CHEMISTRY · Single correct · AP · Chemistry · Compound Structure and Properties · Compound Structure and Properties
Problem
The chlorate ion, ClO3−, can be represented by several nonequivalent Lewis structures.
Structure X: chlorine is single-bonded to all three oxygen atoms; each oxygen bears a –1 formal charge, and chlorine has a +2 formal charge.
Structure Y: chlorine is double-bonded to one oxygen and single-bonded to the other two; the two singly bonded oxygens each carry a –1 formal charge, chlorine has a +1 formal charge.
Structure Z: chlorine is double-bonded to all three oxygen atoms; all atoms have an octet and zero formal charge, but chlorine has an expanded valence shell.
Which structure is the most plausible major contributor to the resonance hybrid, and why?
(a) Structure Y, because chlorine must obey the octet rule and this structure has the fewest formal charges that still respects it.
(b) Structure Z, because it eliminates formal charges even though chlorine exceeds an octet.
(c) Structure Z and Structure X contribute equally since one minimises charge and the other obeys the octet rule.
(d) Structure X, because putting the negative charge entirely on the three electronegative oxygens makes it the most stable.