Question 17

[quadalpha]

Perhaps the question can be amended to say "at least one lone pair"? It would not be impossible, for instance, if P only had the one lone pair of valence electrons which is hybridised to give two orbitals and linear shape.

[mcat_premed3832]

The expression "lone pair of electrons" refers to what an atom possesses within a molecular environment. It does not mean what at atom possesses when the atom is alone.

www.absoluteastronomy.com/topics/Lone_pair

[quadalpha]

[mcat_premed3832]

Sorry for not linking the 2 ideas . . .

So this is from the link: "A lone pair is a (valence) electron pair without bonding or sharing with other atoms. They are found in the outermost electron shell of an atom, so lone pairs are a subset of a molecule's valence electrons"

AND

"Thus, the number of lone electrons plus the number of bonding electrons equal the total number of valence electrons from a compound." Wikipedia (http://en.wikipedia.org/wiki/Lone_pair)

So when you are talking about a lone pair of electrons on an atom within a molecule, for sure that atom has more valence electrons that just the lone pair (otherwise it could not bond). This is why it is not necessary to specify that there are at least a lone pair of electrons on the atom.