Phosphorus (P)
Element 15 · Reactive nonmetal · Solid at 25 °C · Group 15, Period 3
Phosphorus is essential to life: it forms the backbone of DNA and the energy carrier ATP, and strengthens bones and teeth.
On the periodic table, phosphorus sits in group 15 — the pnictogens (nitrogen group) — in period 3. It is one of 7 elements classified as a reactive nonmetal, and at room temperature (25 °C) it is a solid.
The reactive nonmetals are a diverse family that includes hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, and selenium. They gain or share electrons in chemical reactions, forming the covalent bonds that hold molecules together. Most of the atoms in living things — including virtually all of you — belong to this category.
Properties of phosphorus
| Atomic number (Z) | 15 |
|---|---|
| Symbol | P |
| Atomic mass | 30.974 |
| Category | Reactive nonmetal |
| Group | 15 |
| Period | 3 |
| Block | p-block |
| Metal / nonmetal | Nonmetal |
| State at 25 °C | Solid |
| Electron configuration | [Ne] 3s2 3p3 |
| Electronegativity (Pauling) | 2.19 |
| Melting point | 44.15 °C (317.3 K / 111.47 °F) |
| Boiling point | 280.5 °C (553.65 K / 536.9 °F) |
| Density | 1.823 g/cm³ |
Position in the periodic table
Phosphorus shares group 15 — the pnictogens (nitrogen group) with Nitrogen (N), Arsenic (As), Antimony (Sb), Bismuth (Bi), Moscovium (Mc). Elements in the same group have the same number of outer electrons, so they tend to behave alike chemically — comparing them is one of the fastest ways to see periodic trends in action.
Physical properties
Phosphorus melts at 44.15 °C (317.3 K / 111.47 °F) and boils at 280.5 °C (553.65 K / 536.9 °F), giving it a liquid range of about 236.3 °C at standard pressure.
Its density is 1.823 g/cm³.
See also: the interactive periodic table, how to read the periodic table, periodic trends.