[p3t3r1]

Hi, this question really puzzles me. I read a whole bunch of ttextbooks and they didn't mention much.

Aluminum has a boiling point of 2519 c while zinc has a boiling point of 907 c. They are both metallic bonds. Which means:

1) The higher the positive charge, the smaller the metallic bond.(electron sea more attracted.) Zinc has a charge of 30 while aluminum has only 13.

2) the greater number of valence electroncs, the stronger the bond. Zinc has +2 while AL has +3. Now this could be the factor but it doesn't seems like to be the ONE. The fact that zinc has 1 more valence electron shouldn't make that much of difference.

3) The packing cordination: Zinc and AL have the same number.

Can one factor really affects that much? Or I am missing something? Thanks. Btw, Zinc is weird because all the element before it have  high b.p but when it comes to zinc, it drops down like crazy.

[enahs]

If you follow the same evaluation of trends for Cadmium and Mercury you will see the same general pattern.

Notice their position on the periodic table.

Simple answer is because of the high polarizability of the filled d shell.

More then likely you will not study this until Inorganic chemistry in college, and I believe a more detailed discussion is out of context for a high school forum.

If you are that interested and up for a challenge, if you get any Inorganic chemistry book it will have a whole chapter devoted to just Zinc, Cadmium and Mercury.

[p3t3r1]

I see. Thanks. I went through 4 textbooks and found nothing. 

[enahs]

I see. Thanks. I went through 4 textbooks and found nothing. 

It is not a simple thing (and I doubt it is in any general chemistry book). It just makes smart inquisitive people like you ask the teacher/professor question that can not be really answered based on the knowledge you have so far.

Interesting thing FYI, many (if not most) Inorganic chemist refer to Zn,Cd and Hg as a set of the main group elements and not transition. That should clue you into their importance.