The differences between periods and groups are as follows:
Periods | Groups |
Horizontal rows of periodic table are called periods. | Vertical Columns of periodic table are called groups. |
In a period from left to right, elements change their characters gradually. | In a group from top to bottom elements have same characters. |
Size of the atoms decrease from left to right in period. | Size of the atom increases from top to bottom in a group. |
Valency of elements increases first up to group IV an then decreases up to Group O. | Valency of elements remains same in a group. |