Oxygen is an odourless, colourless, and tasteless gas required by all living species (Humans and Animals). Living beings breathe oxygen and exhale Carbon Dioxide, which plants, in turn, use as a source of carbon and return oxygen to the atmosphere. It is referred to as a life-sustaining gas because oxygen in our body is used to generate energy when we breathe.

Do you know that it will continue to burn indefinitely when something catches fire? However, when we put something over it, the fire goes out. This is because Oxygen gas promotes combustion, and when the supply of oxygen is cut off, the fire goes out. In this article, we will know more about oxygen and its importance.

What is Oxygen?

Oxygen is the chemical element with the symbol and atomic number \(8.\) It is non-metal and present in the \({\rm{1}}{{\rm{6}}^{{\rm{th}}}}\) group of the periodic table. Group \(16\) is also known as the Oxygen family.

Oxygen atoms are unable to exist independently. Therefore, it combines with another Oxygen atom and forms a diatomic molecule called dioxygen. Naturally occurring Oxygen consists of three isotopes, such as Oxygen-\(16,\) Oxygen-\(17,\) and Oxygen-\(18.\) It is the most abundant gas on the Earth and present in the form as well as in the combined form. In the state, about \(21\% \) Oxygen by volume is present in the atmosphere and in the combined state, about \(88%\) by weight it is present in water, about \(50%\) by weight it is present in Earth crust, and tissues of plants and animals contain \(50 – 70\% \) of Oxygen by weight.

Oxygen Element

Oxygen is a non-metallic gaseous element present in the \({\rm{1}}{{\rm{6}}^{{\rm{th}}}}\) group of the periodic table. This group is also known as the chalcogen family. Joseph Priestley first discovered the oxygen element in \(1774.\) He prepared Oxygen by focusing the rays of the sun on mercuric oxide and named the gas dephlogisticated air.

Some physical properties of Oxygen element are:

Property	Oxyzen
Chemical symbol	O
Atomic number	\(8\)
Atomic mass\({\rm{/gm\;mo}}{{\rm{l}}^{{\rm{ – 1}}}}\)	\(16.00\)
Block	P
Group	\(16\)
Priod	\(2\)
Electronic configuration	\(\left[ {{\rm{He}}} \right]{\rm{2}}{{\rm{s}}^{\rm{2}}}{\rm{2}}{{\rm{p}}^{\rm{4}}}\)
Electron gain enthalpy \({{\rm{\Delta }}_{{\rm{eg}}}}{\rm{H\;/\;kJ\;mo}}{{\rm{l}}^{{\rm{ – 1}}}}{\rm{\;}}\)	\(-141\)
Ionisation enthalpy \({\rm{kJ\;mo}}{{\rm{l}}^{{\rm{ – 1}}}}\)	\(1314\)
Electronegativity	\(3.50\)
Melting point in K	\(55\)
Boiling point in K	\(90\)
Oxyzen states	\( – 2,{\rm{ }} – 1,{\rm{ }}1,{\rm{ }}2\)
Density \(\left( {{\rm{g/c}}{{\rm{m}}^{\rm{3}}}} \right)\)	\(0.001308\)

Uses of Oxygen

1. Dioxygen is essential for the survival of life on Earth. All living beings in respiration use it.
2. Oxygen cylinders are used in hospitals for artificial respiration, mountaineering, and high altitude flying.
3. Oxygen is used in oxyacetylene welding, and to make oxy-hydrogen torches are used for cutting metals.
4. Liquid Oxygen is used as fuel in rockets.
5. Due to its oxidation nature, it is used in metallurgical processes to remove metals’ impurities.
6. In coal mining, a mixture of liquid Oxygen and charcoal powder is used as an explosive.

Properties of Oxygen

Physical Properties

1. It is a colourless, odourless, and tasteless gas.
2. It is only slightly soluble in water \(49\,{\text{mL}}\) of gas dissolves in \({\rm{1 L}}\) at STP). But the little dissolved Oxygen in water is responsible for the survival of aquatic organisms.
3. It can be absorbed to a significant degree in alkaline pyrogallol.
4. It is slightly dense than air and is paramagnetic in nature.

Chemical Properties

Dioxygen is quite stable at room temperature due to the high bond dissociation energy. Therefore, the chemical reaction of dioxygen requires initiation by external heating.

Reaction with Metals: Oxygen reacts with metals under different conditions to form metal oxides.

1. Reaction with active metals: Active metals like sodium, potassium, etc., reacts with Oxygen at ordinary temperature and form their oxides.
\({\rm{4Na + \;}}{{\rm{O}}_{\rm{2}}}{\rm{\;}} \to {\rm{2N}}{{\rm{a}}_{\rm{2}}}{\rm{O\;}}\left( {{\rm{Sodium\;oxide}}} \right)\)

2. Reaction with magnesium: When magnesium is burnt in dioxygen, magnesium oxide is formed with a dazzling white light.
\({\rm{2Mg + \;}}{{\rm{O}}_{\rm{2}}} \to {\rm{2MgO\;}}\left( {{\rm{Magnesium\;oxide}}} \right)\)

3. Reaction with ordinary metals: The metals like iron and aluminium combine with Oxygen on heating to form their oxides.

Reaction with Non-Metals: Several non-metals burn brightly in dioxygen and produce their corresponding oxides. For example,

1. The reaction of sulphur with Oxygen: When sulphur burns in the presence of Oxygen, sulphur dioxide is formed, which is acidic in nature.
\({\rm{S + \;}}{{\rm{O}}_{\rm{2}}}{\rm{\;}} \to {\rm{S}}{{\rm{O}}_{\rm{2}}}\) (sulphur dioxide)

2. The reaction of carbon with limited Oxygen: When carbon is burned in the presence of limited Oxygen, carbon monoxide is formed.
\({\rm{2C + \;}}{{\rm{O}}_{\rm{2}}}\left( {{\rm{limited}}} \right){\rm{\;}} \to {\rm{2CO\;}}\left( {{\rm{carbon\;monoxide}}} \right)\)

3. The reaction of carbon with excess Oxygen: When carbon is burned in the presence of excess Oxygen, carbon dioxide is formed.
\({\rm{C + \;}}{{\rm{O}}_{\rm{2}}}\left( {{\rm{excess}}} \right){\rm{\;}} \to {\rm{C}}{{\rm{O}}_{\rm{2}}}{\rm{\;}}\left( {{\rm{Carbon\;dioxide}}} \right)\)

Reaction with Compounds: Oxygen acts as an oxidizing agent. It oxidises many compounds under suitable conditions. For example,

1. Reaction with ammonia: It oxidises ammonia into nitric oxide at \(1073\,{\text{K}}\) in the presence of catalyst platinum.
\({\rm{4N}}{{\rm{H}}_{\rm{3}}}{\rm{ + \;5}}{{\rm{O}}_{\rm{2}}} \to {\rm{\;4NO + 6}}{{\rm{H}}_{\rm{2}}}{\rm{O}}\)

2. Reaction with Sulphur dioxide: Dioxygen oxidises Sulphur dioxide to Sulphur trioxide at \({\rm{725 K}}\) in the presence of finely divided platinum.
\({\rm{2S}}{{\rm{O}}_{\rm{2}}}\left( {\rm{g}} \right){\rm{ + \;}}{{\rm{O}}_{\rm{2}}}\left( {\rm{g}} \right){\rm{\;}} \to {\rm{\;2S}}{{\rm{O}}_{\rm{3}}}\left( {\rm{g}} \right)\)

3. Reaction with hydrogen chloride: It oxidises hydrogen chloride gas into chlorine gas at \({\rm{700 k}}\) in the presence of catalyst cupric chloride.
\({\rm{4HCl}}\left( {\rm{g}} \right){\rm{ + 5}}{{\rm{O}}_{\rm{2}}}\left( {\rm{g}} \right){\rm{\;}} \to {\rm{\;\;2}}{{\rm{H}}_{\rm{2}}}{\rm{O}}\left( {\rm{g}} \right){\rm{ + \;2C}}{{\rm{l}}_{\rm{2}}}\left( {\rm{g}} \right)\)

Occurrence of Oxygen

Oxygen is the most plentiful element in Earth’s crust (around \(46\) per cent of the Earth’s mass). It occupies \(21\) per cent as a proportion of volume in the atmosphere, and by weight, in seawater, it is \(89\) per cent. It occurs as \({{\rm{O}}_2}\) molecules and, to a limited extent, as \({{\rm{O}}_3}\) (ozone) molecules in the air. It forms about \(20\% \) of the mass of the air. In the rocks, it occurs in the form of oxides that are either acidic or basic.

Summary

From this article, we can conclude that  Oxygen is the most abundant element on the Earth, and it exists in both and combined forms. The abundance of  Oxygen on the Earth is essential for the survival of life on the Earth, as well as it has various uses in our day-to-day life, in industrial and commercial fields.

Related Topics to Study

1. Oxygen Formula 2. Carbon 3. Modern Periodic Table 4. Periodic Classification of Elements

FAQs

Question-1: Who named Oxygen?
Answer: Antoine-Laurent Lavoisier named Oxygen in \(1775-77.\)

Question-2: Is Oxygen soluble in water?
Answer: Oxygen is only slightly soluble in water.  About \({\rm{49 ml}}\) of  Oxygen gas dissolves in \(1\) Litre of water at STP (Standard temperature and pressure).

Question-3: What are the physical properties of Oxygen?
Answer: The physical properties of  Oxygen gas are:

1. It is a colourless, odourless, and tasteless gas.
2. It is only slightly soluble in water ( \({\rm{49 ml}}\) of gas dissolves in \(1\) L at STP). But the little dissolved Oxygen in water is responsible for the survival of aquatic organisms.
3. It can be absorbed to a significant degree in alkaline pyrogallol.
4. It is slightly more dense than air and is paramagnetic in nature.

Question-4: What does \({{\rm{O}}_{\rm{2}}}\) stand for?
Answer: It stands for dioxygen molecule. It contains two Oxygen atoms.

Question-5: What is the use of Oxygen?
Answer: Following are the uses of Oxygen:

1. It is used by all living beings in respiration.
2. Liquid Oxygen is used as rocket fuel.
3. Oxygen cylinders are used in hospitals for artificial breathing.
4. It is used in oxyacetylene welding.
5. Due to its oxidation nature, it is used in metallurgical processes for removing the impurities of metals.

Question-6: Is Oxygen \({{\rm{O}}_{\rm{2}}}\) or just \(O\)?
Answer: The elemental form of Oxygen is O but, Oxygen atoms cannot exist independently. Therefore, it combines with other Oxygen atoms and forms the diatomic molecule.

Question-7: Where is Oxygen found in nature?
Answer: In nature, Oxygen is found in both the state and in the combined state. In the state, about \({\rm{21\% }}\) Oxygen by volume is present in the atmosphere and in the combined state, about \({\rm{88\% }}\) by weight it is present in water, about 50% by weight it is present in Earth crust, and tissues of plants and animals contain \({\rm{50 – 70\% }}\) of Oxygen by weight.

Question -8: Is Oxygen found naturally?
Answer: Yes, it is found in the atmosphere, water, Earth crust, and tissues of plants and animals.

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