Читать книгу Foundations of Chemistry - Philippa B. Cranwell - Страница 62

Electrons are arranged outside the nucleus of the atom in energy levels that are sometimes called principal quantum shells. You can imagine these as spherical layers extending out from the nucleus as in Figure 1.4. The energy levels are numbered from 1 to 7, with the level closest to the nucleus being level 1. These numbers are referred to as the principal quantum number of the electrons in that energy level. The principal quantum number has the symbol n. As the distance from the nucleus gets bigger, the volume of the layers increases. In addition, as the distance from the nucleus increases, the energy of the level increases along with the energy of the electrons in the level. The seven principal quantum levels relate to the seven rows across the periodic table.

Figure 1.4 The energy levels (EL) in an atom. The integers represent the principal quantum number, n.