Question 3.55

[Annah Khan 1B]

"Which of the following species are radicals?
(a) NO2-
(b) CH3
(c) OH
(d) CH2O"

I was having trouble answering this question. If someone could help me answer the question and explain to me why that is the answer, I would really appreciate it.

[204580382]

A & D are not considered radicals since their octects are complete.
B & C are considered radicals.


CH3 has a total number of 7 valence electrons. WHen drawing out the Lewis structure one can notice that one electron is not bonded. Since all hydrogen has their bond and carbon does not, its octet is not complete. Thus CH3 is a radical.


OH has a total number of 7 valence electron. The same condition with B, but oxygen does not have its octet complete, therefore OH is a radical

[504754253]

to clarify, a radical is an unpaired electron... with the exception of those elements that are exception to the octet rule it must complete the octet rule in order to not be seen as a radical (sorry if this is more confusing )!!

[504754253]

"Radicals are species with an unpaired electron, therefore only (b) and (c) are radicals since they have an odd number of electrons while (a) and (d) have an even number of electrons allowing Lewis structures to be drawn with all electrons paired." SOLUTIONS MANUAL

[Ivan Huang Dis 3B]

the odd-numbered answers on the back matter say that A and B are the only radicals. Is this answer wrong because I also only got B and C are radicals

[705573518]

the odd-numbered answers on the back matter say that A and B are the only radicals. Is this answer wrong because I also only got B and C are radicals

I got the same answer as you. I think it is just a mistake in the solutions.