How groups are there in the modern periodic table?

Answer 1

The group number tells you the number of valence electrons in the outer shell. This is important because it is the valence electrons that participate in bonding, and thus in determining the properties of the element.

Answer 2

On the modern Periodic Table there are 18 groups and 7 periods. Mendeleev's periodic table only contained 63 elements and did not list the atomic number of the element.

Answer 3

The vertical columns on the periodic table are called groups. There are 18 groups on the periodic table.