Читать книгу Geology For Dummies - Alecia M. Spooner - Страница 76

All matter is made of atoms. Every single speck of gas, liquid, or solid surrounding you is a mix of millions of atoms. An atom is the smallest bit of matter that can be measured and identified as a specific element.

Atoms themselves are composed of smaller, subatomic particles called neutrons, protons, and electrons. Figure 5-1 is a diagram of atomic structure, including the location of each different subatomic particle type. Protons and neutrons are located in the nucleus at the center of the atom. In each atom, the electrons surround the nucleus, organized into orbital shells. The innermost orbital shell of any atom contains no more than two electrons; the second orbital shell contains no more than eight; and each of the outer shells, while chemically stable with eight electrons, can hold more.

FIGURE 5-1: The parts of an atom.

The number of protons in an atom’s nucleus determines which element the atom is. For example, an atom with six protons is an atom of the element carbon. An atom with seven protons is an atom of nitrogen.