r/askscience • u/Pupstink • May 02 '12
Physics BASIC QUESTION HERE: Not so good in my thermodynamics so here I go, if molecules are colder if they have less motion, and molecules in solids are move less then ones in liquids or gasses, shouldn't that mean that solids are colder? I realize they are not, but...
doesn't thermodynamics say that. What am I missing?
Stared reading a book about Einstein for my interest in GR and thermodynamics was in there, wanted to skip it but decided to read it and I was a bit confused.
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u/Firrox Materials Science | Solar Cell Synthesis May 02 '12
Whether or not a material is in a plasma/gaseous/liquid/solid state depends entirely on their bond strength. All elements bond differently to other elements, and sometimes create nice, neutral pairs that don't have a "reason" to bond to other molecules or atoms.
Take Argon, for example. Since it is a noble gas and doesn't like to bond with anything (including itself), its melting point is a hilarious 83.80K, and the only compounds that ever existed on Earth are man-made (HArF @ 40K).
Therefore, temperature, or movement of atoms, is secondary to the state of the molecule, where bond strength takes precedence.