What are the properties reactions and uses of chlorine
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 Element Structure Properties and Uses
1. What is Cl in chemistry?
Cl is the chemical symbol for chlorine, a halogen element with atomic number 17. Chlorine is a greenish-yellow, highly reactive non-metal found in Group 17 of the periodic table. Key facts include:
- Atomic number: 17
- Electronic configuration: 1s2 2s2 2p6 3s2 3p5
- Valency: Usually 1
- Exists as a diatomic molecule: Cl2
2. What is the atomic number and mass of chlorine (Cl)?
The atomic number of chlorine is 17 and its average atomic mass is approximately 35.5 u. The atomic number (17) means chlorine has 17 protons and 17 electrons in a neutral atom. Its atomic mass is 35.5 u because it exists naturally as a mixture of two isotopes:
- 35Cl (about 75%)
- 37Cl (about 25%)
3. Why does chlorine exist as Cl2?
Chlorine exists as Cl2 because each chlorine atom needs one more electron to complete its octet and forms a single covalent bond with another chlorine atom. Each Cl atom has 7 valence electrons (3s2 3p5). By sharing one pair of electrons:
- Each atom attains a stable octet configuration.
- A single covalent bond is formed: Cl–Cl.
4. What is the valency of chlorine (Cl)?
The most common valency of chlorine is 1 because it needs one electron to complete its octet. Chlorine has 7 valence electrons and typically gains one electron to form the chloride ion Cl-. However, chlorine can also show variable oxidation states such as -1, +1, +3, +5, and +7 in different compounds like:
- HCl (–1)
- HClO (+1)
- HClO3 (+5)
5. How is chlorine gas (Cl2) prepared in the laboratory?
Chlorine gas is commonly prepared in the laboratory by oxidizing concentrated hydrochloric acid with manganese dioxide. The balanced chemical equation is:
- MnO2(s) + 4HCl(aq) → MnCl2(aq) + 2H2O(l) + Cl2(g)
- MnO2 acts as an oxidizing agent.
- HCl is oxidized to chlorine gas.
6. What is the reaction between chlorine and sodium?
Chlorine reacts vigorously with sodium to form sodium chloride (NaCl). The balanced equation is:
- 2Na(s) + Cl2(g) → 2NaCl(s)
- Sodium loses one electron to form Na+.
- Chlorine gains one electron to form Cl-.
7. What are the main uses of chlorine (Cl) in chemistry and industry?
Chlorine is mainly used as a disinfectant, bleaching agent, and raw material in chemical manufacturing. Important uses include:
- Water purification to kill bacteria and pathogens.
- Manufacture of bleaching powder (CaOCl2).
- Production of PVC (polyvinyl chloride).
- Preparation of hydrochloric acid (HCl).
8. What is the difference between chlorine (Cl2) and chloride (Cl-)?
Chlorine (Cl2) is a neutral diatomic molecule, while chloride (Cl-) is a negatively charged ion. The main differences are:
- Cl2: Greenish-yellow gas, covalent molecule, strong oxidizing agent.
- Cl-: Anion formed by gaining one electron, found in salts like NaCl.
9. How does chlorine react with water?
Chlorine reacts with water to form hydrochloric acid and hypochlorous acid. The balanced equation is:
- Cl2(g) + H2O(l) ⇌ HCl(aq) + HClO(aq)
- HClO (hypochlorous acid) is a strong oxidizing agent.
- It destroys bacteria and microorganisms in water.
10. What are the physical properties of chlorine (Cl2)?
Chlorine is a greenish-yellow, toxic gas with a pungent smell at room temperature. Its main physical properties are:
- Molecular form: Cl2
- State at room temperature: Gas
- Density: Heavier than air
- Melting point: About −101.5°C
- Boiling point: About −34.0°C
