Element 15 · Reactive nonmetal
Phosphorus (P) — Element 15
Greek phosphoros — light-bearer
Phosphorus (P) is a reactive nonmetal in Period 3, Group 15 of the periodic table with atomic number 15, standard atomic weight 30.974 u, and ground-state electron configuration [Ne] 3s² 3p³. At standard temperature and pressure it is classified as a solid with 5 valence electrons and common oxidation states -3, +3, +5.
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What are the atomic properties and physical constants of Phosphorus?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 15
- Standard atomic mass
- 30.974 u
- Chemical family
- Reactive nonmetal
- Ground-state configuration
- [Ne] 3s² 3p³
- Electrons per shell
- 2, 8, 5
- Valence electrons
- 5
- Common ion charges / oxidation states
- -3, +3, +5
- Phase at STP
- Solid
- Pauling electronegativity
- 2.19 Pauling
- First ionization energy
- 1,012 kJ/mol
- Atomic radius
- 98 pm
- Melting point
- 44 °C
- Boiling point
- 281 °C
- Discovery year
- 1669
- Table coordinate
- Period 3, Group 15
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Phosphorus’s shells?
A neutral Phosphorus atom contains 15 electrons distributed across 3 occupied principal energy shells ([Ne] 3s² 3p³). The table below compares Phosphorus’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in P | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 5 e⁻ | 18 e⁻ |
Frequently Asked Questions about Phosphorus (P)
What is the atomic mass and atomic number of Phosphorus (P)?
Phosphorus (P) has atomic number Z = 15 (15 protons in its nucleus) and an IUPAC standard atomic weight of 30.974 u. It sits in Period 3, Group 15 and is classified as a reactive nonmetal.
What is the ground-state electron configuration of Phosphorus?
The neutral ground-state electron configuration of Phosphorus (Z = 15) is [Ne] 3s² 3p³. Across its 3 occupied principal shells (n = 1 to n = 3), the electrons per shell are 2, 8, 5, with 5 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Phosphorus?
Phosphorus commonly forms -3, +3, +5 oxidation states or ion charges in compounds. Its Pauling electronegativity is 2.19 and its first ionization energy is 1,012 kJ/mol.
When was Phosphorus discovered and what is it used for?
Phosphorus was discovered in 1669 (Greek phosphoros — light-bearer). Fertilizer, DNA, matches
How does Phosphorus compare to neighboring elements?
Other reactive nonmetal elements: