Phosphorus is a chemical element that has an atomic number (Z) 15.  It is represented by the symbol 'P'. Its atomic weight is 30.973. It exists in two major elemental forms, red phosphorus and white phosphorus. It is very reactive in pure form that's why it is not existing in free form. Pure phosphorus is white in colour but can be found in yellow, red, violet, black metallic colours depending on the compound and impurity. In periodic table, it could be found in the 3rd period and group 15 (pnictogens). It is a p-block element and its electronic configuration is [Ne] 3s2 3p3. Its electronegativity is 2.19 (Pauling scale). The oxidation state is varied from −3, −2, −1, 0, +1, +2, +3, +4, +5 depending on the bonding atom or molecule. It is solid at standard temperature and pressure. Its melting point (white) is 317.3 K ?(44.15 °C, ?111.5 °F) and boiling point is  553.7 K ?(280.5 °C, ?536.9 °F).

There are 23 isotopes of phosphorus, only one is stable and the remaining are radioisotopes. Phosphorus-31 is a naturally occurring stable isotope and has an abundance of 100%. It was discovered by a German alchemist Hennig Brand in 1669. But it was recognized by Antoine Lavoisier as an element. Phosphorus is an essential element for life. It is part of DNA, RNA and ATPs etc. It is a very reactive element and does not found free. It is found in different minerals and in phosphorus compounds.

 

How many valence electrons does phosphorus have?

The electronic configuration of Phosphorus is 1s2, 2s2, 2p6, 3s2, 3p3. Phosphorus has 5 valence electrons, two are in the 3s orbital and three are in the 3p-orbitals.

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What is phosphorus used for?

Phosphorus has a wide range of uses. In elemental form, it is highly reactive and can be found in different compounds. some of them are the following.

sodium tripolyphosphate is used in detergents as a water softening agent.

It is an essential nutrient for plants. It is used in fertilizer (phosphoric(V) acid).

It is used in the manufacturing of additives and pesticides.

It is used in match production.

White phosphorus is used in smoking bomb and smoking grenade.

Calcium dihydrogen phosphate is used as a leavening agent in the food industry.

Phosphorus-32 and phosphorus-33 are used as tracers in biological experiments.