Why Is Chlorine Important in Chemistry?
Chlorine is a chemical element that was discovered in 1774 by Carl Wilhelm Scheele. Initially, he mistakenly thought it contained oxygen. Chlorine got its name in 1810 by Humphry Davy, who claimed that it was in fact an element. Chlorine is also denoted with the symbol Cl (Cl full form is chlorine). The chlorine atomic number is 17. Chlorine belongs to group 17 (or VII-A) elements of the periodic table and the symbol of chlorine is ‘Cl’.
Being the second lightest halogen, it is positioned between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is present in gaseous form at room temperature with a yellowish-green appearance. Chlorine formula (chemical formula of chlorine) is Cl2. The electronic configuration of chlorine is 1s22s22p63s23p5 (or \[\left [Ne\right ]\] 3s2 3p5).
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Atomic Structure of Chlorine
As depicted in the picture, the first and second electron shells of chlorine atoms are completely filled up with 2 and 8 electrons respectively. The outermost shell contains 7 electrons in total. As the outermost shell has one electron less from attaining the nearest noble gas configuration, its tendency is to form an anion; ‘Cl-’.
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Some of the physical and Chemical properties of Chlorine are listed below.
Properties of Chlorine
Physical Properties
Chemical Properties
Chlorine Uses
Some use of chlorine gas is given below.
Water Treatment
The chemistry of chlorine has helped to a large extent in keeping the drinking water and water in pools safe. Before chlorine-based disinfectants became popular, waterborne diseases like typhoid, dysentery, cholera and hepatitis A took thousands of lives every year. Chlorine-based disinfectants for pools and spas are really helpful in killing waterborne pathogens and keeping the water safe from causing illness. This way, it prevents diseases like diarrhoea, rashes on the swimmer’s ear or skin etc.
Food
Chlorine plays an important role in the abundant production of crops by protecting them against pests. It is also useful in keeping the kitchen surfaces germ free and safe to prepare food on them. E. coli, salmonella and hosts of some other foodborne germs are disinfected easily with chlorine-based disinfectants.
Household Disinfectant
Chlorine is widely used in manufacturing bleaches which is further very helpful in cleaning, disinfecting and brightening clothes, kitchen and washroom surfaces. Germs found on household surfaces causing stomach bugs (norovirus), seasonal flu and other diseases can be easily killed with diluted bleach solutions.
Healthcare and Medicines
The chemistry of chlorine is quite important in pharmaceutical industries. In the manufacture of many medicines including those to control cholesterol, fix allergy symptoms and relieve arthritis pain use of chlorine is crucial. Several medical devices including blood bags, surgical stitches, contact lenses, safety glasses and some respiratory equipment also have the application of chlorine chemistry in their manufacturing process.
Energy and Environment
Chlorine is used in the process of manufacturing various devices used in the extraction of renewable energy resources. Chlorine is used in the purification and extraction of silicon from sand grains which are then useful in the fabrication of solar cells and panels. The blades of wind turbines are made up of chlorine-based epoxy resins.
Advanced Technology
The chemistry of chlorine is important in the manufacture of advanced technology equipment such as high-speed processors which are used in computers, laptops and smartphones, etc. It is useful in manufacturing refrigerants that are used in air conditioners. High-performance magnets and hybrid car batteries are other such applications of chlorine.
Defence and Law Enforcement
The manufacture of bullet-resistant vests, night vision goggles, parachutes, cockpit canopies as well as missile guidance techniques have applications of chlorine chemistry. This equipment is used in the defence and enforcement of the law.
Building and Construction
Durable paints for walls and ceilings, energy-efficient vinyl windows, plastic foam insulation for home heating and air conditioning systems, etc. are some example applications of chlorine chemistry in building and construction-related components which help in improving the efficiency and durability of the construction.
Transportation
The seat cushions, airbags, brake fluids, bumpers, shatter-resistant windows, cables and wires, navigation systems, steel hulls etc. used in automobiles, trains and planes have wide applications of chlorine chemistry. These components add comfort and safety for the passengers.
Did You Know?
Chlorine alone is toxic and harmful while its compound; ‘NaCl’ (common salt) is completely safe to intake (of course in very small amounts).
Gaseous chlorine is about 2.5 times denser than the air mixture. Hence, in a container filled with air with chlorine, it will have a tendency to settle down at the bottom.
Conclusion
Chlorine is a chemical element that was discovered in 1774 by Carl Wilhelm Scheele. Chlorine atomic number 17, belongs to group 17 (or VII-A) elements of the periodic table and the symbol of chlorine is ‘Cl’. It is in gaseous form at room temperature, yellowish-green in colour, toxic with a suffocating smell and soluble in water. Chlorine is used in domains of food, healthcare, water treatment etc. It has wide applications in manufacturing bleaches, drugs, pest killers, defence equipment, automobile components, silicon-based electronics, construction hardware etc.
FAQs on Chlorine (Cl): Atomic Structure, Properties & Applications
1. What is the main difference between a chlorine atom (Cl) and a chlorine molecule (Cl₂)?
A chlorine atom, shown as Cl, is a single, individual atom of the element. However, because it is very reactive, it rarely exists alone. In its natural state, two chlorine atoms share electrons to form a stable pair. This pair is called a chlorine molecule, or chlorine gas, and is written as Cl₂. So, Cl represents the single atom, while Cl₂ represents the gas we typically work with.
2. Is chlorine a metal or a non-metal?
Chlorine (Cl) is a non-metal. It is located in Group 17 of the periodic table, a family of elements known as the halogens. Like other non-metals, chlorine is a poor conductor of heat and electricity and is highly reactive chemically.
3. Why is chlorine added to drinking water and swimming pools?
Chlorine is a very effective disinfectant. When small, controlled amounts are added to water, it kills harmful germs like bacteria and viruses that can cause illness. This process, known as chlorination, makes tap water safe to drink and keeps swimming pools clean by preventing the growth of algae and other microorganisms.
4. What are some important uses of chlorine besides water purification?
Chlorine is a crucial chemical in many industries. Its main uses include:
- Manufacturing plastics, especially PVC (polyvinyl chloride).
- Acting as a powerful bleaching agent for paper and fabrics.
- Producing solvents used for cleaning and degreasing metals.
- Creating antiseptics, insecticides, and many life-saving medicines.
5. Where is chlorine naturally found on Earth?
Chlorine is too reactive to exist by itself in nature. It is most commonly found chemically combined with other elements. The largest source is sodium chloride (NaCl), which is the ordinary table salt found dissolved in seawater and in large underground salt deposits.
6. Why is chlorine gas considered so highly reactive?
Chlorine's high reactivity is due to its atomic structure. A chlorine atom has seven electrons in its outer shell and is most stable when it has a full set of eight. This strong tendency to gain one more electron makes it very eager to react with other elements, either by taking an electron from a metal or by sharing electrons with another non-metal.
7. What is the difference between chlorine, chloride, and chlorine gas?
These terms are often confused but refer to different forms:
- Chlorine (Cl) refers to the element itself or a single atom.
- Chlorine gas (Cl₂) is its natural molecular form, where two atoms are bonded together. This is the toxic, greenish-yellow gas.
- Chloride (Cl⁻) is a chlorine atom that has gained an electron, giving it a negative charge. This is the stable ion found in compounds like salt.
8. How can toxic chlorine gas be used safely in household bleach?
Household bleach does not contain pure chlorine gas. It is a water-based solution of a compound called sodium hypochlorite (NaClO). In this compound, the chlorine is chemically bonded and stable. It works as a strong oxidising agent, which allows it to kill germs and remove stains effectively and safely for household use, without releasing toxic gas.
