Phosphorus has 5 valence electrons. Valence electrons are the electrons in the outermost shell of an atom that are available to participate in chemical bonding. Phosphorus is in group 5A of the periodic table, which means that it has 5 valence electrons.
The electron configuration of phosphorus is [Ne]3s23p3. This means that the outermost shell of phosphorus has 2 electrons in the 3s orbital and 3 electrons in the 3p orbital. The 3p orbital can hold up to 6 electrons, so the 3 electrons in the 3p orbital are the valence electrons.
Phosphorus can form bonds with other atoms by sharing its valence electrons. For example, phosphorus can form a single bond with each of the 3 oxygen atoms in a molecule of phosphorus trioxide (P4O6). In this molecule, each phosphorus atom shares its 3 valence electrons with the 3 oxygen atoms, and each oxygen atom shares its 6 valence electrons with the 3 phosphorus atoms.
