Question

which of the bonds in the following groups, i - ii, has the shortest bond length?
group i: s - f, s - br, s - cl group ii: c≡n, c≡o, c≡c
a. s - br, c≡c b. s - f, c≡o c. s - f, c≡n d. s - br, c≡o
e. s - cl, c≡o

Explanation:

Step1: Analyze Group I

Bond length is inversely related to the electronegativity difference and atomic radius. Among \(S - F\), \(S - Br\), \(S - Cl\), \(F\) has the smallest atomic radius (\(F\) is in period 2, \(Cl\) in period 3, \(Br\) in period 4). Smaller atomic radius leads to shorter bond length. So in Group I, \(S - F\) has the shortest bond length.

Step2: Analyze Group II

For triple - bonds \(C\equiv N\), \(C\equiv O\), \(C\equiv C\), the bond length also depends on the electronegativity of the atoms. \(O\) is more electronegative than \(N\) and \(C\). The more electronegative the atom, the more it pulls the electron cloud towards itself, resulting in a shorter bond length. So in Group II, \(C\equiv O\) has the shortest bond length.

Answer:

B. \(S - F\), \(C\equiv O\)