Im thinking Si has a high melting pt because each Si is covalently bonded to four other Si's And aluminium having a highest boil pt in group 3 cause it has 3 delocalised electrons and has a very small surface area? need help please
It must be because the interatomic forces are strong, this is what determines the phase of the substanceBeyond that, I'm not sure - my best guess is that it's to do with the fact that they're the farthest in the period from having a full, stable valence shell, which probably makes them tend to share electronsIn contrast, alkali metals are soft, with low melting points, halogens tend toward gaseousness, and the noble gases have very, very low boiling pointsThe surface area should be unrelated to this: Powdered Al would have the same melting and boiling point as an ingot, it would just accept heat more readily from a fluidAs for bonding, remember that Al has a metallic bond with it's neighborsSi is not covalently bonded in the traditional sense, forming molecules (like P or S) but is more of a crystal structure - it's sort of a broad affinity for other atoms like itWhich brings us back to having a valence shell half-full, and sharing electrons.
