RE: Why does aluminum foil not get hot when it is in a hot oven?
aluhm > 04-28-2018, 07:51 AM
Hmmmm. I don't know what kind of fancy aluminum foil you've been using, Nicole, but aluminum foil gets really hot in my oven. To understand why this happens, it's good to know what "temperature" and "heat" really mean. Everything is made of molecules and atoms, and all atoms are made of a very heavy nucleus with a bunch of small electrons orbiting around it like moons.
The temperature of an object tells you how fast the molecules in that object are moving. When something gets really hot, its molecules get moving around really fast. When you heat up a liquid (like water), the liquid molecules start moving so fast that they stop sticking together, and they change from a liquid into a gas (this is what happens when water boils). The same thing happens when you heat up a solid (like ice) -- the molecules stop sticking together, and the solid melts into a liquid. Most of the things you use every day will melt inside an oven -- think of ice, or glass, or plastic things (please don't try to experiment with melting things in your oven!). That's because the molecules making up those things are held together pretty weakly.
But metals, like aluminum foil, are different. Instead of being made of lots of individual molecules, atoms are one big block of nuclei that all share electrons with each other.
You can think of it like this: most materials (like plastic) are like a bunch of grapes -- each nucleus is weakly attached to the others by a tiny little stem. It's easy to cut the stem or knock off a few grapes if you bump into the bunch, and if you shake the bunch, all the grapes move around in different ways. But the nuclei in metal are more like the grapes in a Jell-O fruit cocktail. They're all linked together by a goop of electrons (the Jell-O), it's tough to get just one grape out without pushing a bunch of the jello around and making a big mess, and if you shake the jello, all the grapes bounce in the same way.
So when you heat up a metal, the goop of electrons (physicists call it the 'sea' of electrons) can start getting hot and moving really fast, but all the nuclei stay in the same place and just pass the electrons back and forth amongst themselves. So a metal can get really, really hot before it gets so hot that the nuclei stop sticking together. That's why you can put your aluminum foil in the oven and it will get hot, but you won't be able to turn up the heat enough to melt it.