Second Question:
I would like to clarify a few things the boiling point of group 14,15,16,17 hydrides.
I went on this link:
http://cnx.org/content/m12450/latest/ under the subtitle "Observation 3: Boiling Points of simple hydrides"
and I think this is what they're trying to say:
-as you go right on the table, the electronegativity dif between hydrogen and the element in question increases, making the element have more polar intermolecular bonds, and thus making it harder to boil. This explains why group 15 hydrides have higher boiling points than group 14 hydrides.
-as you go down on the table, the intermolecular forces decrease, which should result in a lower melting point, but this is offset by the increase in LDF forces as the molecule gets heavier. Thus boiling point increases going down the table.
Am I right?
Also, if boiling points increase going left to right then why is the boiling point of group 16 higher than that of group 17?