Phosphorus (P)
Phosphorus is element 15, a nonmetal in group 15, period 3. A neutral atom has 15 protons, 16 neutrons and 15 electrons, 5 of them valence electrons.
Nonmetal- Atomic number
- 15
- Atomic mass
- 30.974 u
- Valence electrons
- 5
- Protons · neutrons
- 15 · 16
- Electrons per shell
- 2, 8, 5
- At room temperature
- solid
Bohr model of phosphorus
The Bohr model draws phosphorus as a nucleus of 15 protons and 16 neutrons, with its 15 electrons on 3 circular shells: 2 in shell 1, 8 in shell 2, 5 in shell 3. Press Build the atom to watch the shells fill from the inside out. The outer ring (the M shell) is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of phosphorus
1s² 2s² 2p⁶ 3s² 3p³
Short form (noble gas notation): [Ne] 3s² 3p³. The [Ne] stands for the electrons of neon, the noble gas before it.
How many valence electrons does phosphorus have?
Phosphorus has 5 valence electrons.
Phosphorus is in group 15, and for groups 13–18 you subtract 10 from the group number: 15 − 10 = 5. It tends to gain 3 electrons to complete an octet, forming a −3 ion.
Protons, neutrons and electrons
| Protons | 15 | equal to the atomic number |
|---|---|---|
| Electrons | 15 | equal to the protons in a neutral atom |
| Neutrons | 16 | mass number 31 − 15 protons |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Phosphorus properties
| Symbol | P |
|---|---|
| Category | Nonmetal |
| Group · period · block | 15 · 3 · p |
| Atomic mass | 30.974 u |
| State at 25 °C | solid |
| Melting point | 317.3 K (44.2 °C, 111 °F) |
| Boiling point | 553.6 K (281 °C, 537 °F) |
| Density | 1.82 g/cm³ |
| Electronegativity (Pauling) | 2.19 |
| Atomic radius | 180 pm |
| First ionization energy | 10.487 eV |
| Electron affinity | 0.746 eV |
| Oxidation states | +5, +3, −3 |
| Common ion charge | −3 |
| Discovered | 1669 by Hennig Brand |
Where phosphorus sits on the periodic table
Group 15: Nitrogen, Arsenic, Antimony, Bismuth, Moscovium.
Questions about phosphorus
How many valence electrons does phosphorus have?
Phosphorus has 5 valence electrons.
How many protons, neutrons and electrons does phosphorus have?
A neutral phosphorus atom has 15 protons and 15 electrons. Its most common form has about 16 neutrons (mass number 31 − 15 protons).
What is the electron configuration of phosphorus?
1s² 2s² 2p⁶ 3s² 3p³, written in short form as [Ne] 3s² 3p³.
What does the Bohr model of phosphorus look like?
A nucleus of 15 protons and 16 neutrons, circled by 3 electron shells holding 2, 8, 5 electrons.
What is the atomic number of phosphorus?
15. The atomic number is the number of protons in the nucleus, and it is what makes an atom phosphorus.