2. Well, this one if much tougher than the first one. The short answer is: We scientist do not have yet a really good explanation to this fact. All we know is that the attractive forces between mercury atoms are weaker that those in their neighbors. Since this question is often asked by many students, in a service similar to Scienceline offered by the scientists at Argonne National Laboratory I found a couple of interesting answers, please follow the link to:
click here

Hope to have helped you a little in getting a better understanding of the wonderful universe in which we live!