Although there are any number of possible methods by which electrons and protons might be grouped, they assemble in specifi c atomic combinations for a stable arrangement. (An atom is the smallest particle of the basic elements which forms the physical substances we know as solids, liquids, and gases.) Each stable combination of electrons and protons makes one particular type of atom. For example, Fig. 1–2 illustrates the electron and proton structure of one atom of the gas, hydrogen. This atom consists of a central mass called the nucleus and one electron outside. The proton in the nucleus makes it the massive and stable part of the atom because a proton is 1840 times heavier than an electron.
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| Figure 1. Electron and proton in hydrogen (H) atom. |
In Fig. 1, the one electron in the hydrogen atom is shown in an orbital ring around the nucleus. To account for the electrical stability of the atom, we can consider the electron as spinning around the nucleus, as planets revolve around the sun. Then the electrical force attracting the electrons in toward the nucleus is balanced by the mechanical force outward on the rotating electron. As a result, the electron stays in its orbit around the nucleus.
