The vertical column in modern periodic table is known as group
1) no of valence electrons is the same in a group.
2)no of occupied shells increases down a group.
3)size of atoms increases because no of shells increases
4)metallic character of atoms increases because the electrons are fairly far away from the nucleus as the size increases.So it is easier for the heavier elementsto lose electrons .Hence they are more metallic.
5) Effective nuclear charge decreases down the group.
This is due to shielding effect by the inner electrons.It essentially means that due
to the presence of these electrons,outer electrons are less exposed to nuclear
attraction.So,the net nuclear force of attraction on them decreases,as they're far
away from the nucleus.