty space, more specifically a whole s energy level empty, thus reducing the size of the atom.