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Q & A: heating particles

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Most recent answer: 12/14/2009
Q:
What happens to the atoms or molecules when heat is supplied? I mean, how do they contract or expand with change in temperature? Please explain it at microscopic level. THANKS
- Apurva (age 17)
A:
Let's say you heat up a gas of many atoms. Some of that heat goes into making the atoms move around faster. When the temperature gets high enough, the electrons in the individual atoms will occasionally go into higher-energy states, not just the lowest-energy ground states. Some electrons will hop off the atoms altogether, leaving a partly ionized plasma.

The same things happen for molecules, along with some other processes. At fairly low temperatures, the molecules start to rotate. A little hotter, and they start to vibrate in various ways.  The molecules themselves can fall apart when they're hot enough.

If the atoms or molecules are packed together in a solid or liquid, still more things happen, but maybe that's all you need for now.

Mike W.

(published on 12/14/2009)

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