Phosphorus Element Properties
Complete reference for Phosphorus (P, element 15): atomic data, electron configuration with interactive orbital diagram, isotopes, physical constants, and a temperature unit toggle.
Phosphorus
Nonmetal — Period 3, Group 15
Atomic Identity
Electron Configuration
Half-filled 3p subshell — quartet ground state (⁴S°₃/₂)
Physical Properties
Values shown for white phosphorus (P₄) unless noted. Red phosphorus sublimes at ~416 °C; black phosphorus melts at ~610 °C.
Key Isotopes of Phosphorus
| Isotope | Symbol | Protons | Neutrons | Mass (u) | Natural Abundance | Notes |
|---|---|---|---|---|---|---|
| Phosphorus-30 | ³⁰P | 15 | 15 | 29.97832 | Radioactive |
Unstable
β⁺ decay, t½ = 2.498 min
|
| Phosphorus-31 | ³¹P | 15 | 16 | 30.97376 | 100% |
Stable
Only stable isotope (monoisotopic)
|
| Phosphorus-32 | ³²P | 15 | 17 | 31.97391 | Radioactive |
Unstable
β⁻ decay, t½ = 14.268 days; radiotracer
|
| Phosphorus-33 | ³³P | 15 | 18 | 32.97172 | Radioactive |
Unstable
β⁻ decay, t½ = 25.35 days; low-energy tracer
|
| Phosphorus-34 | ³⁴P | 15 | 19 | 33.97364 | Radioactive |
Unstable
β⁻ decay, t½ = 12.43 s
|
Phosphorus-32 (³²P) is the workhorse radiotracer of molecular biology — used for labeling DNA and RNA probes, kinase assays, and gel electrophoresis autoradiography. Phosphorus-33 (³³P) gives sharper autoradiographic bands due to its lower beta energy.
Chemical Properties
Atomic Properties
Phosphorus Allotropes
Toxic, pyrophoric, glows in air (chemiluminescence). Ignites spontaneously at ~34 °C. Soluble in carbon disulfide.
Stable, non-toxic powder. Used in safety matches (strike plates) and flame retardants. Insoluble in common solvents.
Most thermodynamically stable form. Semiconductor; 2D monolayers (phosphorene) have electronic properties analogous to graphene.
Known as Hittorf's phosphorus. Produced by slow crystallization from molten lead at ~530 °C. Rarely encountered outside research.
Key Facts About Phosphorus
Essential for DNA and ATP
Phosphate groups (PO₄³⁻) form the backbone of every DNA and RNA strand in all known life. Adenosine triphosphate (ATP) carries cellular energy via high-energy P–O–P anhydride bonds. Without phosphorus, life as we know it cannot exist.
Agricultural Fertilizers
Phosphorus (as phosphate) is one of the three primary macronutrients (NPK) in fertilizer. It drives root development, flowering, and seed formation. Global agriculture would be impossible at current scale without mined phosphate rock — a finite, non-renewable resource.
Phosphoric Acid (H₃PO₄)
The most commercially important phosphorus compound. Produced by reacting phosphate rock with sulfuric acid. Used to manufacture fertilizers (superphosphate), as a food additive (E338, for acidity in colas), in rust removal, and in the semiconductor industry for silicon etching.
Discovery in 1669
Phosphorus was the first element to be chemically isolated (by a non-accidental process). Alchemist Hennig Brand of Hamburg discovered it by evaporating and heating large quantities of urine, observing a glowing residue — hence the name from Greek "phosphoros" (light-bearer).
Flame Retardants
Organophosphate and phosphorus-halogen compounds are key flame retardants used in electronics, textiles, and construction materials. They work by interfering with combustion chain reactions in the gas phase (radical scavenging) and by promoting char formation (condensed phase action).
Phosphorus-32 in Research
The radioactive isotope ³²P (t½ = 14.27 days, Emax = 1.71 MeV) is an essential tool in molecular biology. It labels nucleic acid probes for Southern and Northern blotting, measures kinase activity in phosphorylation assays, and maps DNA-protein interactions via DNase I footprinting.
Summary
Complete reference for Phosphorus (P, element 15): atomic data, electron configuration with interactive orbital diagram, isotopes, physical constants, and a temperature unit toggle.
How it works
- Browse the atomic identity section for symbol, atomic number, and standard atomic weight.
- Check the electron configuration panel for orbital notation and the interactive shell diagram.
- Toggle the temperature unit (°C / °F / K) on the physical properties card to convert melting and boiling points.
- Review the isotopes table for key phosphorus isotopes including the radioactive tracer P-32.
- Consult the chemical properties panel for electronegativity, ionization energies, and oxidation states.
- Explore the key facts section for biological roles, industrial uses, and allotrope details.
Use cases
- Look up phosphorus constants for chemistry homework or exams.
- Verify atomic data when writing lab reports or research papers.
- Reference isotope data for P-32 radiotracer experiments in biochemistry.
- Check physical properties of white and red phosphorus for safety data sheets.
- Teach or learn phosphorus chemistry and its role in biological molecules.
- Confirm electron configuration before writing molecular orbital or Lewis structure diagrams.
- Quick-reference oxidation states for inorganic or analytical chemistry work.
- Review electronegativity and ionization energy for spectroscopy or computational chemistry.