Phosphorus (P): electron configuration, atomic mass and facts
Phosphorus (P) is element 15 of the periodic table, a reactive nonmetal in period 3, group 15. Its electron configuration is [Ne] 3s2 3p3, with electrons arranged in shells 2, 8, 5, and its standard atomic weight is 30.974 u.
💡 White phosphorus glows in the dark and catches fire in air.
▶ Watch Phosphorus’s electrons orbit in the interactive periodic tablePhosphorus at a glance
| Symbol | P |
|---|---|
| Atomic number | 15 |
| Atomic mass | 30.974 u |
| Category | Reactive nonmetal |
| Group | 15 |
| Period | 3 |
| Block | p-block |
| Electron configuration | 1s2 2s2 2p6 3s2 3p3 |
| Noble-gas shorthand | [Ne] 3s2 3p3 |
| Electrons per shell | 2, 8, 5 |
| Outer-shell electrons | 5 |
| Electronegativity (Pauling) | 2.19 |
| State at 20 °C | solid |
Where is Phosphorus on the periodic table?
Phosphorus is in period 3, group 15, in the p-block. The period number matches its 3 electron shells, and the block names the subshell its last electrons fill. In the same group, Nitrogen sits directly above it and Arsenic sits directly below it. Elements in one group have the same number of outer-shell electrons (5 here), which is why they react in similar ways.
How to work out the electron configuration of Phosphorus
Put 15 electrons into subshells in order of rising energy, filling each before starting the next: 1s² (2), 2s² (4), 2p⁶ (10), 3s² (12), 3p³ (15). In shorthand, [Ne] stands for the 10 electrons of neon, giving [Ne] 3s² 3p³.
How electronegative is Phosphorus?
Phosphorus has a Pauling electronegativity of 2.19, ranking 24 of the 100 elements with a known value (fluorine is highest at 3.98). That is in the middle of the range.
Phosphorus in the virtual lab
Faradium’s chemistry workbench includes these chemicals that contain phosphorus: Red phosphorus. Open the Chemistry Lab to experiment with them.
Frequently asked questions
What is the electron configuration of Phosphorus?
The electron configuration of Phosphorus (P) is 1s2 2s2 2p6 3s2 3p3. In noble-gas shorthand it is written [Ne] 3s2 3p3.
How many electrons does Phosphorus have in each shell?
Phosphorus has 15 electrons arranged in shells as 2, 8, 5. It has 5 electrons in its outer shell.
What is the atomic mass of Phosphorus?
The standard atomic weight of Phosphorus is 30.974 u, so one mole of Phosphorus atoms has a mass of about 30.974 g.
Is Phosphorus a metal?
No. Phosphorus is a reactive nonmetal.
Explore nearby elements
More reactive nonmetals: Hydrogen, Carbon, Nitrogen, Oxygen, Sulfur, Selenium. See all elements on the periodic table.