Hi,
I just had a quick question. Im looking over the orgo section right now. And I noticed that all of the electron donating groups that were the strongest also had some of the stongest electronegative atoms(ex: -O, -OH). Is is safe to assume that in general that strong electronegative atoms also will be strong electron donators? This might be a dumb question, but I had to ask ne way.
No, not necessarily. Fluorine, chlorine, etc. are strongly electronegative but are only weak electron donors.
There are really two factors at play here, which cause confusion.
1) sigma-acceptor ability : this correlates directly with electronegativity, and is a matter of how much electron density the element "sucks out" of a covalent sigma bond it's attached to. F, Cl, N, O, etc. all have electronegativities greater than that of C and therefore are net sigma acceptors.
2) pi-donation ability: this corresponds to an element having a Lewis basic electron pair that is able to donate into a neighbouring atom and form a pi bond. This is a donating effect. -NH2, O- , OH, OR, etc. are all good pi donors. The lone pairs of halogens (F, Cl, Br, etc) are weak Lewis bases and only weak pi donors.
In aromatic substitution, pi donation is a more powerful effect than sigma donation. Hence, amines and alcohols are strongly activating, and they direct electrophilic aromatic substitution ortho-para. Halogens are deactivating (due to sigma acceptor ability) but are ortho-para directing (due to pi donation ability). hope this helps.