Phosphorus (P): Bohr Model, Protons, Neutrons & Electrons
Phosphorus is element number 15, a nonmetal in group 15, period 3. Its atom has 15 protons, 16 neutrons and 15 electrons arranged in 3 shells: 2, 8, 5.
Protons, neutrons and electrons in phosphorus
The atomic number of phosphorus is 15, so every phosphorus atom has 15 protons. A neutral atom has the same number of electrons, 15. The number of neutrons depends on the isotope: neutrons = mass number − atomic number. For phosphorus-31, that is 31 − 15 = 16 neutrons.
How to draw the Bohr model of phosphorus
- Draw the nucleus and write 15 p⁺ and 16 n⁰ inside it.
- Draw the first shell and put 2 electrons on it (the first shell holds at most 2).
- Draw the second shell and put 8 electrons on it.
- Draw the third shell and put 5 electrons on it.
- Check: 2 + 8 + 5 = 15 electrons, the same as the number of protons.
Electron configuration
The electron configuration of phosphorus is [Ne] 3s² 3p³. Its 5 outer electrons decide how it reacts: it tends to gain 3 more, forming P³⁻ ions.
Key facts about phosphorus
| Symbol | P |
|---|---|
| Atomic number | 15 |
| Relative atomic mass | 30.974 |
| Group · period · block | group 15 · period 3 · p-block |
| Type | Nonmetal |
| State at 25 °C | solid |
| Electron shells | 2, 8, 5 |
| Electron configuration | [Ne] 3s² 3p³ |
| Valence electrons | 5 |
| Common ion | P³⁻ |
| Electronegativity (Pauling) | 2.19 |
| First ionisation energy | 10.49 eV (1012 kJ/mol) |
| Atomic radius (empirical) | 100 pm |
Where phosphorus sits on the periodic table
Frequently asked questions
How many protons, neutrons and electrons does phosphorus have?
Phosphorus has 15 protons and 15 electrons (atomic number 15). Its most common isotope, phosphorus-31, has 31 − 15 = 16 neutrons.
What is the electron configuration of phosphorus?
[Ne] 3s² 3p³. In shells that is 2, 8, 5.
How many valence electrons does phosphorus have?
5. Phosphorus is in group 15, and its outer shell holds 5 electrons.
Where is phosphorus on the periodic table?
In group 15, period 3, in the p-block. It is a nonmetal.
