Which of the following best explains why all three N–O bonds in the nitrate ion,
CHEMISTRY · Single correct · A Level · Chemistry · Bonding · Bonding
Problem
Which of the following best explains why all three N–O bonds in the nitrate ion, NO3−, are identical in length and shorter than the N–O single bond in nitrite, NO2−?
(a) Nitrogen can expand its octet in NO3− by using empty d orbitals, allowing it to form three N=O double bonds of equal length.
(b) Formal charges place a −1 charge on each oxygen in NO3−, forcing every N–O linkage to behave as a full double bond and making them all identical.
(c) Resonance delocalizes one π bond over the three N–O connections in NO3−, so each bond has a bond order greater than one and identical, shortened lengths.
(d) The three canonical forms of NO3− alternate rapidly, so measurements detect a time-averaged mixture of one double and two single bonds that appears as three equal bonds.