Phosphorus (P) – element 15
Phosphorus is a chemical element with the symbol P and atomic number 15. It is a reactive nonmetal in group 15 (pnictogens), period 3 of the periodic table (p-block), and is a solid at room temperature.
Phosphorus (P) has atomic number 15, atomic mass 30.974 u and electron configuration [Ne] 3s2 3p3.
Phosphorus facts
| Symbol | P |
|---|---|
| Atomic number | 15 |
| Atomic mass | 30.974 u (g/mol) |
| Category | reactive nonmetal |
| Group | group 15 (pnictogens) |
| Period | 3 |
| Block | p-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p3 |
| Noble-gas notation | [Ne] 3s2 3p3 |
| Electrons per shell | 2, 8, 5 |
| Valence electrons | 5 |
Bohr model and shells
Phosphorus has 15 electrons in 3 shells: 2, 8, 5. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 317.3 K (44.2 °C) |
|---|---|
| Density | 1.823 g/cm³ |
| Electronegativity (Pauling) | 2.19 |
| Electron affinity | 72.037 kJ/mol |
| Ionization energies | 1011.8, 1907, 2914.1 kJ/mol (1st, 2nd, 3rd) |
| Molar heat capacity | 23.824 J/(mol·K) |
| Discovered by | Hennig Brand |
Use the atomic mass in the molar mass calculator for any formula containing P.
Position in the periodic table
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Molecules with phosphorus
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Frequently asked questions
What is the atomic mass of phosphorus?
The atomic mass of phosphorus is 30.974 u, so one mole of phosphorus atoms weighs 30.974 g.
What is the electron configuration of phosphorus?
Phosphorus has 15 electrons: 1s² 2s² 2p⁶ 3s² 3p³, or [Ne] 3s² 3p³ in noble-gas notation. Electrons per shell: 2, 8, 5.
How many valence electrons does phosphorus have?
Phosphorus has 5 valence electrons (group 15).
Is phosphorus a metal?
No. Phosphorus is a nonmetal (reactive nonmetal).
Where is phosphorus on the periodic table?
Phosphorus is in group 15 (pnictogens), period 3, in the p-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.