Phosphorus is an essential mineral for plant growth. It’s also required for the growth of teeth and bones. It helps the body produce protein, which is necessary for cell and tissue growth, maintenance, and repair. Phosphorus is abundant in milk, milk products, grains, vegetables, and fruits.

By adding phosphate-rich manure to the soil and using phosphate-containing detergents, humans have drastically altered the natural phosphate supply. Phosphates are also found in a variety of foods, including cheese, sausages, and hams. Too much phosphate in your body can lead to health issues like renal damage and osteoporosis. Phosphate shortages are also a possibility. They are brought on by long-term use of the medication. Phosphate deficiency can be harmful to your health.

In this article, let’s learn the importance of phosphorus and its properties in detail. Continue reading to know more.

What is Phosphorus?

Phosphorus is a chemical element with the symbol \({\rm{P}}\) and atomic number \(15\). It is a non-metal that belongs to the 15th group of the periodic table and is placed just below the nitrogen.

It was discovered by Hennig Brand in \(1669\). Phosphorus exists as \({{\rm{P}}_{\rm{4}}}\) in elemental state and exists in many allotropic forms. Phosphorus is the \({\rm{1}}{{\rm{2}}^{{\rm{th}}}}\) most abundant element on the earth’s crust. Phosphorus does not occur in nature because of its high reactivity. It is found in a combined state and is widely distributed in nature. Phosphorus is an essential constituent of the bones, blood, teeth, and nervous tissues of animals. It is also present in plants mainly in the seed proteins, egg and milk. Biomolecules such as DNA, RNA, ADP, and ATP contain phosphorus. In the earth’s crust, it mainly occurs as phosphate minerals.

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The important phosphorus minerals are:

i. Phosphorite \({\rm{C}}{{\rm{a}}_{\rm{3}}}{\left( {{\rm{P}}{{\rm{O}}_{\rm{4}}}} \right)_{\rm{2}}}\)

ii. Fluorapatite \({\rm{3C}}{{\rm{a}}_{\rm{3}}}{\left( {{\rm{P}}{{\rm{O}}_{\rm{4}}}} \right)_{\rm{2}}}{\rm{Ca}}{{\rm{F}}_{\rm{2}}}\)

iii. Chloropatite \({\rm{3C}}{{\rm{a}}_{\rm{3}}}{\left( {{\rm{P}}{{\rm{O}}_{\rm{4}}}} \right)_{\rm{2}}}{\rm{CaC}}{{\rm{l}}_{\rm{2}}}\)

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Phosphorus Structure

Phosphorus exists as a discrete tetratomic molecule \(\left( {{{\rm{P}}_{\rm{4}}}} \right){\rm{.}}\) In this molecule, four phosphorus atoms are held together by strong single \({\rm{P—P}}\) covalent bonds in a tetrahedral manner. This type of bonding makes \({{\rm{P}}_4}.\) molecule to be very stable.

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Molecular Mass of Phosphorus

Molecular mass is the mass of a molecule that is equal to the sum of the masses of all the atoms contained in the molecule. We know that phosphorus forms a tetratomic molecule. Hence, the molecular mass of phosphorus is \(123.88 u.\)

This can be calculated as follows:

There are \(4\) phosphorus atoms per molecule.

The atomic mass of phosphorus is \({\rm{30}}{\rm{.97 u}}{\rm{.}}\)

Therefore, the molar mass of phosphorus is \({\rm{ = 4 \times Atomic\;mass\;of\;Phosphorus = 4 \times 30}}{\rm{.97 = 123}}{\rm{.88\;g}}{\rm{.}}\)

Allotropic Forms of Phosphorus

Phosphorus exists in many allotropic forms. Of these three main allotropic forms are :

i. White phosphorus: It is a common variety of phosphorus. It is obtained when phosphate rock is heated with coke and sand in an electric furnace at \({\rm{1773}}\,{\rm{K}}{\rm{.}}\)

Structure: It exists as \({{\rm{P}}_{\rm{4}}}\) units. The four \({\rm{s}}{{\rm{p}}^{\rm{3}}}\)-hybridized phosphorus atoms lie at the comers of a regular tetrahedron with \(\angle {\rm{PPP}}\,{\rm{ = }}\;{\rm{6}}{{\rm{0}}^{\rm{o}}}.\) Each phosphorus atom is linked to three other P-atoms by covalent bonds so that each p-atom completes its octet.

 

ii. Red phosphorus: It is obtained by heating white phosphorus in an inert atmosphere (out of contact of air) at \({\rm{573}}\,{\rm{K}}\) for several days.

Structure: The red phosphorus has a polyatomic structure. It is made up of a chain of \({{\rm{P}}_{\rm{4}}}\) tetrahedra that are linked together. Red phosphorus is less reactive than white phosphorus due to its polymeric structure.

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iii. Black phosphorus: Black phosphorus has two forms \({\rm{\alpha – }}\)black phosphorus and \({\rm{\beta – }}\) black phosphorus. \({\rm{\alpha – }}\)Black phosphorus is formed when red phosphorus is heated in a sealed tube at \({\rm{803}}\,{\rm{K}}{\rm{.}}\) \({\rm{\beta – }}\) phosphorus is prepared by heating white phosphorus at \({\rm{473}}\,{\rm{K}}\) under high pressure. It does not burn in the air up to \({\rm{673 K}}{\rm{.}}\)

Structure: It has a double-layered crystal lattice. Each layer is made up of zig-zag chains with \({\rm{P—P—P}}\) bond angles of \({\rm{9}}{{\rm{9}}^{\rm{o}}}\) and a \({\rm{P—P}}\) bond distance of \({\rm{218}}\,{\rm{pm}}{\rm{.}}\) It has a high density due to its highly polymeric nature.

Properties of Phosphorus

The properties of Phosphorus are given below:

Phosphorus Physical Properties

Property	Phosphorus
Symbol	\({\rm{P}}\)
Atomic number	\(15\)
Electronic configuration	\(\left[ {{\rm{Ne}}} \right]{\rm{3}}{{\rm{s}}^{\rm{2}}}{\rm{3}}{{\rm{p}}^{\rm{3}}}\)
Atomic mass	\({\rm{30}}{\rm{.97 u}}\)
Physical state	Vapourisable solid
Covalent radius \(\left( {{\rm{pm}}} \right)\)	\(110\)
Ionic radius \(\left( {{\rm{pm}}} \right)\)	\(212\,\left( {{{\rm{P}}^{ – 3}}} \right)\)
Density at \({\rm{298}}\,\,{\rm{K}}\,\,\left( {{\rm{g\;c}}{{\rm{m}}^{{\rm{ – 2}}}}} \right)\)	\(1.823\)
Melting point \(\left( {\rm{K}} \right)\)	\(317.1\) (White phosphorus)
Boiling point \(\left( {\rm{K}} \right)\)	\(553.5\) (White phosphorus)
Electronegativity	\(2.1\)
First ionisation enthalpy \(\left( {{\rm{kJ\;mo}}{{\rm{l}}^{{\rm{ – 1}}}}} \right)\)	\(1012\)
Second ionisation enthalpy \(\left( {{\rm{kJ\;mo}}{{\rm{l}}^{{\rm{ – 1}}}}} \right)\)	\(1903\)
Third ionisation enthalpy \(\left( {{\rm{kJ\;mo}}{{\rm{l}}^{{\rm{ – 1}}}}} \right)\)	\(2910\)
Abundance in earth’s crust \(\left( {{\rm{ppm}}} \right)\)	\(1120\)
Allotropy	White phosphorus, red phosphorus and black phosphorus

Phosphorus Chemical Properties

Action with air: The action of air on white phosphorus: It readily catches fire in the air and forms white fumes of \({{\rm{P}}_{\rm{4}}}{{\rm{O}}_{{\rm{10}}}}\)

\({{\rm{P}}_{\rm{4}}}\left( {\rm{s}} \right){\rm{ + 5}}{{\rm{O}}_{\rm{2}}}\left( {\rm{g}} \right) \to {{\rm{P}}_{\rm{4}}}{{\rm{O}}_{{\rm{10}}}}\left( {\rm{s}} \right)\)

The action of air on red phosphorus. Red phosphorus does not catch fire in the air. That is, it does not glow in the air under normal conditions.

The action of air on black phosphorus: It does not oxidize in air.

Reaction with acids: The action of acid with white phosphorus: White phosphorus is a weak reducing agent and reduces sulphuric acid to sulphur dioxide and nitric acid to nitric oxide, etc.

\({{\rm{P}}_{\rm{4}}}{\rm{ + \;10}}{{\rm{H}}_{\rm{2}}}{\rm{S}}{{\rm{O}}_{\rm{4}}} \to {\rm{10S}}{{\rm{O}}_{\rm{2}}}{\rm{ + \;4}}{{\rm{H}}_{\rm{3}}}{\rm{P}}{{\rm{O}}_{\rm{4}}}{\rm{ + \;4}}{{\rm{H}}_{\rm{2}}}{\rm{O}}\)

\({{\rm{P}}_{\rm{4}}}{\rm{ + 20HN}}{{\rm{O}}_{\rm{3}}}{\rm{\;}} \to {\rm{4}}{{\rm{H}}_{\rm{3}}}{\rm{P}}{{\rm{O}}_{\rm{4}}}{\rm{ + \;20N}}{{\rm{O}}_2}{\rm{ + \;4}}{{\rm{H}}_{\rm{2}}}{\rm{O}}\)

The action of acid with red phosphorus: Oxidising acids such as nitric acid oxidizes red phosphorus to phosphoric acid.

\({{\rm{P}}_{\rm{4}}}{\rm{ + 20HN}}{{\rm{O}}_{\rm{3}}}{\rm{\;}} \to {\rm{4}}{{\rm{H}}_{\rm{3}}}{\rm{P}}{{\rm{O}}_{\rm{4}}}{\rm{ + \;20N}}{{\rm{O}}_{\rm{2}}}{\rm{ + 4}}{{\rm{H}}_{\rm{2}}}{\rm{O}}\)

Phosphorus Reaction With Alkalies

The action of alkalies with white phosphorus: When white phosphorus is heated with caustic soda solution, phosphine gas is evolved which is a poisonous gas.

\({{\rm{P}}_{\rm{4}}}{\rm{ + 3NaOH + 3}}{{\rm{H}}_{\rm{2}}}{\rm{O}} \to {\rm{P}}{{\rm{H}}_{\rm{3}}}{\rm{+ Na}}{{\rm{H}}_{\rm{2}}}{\rm{P}}{{\rm{O}}_{\rm{2}}}\)

The action of alkalies with red phosphorus: Red phosphorus does not react with alkali solution under ordinary conditions. This property is made in separating red phosphorus from white phosphorus.

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Phosphorus Reaction With Halides

The reaction of white phosphorus with halogens. Phosphorus combines readily with the halogens forming halides. For example, it ignites spontaneously in chlorine forming tri and penta-chlorides.

\({{\rm{P}}_{\rm{4}}}{\rm{ + 6C}}{{\rm{l}}_{\rm{2}}} \to {\rm{4PC}}{{\rm{l}}_{\rm{3}}}\)

\({{\rm{P}}_{\rm{4}}}{\rm{ + \;10C}}{{\rm{l}}_{\rm{2}}} \to {\rm{4PC}}{{\rm{l}}_{\rm{5}}}\)

The reaction of red phosphorus with halogens. With halogens red phosphorus reacts only at high temperatures, forming tri and penta-halides.

Phosphorus Reaction With Metals

Reaction of white phosphorus with metals: Phosphorus combines with metals like \({\rm{Na, K, Mg, Ca, Ag, Cu,}}\) etc. and forms their respective phosphides.

For example,

\(12{\rm{Na}} + {{\rm{P}}_4} \to \mathop {4{\rm{N}}{{\rm{a}}_3}{\rm{P}}}\limits_{{\rm{Sodium}}\,{\rm{phosphide}}}\)

\(12{\rm{Ag}} + {{\rm{P}}_4} \to \mathop {4{\rm{A}}{{\rm{g}}_3}{\rm{P}}}\limits_{{\rm{Silver}}{\kern 1pt} {\rm{phosphide}}}\)

Reaction of red phosphorus with metals: It is less reactive than white phosphorus. Therefore, it reacts with metals only when heated and forms their respective salts.

For example,

Phosphorus Reaction With Sulphur

Reaction of white phosphorus with sulphur: White phosphorus reacts violently with sulphur to form a variety of sulphides, such as \({{\rm{P}}_{\rm{2}}}{{\rm{S}}_{\rm{3}}}{\rm{,\;}}{{\rm{P}}_{\rm{2}}}{{\rm{S}}_{\rm{5}}}{\rm{,\;}}{{\rm{P}}_{\rm{4}}}{{\rm{S}}_{\rm{3}}}{\rm{,\;}}{{\rm{P}}_{\rm{4}}}{{\rm{S}}_{\rm{7}}}{\rm{,\;etc}}{\rm{.}}\)

For example, \({\rm{8}}{{\rm{P}}_{\rm{4}}}{\rm{ + }}\;{\rm{3}}{{\rm{S}}_{\rm{8}}}\; \to 8{{\rm{P}}_{\rm{4}}}{{\rm{S}}_{\rm{3}}}\)

Reaction of red phosphorus with sulphur: It is less reactive than white phosphorus. Therefore, it reacts with sulphur only when heated and forms respective salt.
For example,

Uses of Phosphorus

1. Red phosphorus is largely used in the match industry for the manufacture of safety matches.
2. It is used in the manufacture of alloy. For example, phosphor bronze, an alloy of Phosphorus, Tin and Copper. Ferro phosphorus is used as a filter in high-density concrete and in radiation shields for nuclear reactors.
3. Yellow phosphorus is used in the manufacture of incendiary bombs, smoke screens and fireworks.
4. It is used in the manufacture of compounds like hypophosphites, phosphorus chlorides, phosphoric acid, etc. which find use in medicine and chemical industries.
5. White phosphorus is used in small amounts in rat poisons.
6. Certain compounds, such as phosphate, are utilized as fertilizer.

Summary

From this article, we can conclude that Phosphorus is the \({12^{th}}\)  most abundant element on the earth, and due to its high reactivity, it exists in combined form. Phosphorus plays a very important role in every living organism as well as it has various uses in the industrial, agricultural and commercial fields.

PRACTICE QUESTIONS RELATED TO PHOSPHORUS

Frequently Asked Questions on Phosphorus

The frequently asked questions on Phosphorus are given below:

Q.1. What happens when you have too much phosphorus in your body?
Ans: When your blood contains too much phosphorus, your body balances it by removing calcium from your bones. As a result, your bones can become weak and unhealthy. If the bones are unhealthy, they are more likely to break and cause other problems.

Q.2. What does phosphorus do to the human body?
Ans: Phosphorus is essential for the formation of teeth and bones. It is required for the body to produce protein, which is required for cell and tissue growth, maintenance, and repair.

Q.3. What is phosphorus in food?
Ans: Phosphorus is a mineral that is part of every cell in your body. Phosphorus can be found in phosphorus-rich foods such as dairy products, sunflower and pumpkin seeds, nuts, bran cereals, lentils, oatmeal beans. It is also found in seafood, and chicken, and turkey.

Q.4. What foods to avoid if phosphorus is high?
Ans: If your phosphorus level is high, avoid phosphorus-rich foods such as dairy products, sunflower and pumpkin seeds, nuts, bran cereals, lentils, oatmeal beans, seafood, and chicken and turkey.

Q.5. What are the symptoms of high phosphorus?
Ans: The symptoms of high phosphorus include joint pain, muscle pain, and muscle fatigue. High phosphorus levels can cause extreme constipation, nausea, vomiting, and diarrhoea.

Q.6. What is phosphate used for?
Ans: Phosphate is used as a fertilizer.

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