What is group and period in the Periodic Table?

Answer: In the periodic table, the columns are referred to as groups. An electron’s outermost shell is filled with an even number of electrons when members of the same group form the same kind of bond.

The horizontal rows of periods are called periods. An atom’s outermost shell has an arrangement of orbitals, or potential positions for its electrons, that determines its period. The progressively more electron-rich atoms in the table correlate to the successive periods of the table.