元素是什麼?

An element is a subatance that cannot be broken down into anything simplier by chemical method.
For example, Hydrogen and oxygen are elements while Water is not since water can be decomposed into Hydrogen and oxygen through electrolysis

ｔｈｅ　ｅｌｅｍｅｎｔ　ｉｓ　ｔｈｅ　ｓｕｂｓｔａｎｃｅ　ｔｈａｔ
ｈａｓ　ｏｎｌｙ　ｏｎｅ　ｋｉｎｄ　ｏｆ　ａｔｏｍ．
元素是不能用任何化學方法分解更簡單物質的純淨物質