Donald Sadoway is a professor of materials science and engineering at MIT. Over the last few years he has emerged as one of the most popular lecturers on campus. Even Bill Gates has referred to him as a fantastic chemistry teacher. His course titled "Introduction to Solid-State Chemistry" is so much in demand that in 2007 it had about 600 students and the school had to stream the lecture into another room. Fortunately all his lectures including the ones for 2010 are online. Sadoway is a great speaker and seems to have thought very carefully about what he wants to say in class. Definitely worth watching.
Check out his description of the structural differences between diamond and graphite and how they affect the radically different properties of the substances. It's one of the clearest explanations of the difference I have heard.
At the end, Sadoway mentions that since graphite is the most stable form of carbon at room temperature, wouldn’t it make sense to present a ring made of graphite instead of diamond to your love interest as a symbol of everlasting love? I think that makes sense although my fiancée will probably disagree.
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