This balance must occur in all chemical reactions in nature. The intermolecular and inter-atomic forces that hold the atoms and molecules together or keep electrons spinning around the nucleus are also in equilibrium. The repulsive electrical force that would hurl the electron out of the atom is balanced by the gravitational force of the nucleus attracting the electron to the atom. The atom thus maintains its configuration because of the balance of those two opposing forces. The bonds that hold atoms together to form stable compound molecules, such as salt or water, maintain a balance of positive and negative charges.
Sevenfold divisions appear again and again in the cycles of nature.
There are seven groups, or columns, plus an eighth group of chemically-inert noble gases. All the elements in the same column have similar chemical properties. There is a periodicity that guides the behavior of the elements in other fundamental chemical processes. Electrons do not whirl around the nucleus chaotically but follow seven distinct paths or orbitals. Each orbital can hold a definite number of electrons.