Question

The single-bonded metallic radius of $Na$ is $157$ pm. Give a reasonable estimation of the radii, assuming that the increment between radii of different magnitudes is $60$ pm. The covalent radius of $Na$ is:

• A. $157$ pm
• B. $164$ pm
• C. $137$ pm
• D. $97$ pm

Answer 1

Answer: (D)

$97$ pm

The metalllic radius is always greater than the covalent radius as the metallic forces are weaker than the covalent forces.
The metallic radius is $157$pm and the increment between radii of different magnitudes is $60$ pm. Hence, the covalent radius of $Na$ is $157pm-60pm=97pm$