英语时差：活化能，火，燃烧棒（上）

Here’s one you probably never thought to ask about before. You’re in the woods building a campfire. You pile up some dry kindling and light a match. Hold the match under the kindling and, sure enough, the kindling starts burning. Okay, so why is that? You held a burning stick up to a non-burning stick. Why Do You Now Have Two Burning Sticks? The answer is in the nature of fire. If you could look at a flame with super-penetrating vision, you’d see that on an atomic level what you have is the rapid combination of carbon and hydrogen atoms in the wood and oxygen atoms in the air. Given a chance, these atoms will link up to form molecules, such as carbon dioxide and hydrogen dioxide. When this happens, energy is released. That energy causes the light and heat that we see and feel when sitting around a campfire.