Phosphorus Atomic Number

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Phosphorus is a non-metal with diverse biological and industrial significance. It was discovered in 1669 by Hennig Brand and has two allotropic forms and eighteen isotopes.

  • The stable isotope of phosphorous has an atomic number (Z) of 15, meaning that it has a nuclear charge of +15, and therefore, 15 protons (and 15 electrons). It also means that there are 16 neutrons in an atom of P-31. The mass number (A) of P-31 is the sum of the protons and neutrons. Follow up Emmie appears to be out to lunch.
  • Phosphorus (atomic number 15, symbol P) is a non-metal with a monoclinic structure and 3 main allotropes - black, red, and white. It has 3 oxidation states - 5, 4, 3 and is a multivalent non-mental. The element occurs in the form of phosphates, as organophosphates, and in minerals.

Discovery and History

Atomic Data for Phosphorus (P) Atomic Number = 15 Atomic Weight = 30.973762 Reference E95: Isotope: Mass: Abundance: Spin: Mag Moment: 31 P: 30.973762: 100%: 1/2 +1.13160: P I Ground State 1s 2 2s 2 2p 6 3s 2 3p 3 4 S° 3 / 2 Ionization energy 84580.83 cm-1 (10.48669 eV) Ref. MZM85 P II Ground State 1s 2 2s 2 2p 6 3s 2 3p 2 3 P 0.

The discovery of phosphorus as a novel element was carried out by in Hennig Brand in 1669 by evaporating urine. He obtained a white material that burned brilliantly and emitted a glow in the dark when exposed to oxygen [1]. Antoine Lavoisier identified phosphorus as a separate element in 1777. The name phosphorus also has an interesting origin, as Phosphorus is the name of planet Venus in Ancient Greece language and it means “carrier of light” or “light-bringer”. Commercial scale production of phosphorus was started by Brand and later many scientists, including Robert Boyle, used the same method of phosphorus production developed by Brand. In 1680, Boyle introduced the use of phosphorus to ignite wooden splints with tips of sulfur, and these later were developed into matches [2]. Phosphorus was initially used on a wide scale to make poisons, explosives and nerve agents and due to its toxic and lethal properties, it was commonly named as the “devil’s element”. Gottlieb Gahn and Carl Wilhelm (1796) were the first to discover the presence of phosphorus, in the form of calcium phosphate, in the bones. Until 1840s, one of the major sources of phosphorus has been ashes of bones, and until 1840s. Later in 1850s, the presence of phosphate in rocks on the form of calcium phosphate was discovered and the phosphorus production switched form bones to rocks.


Periodic Table ClassificationGroup 15
Period 3
State at 20CSolid
ColorColourless, waxy white, yellow, scarlet, red, violet, black
Electron Configuration[Ne] 3s2 3p3
Electron Number15
Proton Number15
Electron Shell2, 8, 5
Density1.82 at 20°C
Atomic number15
Atomic Mass30.97 g.mol -1
Electronegativity according to Pauling2.19


Phosphorus does not exist in free or elemental state in nature. It forms various compounds and is present in large variety of minerals. The most common source of phosphorus is calcium phosphate that is present in rocks. Phosphorus is an element of great biological value. It is the 6th most abundant element in the living systems. The largest natural reserves of phosphorus are present in Arab region. Other countries or regions that are significant producers of phosphorus include Russia, China, Florida and Morocco [3]. The annual production of elemental phosphorus is around 1000,000 tons.

Physical Characteristics

White phosphorus is yellowish white solid, that has a waxy texture. Phosphorus undergoes spontaneous ignition in air and forms pentoxide (P4O10). There are two allotropic forms of phosphorus, red and black, that differ in physical and chemical properties. Red phosphorus (which is formed by heating of white phosphorus at high temperature) ignites on friction. White phosphorus is a highly toxic substance., while red phosphorus is non-toxic [4]. Phosphorus is water insoluble. Black phosphorus is also termed as violet phosphorus and is the least reactive allotrope of phosphorus. It resembles graphite in appearance and structure.

Chemical Characteristics

White phosphorus is very reactive element. In the presence of oxygen, white phosphorus emits a light green glow, termed as chemiluminescence (glow caused by cold chemical reaction) [5]. The most abundant compounds of phosphorus contain the tetrahedral anion of phosphate (PO43-). There is a vast variety of phosphorus compounds including oxoacids (phosphoric acid), sulfides, nitrides (phosphorus nitride halogens (F2PN, Cl2PN), and phosphides (reaction of metals with red phosphorus). Phosphine (PH3) is a toxic compound with pungent smell, is structural analogue of ammonia. Diphosphine (P2H4), is an analogue of hydrazine and is highly flammable.

Uses and Significance

  • The largest use of phosphorus is in the production of fertilizers. It is an essential nutrient for the growth of plants.
  • Phosphorus is used in making of safety matches, and various ammunitions, such as incendiary shells and hand grenades etc.
  • Phosphorus is used in the manufacturing of bronze and steel.
  • It is used in making LEDs (light-emitting diodes).
  • Phosphorus is used in making detergents, that functions to remove water hardness and improve the efficiency of detergent.
  • It is used in synthesis of nerve agents.
  • It is used as active ingredient in various pesticides.
  • Phosphoric acid is widely used in manufacturing of soft drinks, baking powder.
  • Various compounds of phosphate are used in processing of cheese and meat.

Health Hazards

Phosphorus in the form of phosphate is a vital compound for all living systems. The energy currency of cell, ATP (adenosine triphosphate) that regulates every process in the living cell, uses phosphate. Phosphorylation, that is the process of adding phosphate to various biological molecules, is an important regulatory mechanism in living organisms. Lipids in combination with phosphorus (phospholipids) are the primary building blocks of cell membrane. Phosphorus is present in the building blocks of RNA and DNA. A balanced diet includes a definitive everyday intake of phosphorus. About 0.7 kg of phosphorus is present in an average adult human being, mostly in teeth and bones and in soft tissues of the body. deficiency of phosphate in the body can lead to various physiological effects, including tissue weakness, neurological defects and lack of ATP. Increased intake of phosphate can cause hardening of tissues and organs and diarrhea.

Isotopes of Phosphorus

There are twenty-three isotopes of phosphorus, that range in atomic numbers from 26 to 43. Natural phosphorus constitutes only one stable isotope, phosphorus-31 [6].


[1]. Beatty, Richard (2000). Phosphorus. Marshall Cavendish. p. 7. ISBN0-7614-0946-7.

[2]. Peter Baccini; Paul H. Brunner. Metabolism of the Anthroposphere. MIT Press, 2012. p. 288. ISBN0262300540.

[3]. Philpott, Tom (March–April 2013). “You Need Phosphorus to Live—and We’re Running Out”. Mother Jones.fwhi

[4]. Abundance.

Phosphorus Atomic Number

[5]. Michael A. Sommers. Phosphorus. The Rosen Publishing Group, 2007. p. 25. ISBN1404219609.

Other Periodic Table Elements

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Phosphorus-32, 32P
Namesphosphorus-32, P-32
Nuclide data
Natural abundancetrace
Half-life14.268 days
Decay products32S
Isotope mass31.973907274 u
Excess energy24305 keV
Decay modes
Decay modeDecay energy (MeV)
Beta emission1.709
Isotopes of phosphorus
Complete table of nuclides

Phosphorus-32 (32P) is a radioactive isotope of phosphorus. The nucleus of phosphorus-32 contains 15 protons and 17 neutrons, one more neutron than the most common isotope of phosphorus, phosphorus-31. Phosphorus-32 only exists in small quantities on Earth as it has a short half-life of 14 days and so decays rapidly.

Phosphorus is found in many organic molecules and so phosphorus-32 has many applications in medicine, biochemistry, and molecular biology where it can be used to trace phosphorylated molecules (for example, in elucidating metabolic pathways) and radioactively label DNA.


Phosphorus has a short half-life of 14.268 days and decays into sulfur-32 by beta decay[1] as shown in this nuclear equation:


1.709 MeV of energy is released during the decay.[2] The kinetic energy of the electron varies with an average of approximately 0.5 MeV and the remainder of the energy is carried by the nearly undetectable electron antineutrino. In comparison to other beta radiation-emitting nuclides the electron is moderately energetic. It is blocked by around 1 m of air or 5 mm of acrylic glass.

The sulfur-32 nucleus produced is in the ground state so there is no additional gamma ray emission.


Phosphorus-32 has important uses in medicine, biochemistry and molecular biology. It only exists naturally on earth in very small amounts and its short half-life means useful quantities have to be produced synthetically. Phosphorus-32 can be generated synthetically by irradiation of sulfur-32 with moderately fast neutrons as shown in this nuclear equation:



Phosphorus 30 Atomic Number

The sulfur-32 nucleus captures the neutron and emits a proton, reducing the atomic number by one while maintaining the mass number of 32.

This reaction has also been used to determine the yield of nuclear weapons.[3][4]


Phosphorus is abundant in biological systems and, as a radioactive isotope is almost chemically identical with stable isotopes of the same element, phosphorus-32 can be used to label biological molecules. The beta radiation emitted by the phosphorus-32 is sufficiently penetrating to be detected outside the organism or tissue which is being analysed

Nuclear medicine[edit]

Phosphorus Atomic Number

Many radioisotopes are used as tracers in nuclear medicine, including iodine-131, phosphorus-32, and technetium-99m. Phosphorus-32 is of particular use in the identification of malignant tumours because cancerous cells have a tendency to accumulate more phosphate than normal cells.[5] The location of the phosphorus-32 can be traced from outside the body to identify the location of potentially malignant tumors.

The radiation emitted by phosphorus-32 can be used for therapeutic as well as diagnostic purposes. The use of 32P-chromic phosphate has been explored as a possible chemotherapy agent to treat disseminated ovarian cancer.[6] In this situation, it is the long-term toxic effects of beta radiation from phosphorus-32 accumulating in the cancerous cells which has the therapeutic effect. Phosphorus-32 is widely used for cancer detection and treatment, especially in eyes and skin cancer.

Biochemistry and molecular biology[edit]

The metabolic pathways of organisms extensively use phosphorus in the generation of different biomolecules within the cell. Phosphorus-32 finds use for analysing metabolic pathways in pulse chase experiments where a culture of cells is treated for a short time with a phosphorus-32-containing substrate. The sequence of chemical changes which happen to the substrate can then be traced by detecting which molecules contain the phosphorus-32 at multiple time points following the initial treatment.

DNA contains a large quantity of phosphorus in the phosphodiester linkages between bases in the oligonucleotide chain. DNA can therefore be tracked by replacing the phosphorus with phosphorus-32. This technique is extensively used in Southern blot analysis of DNA samples. In this case a phosphorus-32-containing DNA probe hybridises to its complementary sequence where it appears in a gel. Its location can then be detected by photographic film.

Phosphorus Atomic Weight Test

Plant sciences[edit]

Phosphorus-32 is used in plant sciences for tracking a plant's uptake of fertiliser from the roots to the leaves. The phosphorus-32-labelled fertiliser is given to the plant hydroponically or via water in the soil and the usage of the phosphorus can be mapped from the emitted beta radiation. The information gathered by mapping the fertiliser uptake show how the plant takes up and uses the phosphorus from fertiliser.[7]


Phosphorus-33 (atomic Number 15) Contains

The high energy of emitted beta particles and the low half-life of phosphorus-32 make it potentially harmful; Its molar activity is 338 TBq/mmol (9131 Ci/mmol). Typical safety precautions when working with phosphorus-32 include wearing a personal dosimeter to monitor exposure and an acrylic or perspex radiation shield to protect the body. Dense shielding, such as lead, is less effective due to the high-energy bremsstrahlung produced by the interaction of the beta particle and the shielding. Because the beta radiation from phosphorus-32 is blocked by around 1 m of air it is also advisable to wear dosimeters on the parts of the body, for example the fingers, which come into close contact with the phosphorus-32-containing sample.

How Many Protons Are In Phosphorus


  1. ^Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). 'The NUBASE2016 evaluation of nuclear properties'(PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
  2. ^ 2006-07-05 at the Wayback Machine
  3. ^Kerr, George D.; Young, Robert W.; Cullings, Harry M.; Christy, Robert F. (2005). 'Bomb Parameters'(PDF). In Robert W. Young, George D. Kerr (ed.). Reassessment of the Atomic Bomb Radiation Dosimetry for Hiroshima and Nagasaki – Dosimetry System 2002. The Radiation Effects Research Foundation. pp. 42–43.
  4. ^Malik, John (September 1985). 'The Yields of the Hiroshima and Nagasaki Explosions'(PDF). Los Alamos National Laboratory. Retrieved March 9, 2014.
  5. ^'radioactivity'. Encyclopædia Britannica. Retrieved 2016-02-13.
  6. ^Pattillo, Roland A.; Collier, B. David; Abdel-Dayem, Hussein; Ozker, Kutlan; Wilson, Charles; Ruckert, Anna C. F.; Hamilton, Karen (1995-01-01). 'Phosphorus-32-Chromic Phosphate for Ovarian Cancer: I. Fractionated Low-Dose Intraperitoneal Treatments in Conjunction with Platinum Analog Chemotherapy'. Journal of Nuclear Medicine. 36 (1): 29–36. ISSN0161-5505. PMID7799078.
  7. ^Singh, B., Singh, J., & Kaur, A. (2013). Applications of Radioisotopes in Agriculture. International Journal of Biotechnology and Bioengineering Research,4(3), 167-174.

Phosphorus Atomic Number Electronic Configuration

External links[edit]

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