Berilium and Al are placed in different periods and groups but they show the similar properties.Why ?

Q: Berilium and Al are placed in different periods and groups but they show the similar properties.Why ?

Solution: On moving across a period the charge on the ions increases and the size decreases, causing the polarising power to increase. On moving down a group the size increases and polarising power decreases. On moving diagonally i.e., from Be to Al these two effects partly cancel each other and so there is no marked change in properties.