Question

The correct decreasing order of the atomic radii of the elements sodium, magnesium and aluminium is:

• A. Magnesium > Sodium > Aluminium
• B. Sodium > Magnesium > Aluminium
• C. Magnesium > Aluminium > Sodium
• D. Aluminium > Sodium > Magnesium

Answer 1

The correct option is B Sodium > Magnesium > Aluminium

The atomic radius decreases on moving from left to right along a period due to an increase in effective nuclear charge which results in pulling of electrons towards the nucleus.
As the atomic radius decreases from left to right along a period, hence the correct decreasing order of atomic radii is :
Sodium > Magnesium > Aluminium