Halogen

LegendThe halogens (/ˈhælədʒən, ˈheɪ-, -loʊ-, -ˌdʒɛn/) are a group in the periodic table consisting of five chemically related elements: Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (At). The artificially created element 117 (Tennessine, Ts) may also be a halogen. In the modern IUPAC nomenclature, this group is known as group 17. The symbol X is often used generically to refer to any halogen.Fluorine F Atomic Number: 9 Atomic Weight: 18.9984032 Melting Point: 53.63 KBoiling Point: 85.03 KSpecific mass: 0.001696 g/cm3 Electronegativity: 3.98Chlorine Cl Atomic Number: 17 Atomic Weight: 35.453 Melting Point: 172.31 K Boiling Point: 239.11 KSpecific mass: 0.003214 g/cm3 Electronegativity: 3.16Bromine Br Atomic Number: 35 Atomic Weight: 79.904 Melting Point: 266.05 K Boiling Point: 332.0 KSpecific mass: 3.122 g/cm3 Electronegativity: 2.96Iodine I Atomic Number: 53 Atomic Weight: 126.90447 Melting Point: 386.65 K Boiling Point: 475.4 KSpecific mass: 4.93 g/cm3 Electronegativity: 2.66Astatine At Atomic Number: 85 Atomic Weight: Melting Point: 575.15 K Boiling Point: 610 KSpecific mass: 7 g/cm3 Electronegativity: 2.2Tennessine Ts Atomic Number: 117 Atomic Weight: Melting Point: ? 573–773 K Boiling Point: ? 823 K Specific mass: ? g/cm3 Electronegativity: ? The halogens (/ˈhælədʒən, ˈheɪ-, -loʊ-, -ˌdʒɛn/) are a group in the periodic table consisting of five chemically related elements: Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (At). The artificially created element 117 (Tennessine, Ts) may also be a halogen. In the modern IUPAC nomenclature, this group is known as group 17. The symbol X is often used generically to refer to any halogen. The name 'halogen' means 'salt-producing'. When halogens react with metals they produce a wide range of salts, including calcium fluoride, sodium chloride (common table salt), silver bromide and potassium iodide. The group of halogens is the only periodic table group that contains elements in three of the main states of matter at standard temperature and pressure. All of the halogens form acids when bonded to hydrogen. Most halogens are typically produced from minerals or salts. The middle halogens, that is chlorine, bromine and iodine, are often used as disinfectants. Organobromides are the most important class of flame retardants. Elemental halogens are dangerous and can be lethally toxic. The fluorine mineral fluorospar was known as early as 1529. Early chemists realized that fluorine compounds contain an undiscovered element, but were unable to isolate it. In 1860, George Gore, an English chemist, ran a current of electricity through hydrofluoric acid and probably produced fluorine, but he was unable to prove his results at the time. In 1886, Henri Moissan, a chemist in Paris, performed electrolysis on potassium bifluoride dissolved in anhydrous hydrogen fluoride, and successfully isolated fluorine. Hydrochloric acid was known to alchemists and early chemists. However, elemental chlorine was not produced until 1774, when Carl Wilhelm Scheele heated hydrochloric acid with manganese dioxide. Scheele called the element 'dephlogisticated muriatic acid', which is how chlorine was known for 33 years. In 1807, Humphry Davy investigated chlorine and discovered that it is an actual element. Chlorine combined with hydrochloric acid, as well as sulfuric acid in certain instances created chlorine gas which was a poisonous gas during World War I. It displaced oxygen in contaminated areas and replaced common oxygenated air with the toxic chlorine gas. In which the gas would burn human tissue externally and internally, especially the lungs making breathing difficult or impossible depending on level of contamination. Bromine was discovered in the 1820s by Antoine Jérôme Balard. Balard discovered bromine by passing chlorine gas through a sample of brine. He originally proposed the name muride for the new element, but the French Academy changed the element's name to bromine. Iodine was discovered by Bernard Courtois, who was using seaweed ash as part of a process for saltpeter manufacture. Courtois typically boiled the seaweed ash with water to generate potassium chloride. However, in 1811, Courtois added sulfuric acid to his process, and found that his process produced purple fumes that condensed into black crystals. Suspecting that these crystals were a new element, Courtois sent samples to other chemists for investigation. Iodine was proven to be a new element by Joseph Gay-Lussac. In 1931, Fred Allison claimed to have discovered element 85 with a magneto-optical machine, and named the element Alabamine, but was mistaken. In 1937, Rajendralal De claimed to have discovered element 85 in minerals, and called the element dakine, but he was also mistaken. An attempt at discovering element 85 in 1939 by Horia Hulubei and Yvette Cauchois via spectroscopy was also unsuccessful, as was an attempt in the same year by Walter Minder, who discovered an iodine-like element resulting from beta decay of polonium. Element 85, now named astatine, was produced successfully in 1940 by Dale R. Corson, K.R. Mackenzie, and Emilio G. Segrè, who bombarded bismuth with alpha particles. In 2010, a team led by nuclear physicist Yuri Oganessian involving scientists from the JINR, Oak Ridge National Laboratory, Lawrence Livermore National Laboratory, and Vanderbilt University successfully bombarded berkelium-249 atoms with calcium-48 atoms to make tennessine-294. As of 2019, it is the most recent element to be discovered.