Phosphorus (P)
Reactive nonmetal · p-block · period 3 · group 15
White form is waxy and glows in the dark; red form is a dull powder.
Phosphorus (symbol P) is chemical element number 15, a reactive nonmetal in group 15, period 3 of the periodic table. Its standard atomic weight is 30.974 and its electron configuration is [Ne] 3s2 3p3. At room temperature it is a solid. The first element discovered by a known person — Brand distilled it from urine.
Properties
| Atomic number | 15 |
|---|---|
| Atomic mass | 30.974 |
| Category | Reactive nonmetal |
| Block | p-block |
| Group · Period | 15 · 3 |
| Electron configuration | [Ne] 3s2 3p3 |
| Electrons per shell | 2, 8, 5 |
| State at 25 °C | solid |
| Melting point | 317.3 K |
| Boiling point | 553.65 K |
| Density | 1.823 g/cm³ |
| Electronegativity (Pauling) | 2.19 |
| Radioactive | No |
| Origin | primordial |
| Discovered | 1669 · Hennig Brand |
Key facts about Phosphorus
- The first element discovered by a known person — Brand distilled it from urine.
- White phosphorus ignites spontaneously in air and is stored under water.
- Its faint glow in air is the original meaning of 'phosphorescence'.
- Part of DNA's backbone and of ATP, the cell's energy currency.
What Phosphorus is used for
Fertilisers, match heads, flame retardants, food additives, steel production.
Where it sits in the periodic table
Phosphorus is in group 15, period 3, of the p-block. Its electron configuration [Ne] 3s2 3p3 means its outermost shell holds 5 electrons, which is what places it here and explains much of its chemistry. See Phosphorus on the interactive table →
Phosphorus — frequently asked questions
What is Phosphorus used for?
Fertilisers, match heads, flame retardants, food additives, steel production.
Is Phosphorus radioactive?
No. Phosphorus has at least one stable isotope and is not radioactive.
What is the electron configuration of Phosphorus?
Phosphorus has the electron configuration [Ne] 3s2 3p3, which is 2, 8, 5 electrons per shell.
What group and period is Phosphorus in?
Phosphorus is in group 15, period 3, in the p-block. Its outer shell holds 5 electrons.
Who discovered Phosphorus?
Phosphorus was discovered in 1669 by Hennig Brand.