Understanding atoms is key to understanding the physical world. More than 100 different elements exist in nature, each with its own unique atomic makeup. The atoms of these elements react with one another and combine in different ways to form a virtually unlimited number of chemical compounds. When two or more atoms combine, they form a molecule. Millions of molecules join together to make up the cells in humans or in any other plant or animal.
- atom [ˈætəm] n.原子
- element [ˈelimənt] n. 元素
- unique [ju:ˈni:k] adj. 独特的
- makeup [ˈmeikʌp] n. 结构
- react [riˈækt] v.起反应
- combine [kəmˈbain] v. 结合
- virtually [ˈvə:tʃuəli] adv.实际上
- compound [ˈkɔmpaund] n. 化合物
- molecule [ˈmɔlikju:l] n.分子
- cell [sel] n.细胞
- make up [meik - ʌp] v. 构成，组成
