Question

The correct order of atomic radii of given elements is

• A. \( {B}<{Be}<{Mg} \)
• B. \( {Mg}<{Be}<{B} \)
• C. \( {Be}<{B}<{Mg} \)
• D. \( {B}<{Mg}<{Be} \)

Hint:

When comparing atomic radii, remember that atomic radius decreases as we move from left to right across a period and increases as we move down a group.

Answer 1

The Correct Option is A

The atomic radius generally increases as we move down a group in the periodic table due to the addition of more electron shells. However, when comparing elements in the same period, atomic radius decreases from left to right across the period due to increasing nuclear charge, which pulls the electrons closer to the nucleus. - Boron (B) is in Group 13 and Period 2.
- Beryllium (Be) is in Group 2 and Period 2.
- Magnesium (Mg) is in Group 2 and Period 3.
Now, comparing their atomic radii:
- Beryllium (Be) has a smaller atomic radius than Boron (B) because Be is a Group 2 element, and Group 2 elements generally have smaller radii than Group 13 elements in the same period.
- Magnesium (Mg) is further to the right in Period 3 and has a smaller atomic radius compared to Beryllium (Be).
Thus, the correct order of atomic radii is: \[ {B}<{Be}<{Mg} \]