Chlorine | History, Properties & Uses

History and Discovery of Chlorine

In 1774, Swedish chemist Carl Wilhelm Scheele studied chlorine atoms in detail and the credit of this discovery goes to him. He produced chlorine by reacting MnO₂ with HCl.

4 HCl + MnO₂ → MnCl₂ + 2H₂O + Cl₂

His observations of the properties of chlorine were: The bleaching effect on litmus, deadly effect on insects. The yellow green color . The smell similar to aqua regia.

So, he called it dephlogisticated muriatic acid air since it is a gas and it came from hydrochloric acid (previously known as muriatic acid). He failed to establish chlorine as an element.

In 1809, Joseph Louis Gay-Lussac and Louis-Jacques Thenard tried to decompose dephlogisticated muriatic acid air by reacting it with charcoal to release the free element muriaticun. They were not successful and published a report in which they they considered the possibility that dephlogisticated muriatic acid air is an element, but were not covinced.

In 1810, Sir Humphry Davy tried the same experiment again, and he concluded that the substance was an element, and not a compound. He announced his results to Royal society on 15 November that year. He named that element “Chlorine” from the Greek word χλωρος (chlōros, “green-yellow”).

What is chlorine?

Chlorine is a chemical element with the symbol Cl, atomic number 17 and atomic mass 35.457. It is the second lightest element among all halogens. Chlorine is a halogen which lies between fluorine and bromine in the periodic table. It belongs to third period and 17th group in periodic table. Chlorine is a p-block element. It is a strong oxidising agent. Chlorine is extremely reactive element. It has highest electron affinity. It is strongly acidic in nature.

What is electronic configuration of chlorine?

Chlorine has 17 atomic number. So, it’s 17 electrons are distributed in the following way:

K shell = 2 electrons

L shell = 8 electrons

M shell = 7 electrons

Total electrons in chlorine are 17 and valence electrons are 7. The electronic configuration of chlorine can be written as 1s₂, 2s₂, 2p₆, 3s₂, 3p₅ or we can also write as [Ne]3s₂,3p₅.

Write some Properties of chlorine

• It is an extremely reactive element with a strong oxidizing agent.
• It’s electronic affinity is the highest among all the elements in the periodic table.
• Chlorine is a yellow green gas at room temperature.
• Melting and boiling points of chlorine gas are 171.6 K and 239.11 K respectively.
• It’s density is 3.2 g/L.
• On Pauling scale, chlorine’s electronegativity is 3.16.
• There are three main isotopes of chlorine. ³⁵Cl, ³⁶Cl, ³⁷Cl.
• Chlorine has similar properties to fluorine, bromine and iodine.
• It is a strong oxidising agent.
• It is intermediate in atomic radius between fluorine and and bromine.
• Chlorine is a very poor conductor of electricity.

Uses

• Chlorine is used to clean/disinfect water in pools.
• Chlorine is used as a bleaching agent during the production of paper and cloth.
• It is also used in cleaning products.
• It is used in the production of plastics, dyes, textiles, medicines and paints.
• Chlorine is also used in food industry.
• We also use chlorine in healthcare.
• It is used to produce drugs.
• We use chlorine to get rid of the smell of putrefaction.

Conclusive remarks

Chlorine was discovered by Carl Wilhelm Scheele and then it was proved as an element by Sir Humphry Davy. It is a chemical element with atomic number of 17 and atomic mass of 35.5. There are 7 electrons in the valence shell of chlorine with the electronic configuration of 1s₂, 2s₂, 2p₆, 3s₂, 3p₅. Having the highest electron affinity, it is an extremely reactive element with a strong oxidizing agent. Chlorine is a disinfectant and used to clean the water. Chlorine has a variety of uses in industries and labs.