I unfortunately have to admit that I have never seen a diamond melt, and I’m not sure I’ll get a chance to witness such an event. However, with all the snow flurries today, we can all say that we have seen the phenomenon of ice and/or snow melting! In class today we learned that ice is not just bound by a network of H bonds, but a composite of covalent bonds (O-H in the actual water molecule) and H bonds (attraction of O of one molecule to H on another molecule). The fact that H bonding is a component of its solid crystal formation explains why the melting point for ice is much, much lower, relative to diamonds.
Because of this, I was wondering how snow, which is a form of frozen water, differs from ice. I don’t think it would differ chemically, but surely something about the two frozen forms must be different, because they appear so different to us as observers, in terms of shape and size. Even snow can come in multiple ‘forms’ – it can be delicate, soft, fluffy, clustered, tiny….and anything in between. I was wondering how the chemical structures of these different forms of frozen water are different, if at all.
I looked up some articles online, and got a small sense of how snowflakes form! Snow forms from water vapor in clouds, but can encounter many obstacles on its journey down from the sky. Because each snowflake embarks on a different journey, so to speak, it will form different crystal structures that we can delight in here on the ground. For example, if snowflakes form in colder temperatures, they will produce lacy, delicate hexagonal snowflake shapes. If snowflakes are formed in warmer temperatures, the snowflake forms more slowly, which unfortunately means less elegant structures. The presence of dust particles also can affect crystal durability. Furthermore, since weather can fluctuate, a water vapor can undergo snowflake formation, can partially melt, and reform multiple times before it hits the ground.
However, if I interpreted it correctly, all these beautiful structures still are the result of good old hydrogen bonding. These H bonds are often responsible for the symmetrical shape of snowflakes because that represents the most ordered internal structure of the freezing water vapor. The process of crystallization, with the help of H bonds, aligns water molecules in the most favorable way, resulting in the delightful structures we see.
My second question I’m posing, inspired by our discussion of melting in class today – Why is water wet? This question is a little more philosophical than biochemical, since I think wet is a description we assigned to the sensation of feeling liquid things, but I thought the responses to this question (in link below) were very satisfying because it again emphasizes how differently people can respond to a probing but ultimately simple question.
http://www.theguardian.com/notesandqueries/query/0,5753,-1725,00.html