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Group 17: Halogens

Updated: Oct 3, 2020

Halogens are basically Nonmetals and Highly reactive elements which exists as diatomic molecules.


 

Fluorine(F):


Fluorine is the most reactive and most electronegative of all the chemical elements. The only elements it doesn't vigorously react with are oxygen, helium, neon, and argon. It is one of the few elements that will form compounds with noble gases xenon, krypton, and radon.


Checkout the Blog: Colorful Chemistry Beautiful Science of the Periodic table to know the importance of terms you need on the given picture.

Physical properties:


  • It is pale greenish-yellow in color with a pungent odor.

  • It is highly toxic.

  • It is a non-metal.


Chemical properties:


  • It is very corrosive .

  • It can burn metals, glass, ceramics, carbon, and water .

  • It is highly reactive, participating in reactions with virtually all organic and inorganic substances.


Occurrence:


Fluorine does not occur as a free element in nature, because it is very reactive element. It is readily found in minerals in the Earth's crust including fluorspar, fluorapatite, and cryolite. The main source of commercial fluorine is fluorspar (which is also called fluorite). The majority of the world's fluorspar is supplied by China and Mexico. It is obtained by electrolyzing a solution of potassium hydrogen fluoride in anhydrous hydrogen fluoride in container of transparent fluorspar or metal.

Uses:


  • Fluorine and its compounds are used in producing uranium.

  • Fluorine, in the form of fluorite, is added during smelting to help reduce the melting points of metals.

  • Fluorochlorohydrocarbons are used in refrigeration applications.

  • Fluorine is used to produce many chemicals, including several high-temperature plastics.

  • Fluoride is helpful in preventing tooth decay, hence used in toothpaste.

Discovery:


French chemist Henri Moissan is the first who successfully isolated the element in 1886. The name fluorine comes from the Latin and French fluere: flow. The name was suggested by English chemist Sir Humphry Davy, based on its presence in fluoric acid.

Fascinating Facts :


  • Henri Moissan earned the 1906 Nobel Prize in Chemistry for being the chemist who finally successfully isolated fluorine.

  • Fluorine is the 13th most common element in the Earth's crust.

  • The bond formed between carbon and fluorine to make fluorocarbons is the strongest bond in organic chemistry and is very stable.



 

Chlorine(Cl):


Chlorine is the second element in the seventeenth column of the periodic table. It is a member of the halogen group. It has 17 electrons and 17 protons with 7 valence electrons in the outer shell. It dissolve in water, but also react with water as it dissolves. Chlorine will react with all the other elements except the noble gases.

Checkout the Blog: Colorful Chemistry Beautiful Science of the Periodic table to know the importance of terms you need on the given picture.

Physical properties:


  • It exists as a diatomic green gas.

  • It has intense disagreeable suffocating odor.

  • It is very poisonous.

  • It is a non-metal.


Chemical properties:


  • It is highly reactive and combines readily with nearly all other elements except noble gases.


Occurrence:


Chlorine is very reactive and hence not found in its free form in nature. It is only found combined with other elements chiefly sodium in the form of common salt (NaCl), but also in carnallite, and sylvite. Chlorides make up much of the salt dissolved in the earth's oceans: about 1.9 % of the mass of seawater is chloride ions. It is extracted from chlorides through oxidation and electrolysis.

Uses:


  • Chlorine is an important chemical in water purification, in disinfectants, in bleach and in mustard gas.

  • Chlorine is also used widely in the manufacture of many products like in paper product production, antiseptic, dyestuffs, food, insecticides, paints, petroleum products, plastics, medicines, textiles, solvents, and many other consumer products. Chlorine is involved in beaching wood pulp for paper making, bleach is also used industrially to remove ink from recycle paper.

  • Chlorine often imparts many desired properties in an organic compound when it is substituted for hydrogen (synthetic rubber), so it is widely use in organic chemistry, in the production of chlorates, chloroform, carbon tetrachloride etc.


Discovery:


Discovered in 1774 by Carl Wilhelm Scheele,many years he thought it contained oxygen. Chlorine was given its name in 1810 by Humphry Davy, who proved that it was in fact an element. The name chlorine is derived from chloros, meaning green, referring to the color of the gas.


Fascinating Facts :

  • Chlorine gas is two and one half times as heavy as air.

  • Chlorofluorocarbons or CFCs were once widely used in air conditioners and spray cans but Unfortunately, they contributed to destroying the ozone layer and have been mostly banned.

 


Bromine(Br):


Bromine is chemically less active than chlorine and fluorine but is more active than iodine. its compounds are similar to those of the other halogens. Bromine is soluble in organic solvents and in water.


Checkout the Blog: Colorful Chemistry Beautiful Science of the Periodic table to know the importance of terms you need on the given picture.

Physical properties:


  • At room temperature bromine is a brownish-red liquid.

  • It has strong suffocating odor.

  • It is a non-metal.


Chemical properties:


  • Bromine is chemically less active than chlorine and fluorine but is more active than iodine.


Occurrence:


Bromine is a naturally occurring element that can be found in many inorganic substances.

In diffuse crustal rock bromine naturally occurs as bromide salts. Bromine salts have accumulated in sea water (85 ppm), from which bromine is extracted. World production of bromine is more than 300.000 tonnes per year; the three main producing countries are US, Istrael and the UK. In this last case it is extracted from sea water at a plant on the coast of Anglesey, Wales.



Uses:


  • Bromine is used in industry to make organobromo compounds. organobromines are used as insecticides, in fire extinguishers and to make pharmaceuticals.

  • Bromine is used in making fumigants, dyes, flameproofing agents, water purification compounds, sanitizes, medicinals, agents for photography.

  • It is used in brominated vegetable oil.

  • It is used as emulsifier in many citrus-flavoured solft drinks.

Discovery:


Balard was credited with the discovery in 1826 describing the Bromine as new element and named it after the greek word for stench, bromos.


Fascinating Facts:

  • There are 23 known radioactive isotopes of bromine.

  • Today, bromine plays a vital role in the production of flame retardant materials.

 

Iodine(I):


Iodine is the fourth element in the seventeenth column of the periodic table. It is classified as a halogen . Iodine atoms have 53 electrons and 53 protons with 7 valence electrons in the outer shell.


Checkout the Blog: Colorful Chemistry Beautiful Science of the Periodic table to know the importance of terms you need on the given picture.

Physical properties:


  • It is a non-metal.

  • Slate grey, lustrous, solid element.


Chemical properties:


  • Iodine dissolves in some solvents, such as carbon tetrachloride and it is only slightly soluble in water.

  • Iodine can form compounds with many elements. for example sodium and potassium.


Occurrence:


Iodine can be found naturally in air, water and soil. The most important sources of natural iodine are the oceans. About 400.000 tonnes of iodine escape from the oceans every year as iodide. Some ocean plants such as seaweed have a high concentration of iodine. It is also found in underground brines near oil and natural gas reserves.

Uses:

  • Iodine is used in medical treatment as tincture and iodioform,

  • It is employed in the preparation of certain drugs.

  • It used in the manufacture of some printing inks and dyes.

  • Silver iodine is used in photography.

  • Iodine is added to almost all the table salt and is used as a supplement to animal feed.

  • It is also an ingredient of water purification tablets that are used for drinking water preparation.

Discovery:


Iodine was first discovered and isolated by French chemist Bernard Courtois in 1811, when running experiments on seaweed. The French chemist Gay-Lussac who first named iodine as a new element and suggested the name.Iodine gets its name from the Greek word "iodes" which means "violet."


Fascinating Facts:


  • Iodine in air can combine with water particles and precipitate into water or soils. Iodine in soils will combine with organic matter and remain in the same place for a long time. Plants that grow on these soils may absorb iodine. Cattle and other animals will absorb iodine when they eat these plants.

  • Iodine is a building material of thyroid hormones that are essential for growth, the nervous system and the metabolism. Humans that eat little to no bread can experience iodine shortages. The function of the thyroid gland will than slow down and the thyroid gland will start swelling up. This phenomenon is called struma. This condition is rare now as table salt is dosed with a little iodide. Large quantities of iodine can be dangerous because the thyroid gland will labour too hastily. This affects the entire body; it causes disturbed heartbeats and loss of weight.


 

Astatine(At):


It has been little researched because all its isotopes have short half lives. All that is known about the element has been estimated from knowing its position in the periodic table below iodine and by studying its chemistry in extreme diluted solutions.

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Physical properties:


  • It is the heaviest known halogen.


Chemical properties:


  • Astatine is a highly radioactive element.

  • Its chemical properties are believed to be similar to those of iodine.

Occurrence:


The amount of astatine in the earth's crust at any particular time is less than 30 grams and only a few micrograms have ever been artificially produced. This, together with its short lifetime, leaves no reason for considering the effects of astatine.

Uses:


  • Due to short life time astatine has no recorded uses.


Discovery:


It is discovered by D.R. Corson in 1940.


Fascinating Facts:


Astatine is never encountered outside nuclear facilities or research laboratories as it has very short lifetime to study.


 

Tennessine(Ts):


All about this element are guesses based on its position in the periodic table.


Checkout the Blog: Colorful Chemistry Beautiful Science of the Periodic table to know the importance of terms you need on the given picture.



 



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