In “What exactly is fire?”, part of Wenhsingyu’s question is:
Cecil answers:
While almost all of Cecil’s answer is correct as usual, fire can be ionized, and used as both a rectifier and an amplifier with the addition of electrodes. Flame rectifiers even make use of electrodes coated with salt in order to inject additional ions into the flame.
Source:
Fire, on the other hand, is a kind of exothermic oxidation reaction.
The reaction that makes the Sun bright is nuclear: It involves atomic nuclei physically slamming together at extremely high speeds and liberating massive amounts of energy. This destroys atoms and creates new ones.
The reaction you see when a candle burns is chemical: It involves valence shell electrons jumping from atom to atom and liberating rather small amounts of energy in the process. The atoms themselves are largely unchanged.
I like to think of atoms as small stones surrounded by cotton candy: The cotton candy is the electron cloud, the small stone is the nucleus. A chemical reaction is all about the edges of the ‘cotton candy’ of two or more atoms touching, whereas a nuclear reaction involves the little stones changing in some fashion.
(Fun fact: Most of what you think of as solid matter is really empty space. Very little of the volume of an atom is filled by the nucleus, leaving the electrons as tiny little particles buzzing around in a relatively huge empty volume. How empty? Well, the nuclear reactions in the Sun produce tiny little electrically neutral particles called ‘neutrinos’; approximately 65 billion of the little buggers pass straight through every square centimeter of the side of the Earth facing the Sun every second, like they were peas being shot through a thin fog. The majority of them never interact with anything.)
Of course, since most of the neutrinos never interact with anything, they come right out the other side of the Earth, so they pass through the side of the Earth facing directly away from the Sun at very, very close to the same rate.
Also: Neutrinos have mass. They have to, or else we can’t explain how many we actually observe the Sun producing. So this isn’t quite the same as radio waves passing through; it’s tiny little hunks of matter finding a path right in between the solid parts of all of your atoms, all of the Earth’s atoms, and so on.