The exact position of the electron cannot be determined, but only with a certain probability at any point in space. An electron has a fixed energy and a certain spatial distribution. This distribution is called the orbital.
We will give an explanation only for the atomic orbital. An atomic orbital is a one-electron wave function that describes the behavior of electrons in an atom.
How does a molecule of atoms bind? So that’s it. When a molecule is formed, the binding of two atoms occurs through electrons located in the atomic orbital. That is, valence electrons are electrons that are located on the valence layers of an atom. In other words: valence is something like the ability to bind atoms into a molecule.
If we consider the electronic formula of hydrogen (1s1), we will see that it has only one electron in its valence orbital. Therefore, its valence is equal to one.
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