Question

which atom has the smallest covalent radius? b c n si p

Explanation:

• Atomic radius trends: In the periodic table, atomic (and covalent) radius decreases across a period (from left - to - right) due to increasing nuclear charge which pulls electrons closer. It increases down a group due to the addition of new electron shells.
• Position of elements: B (Boron), C (Carbon), N (Nitrogen) are in the second period. Si (Silicon) and P (Phosphorus) are in the third period. Since elements in the third period have an extra electron shell compared to those in the second period, Si and P will have larger covalent radii than B, C, and N.
• Comparison within the second period: Among B, C, and N (second - period elements), as we move from B (atomic number \(Z = 5\)) to C (\(Z=6\)) to N (\(Z = 7\)), the nuclear charge increases. The electrons are in the same \(n = 2\) shell. The increased nuclear charge attracts the electrons more strongly, reducing the covalent radius. So, \(B>C>N\) in terms of covalent radius.

Answer:

N