Properties: Selenium has an atomic radius of 117 pm, a melting point of 220.5°C, boiling point of 685°C, with oxidation states of 6, 4, and -2. 78.971. You may not further copy, alter, distribute or otherwise use any of the materials from this Site without the advance, written consent of the RSC. The mass of an atom relative to that of carbon-12. You're listening to Chemistry in its element brought to you by. Selenium was discovered by Jöns Jacob Berzelius at Stockholm in 1817. CAS number First ionisation energyThe minimum energy required to remove an electron from a neutral atom in its ground state. Tellurium, its dioxide, and its tetrachloride are strong catalysts for air oxidation of carbon above 500 °C. Atomic number He had shares in a sulfuric acid works and he was intrigued by a red-brown sediment which collected at the bottom of the chambers in which the acid was made. Selene, moon) Discovered by Berzelius in 1817, who found it associated with tellurium, named for the earth. Bond enthalpy (kJ mol−1)A measure of how much energy is needed to break all of the bonds of the same type in one mole of gaseous molecules. Group. Selenium can be prepared with either an amorphous or a crystalline structure. Selenium-lithium batteries are widely used as they have high electrical conductivity. Selenium is used to make pigments for ceramics, paint and plastics. Our Periodic Element comparison tool allows you to compare Periodic Elements properties side by side for all 118 elements | SchoolMyKids Interactive Dynamic Periodic Table, Periodic Table Element Comparison tool, Element Property trends It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. Each entry has a full citation identifying its source. The element is named after Selene, the Greek goddess of the moon. Selenium is found in a few rare minerals such as crooksite and clausthalite. This is where the artist explains his interpretation of the element and the science behind the picture. Download our free Periodic Table app for mobile phones and tablets. The oxidation state of an atom is a measure of the degree of oxidation of an atom. Black selenium is converted to grey selenium when temperature is increased to around 180°C. In excess it is carcinogenic and teratogenic (disturbs the development of an embryo or foetus). Selenium atoms have 34 electrons and the shell structure is 2.8.18.6. Krypton is a fictional planet in the DC Comics universe, and the native world of the super-heroes Superman, Supergirl, and Krypto the "super dog". Half of the distance between two unbonded atoms of the same element when the electrostatic forces are balanced. In no event shall the RSC be liable for any damages including, without limitation, indirect or consequential damages, or any damages whatsoever arising from use or loss of use, data or profits, whether in action of contract, negligence or other tortious action, arising out of or in connection with the use of the material available from this Site. It is a soft metalloid similar to sulfur, unaffected by water and soluble in alkalis and nitric acid. Indeed, the newest and most promising class of mass produced solar cells are copper indium gallium selenide. The total electrical charge of the nucleus is therefore +Ze, where e … Selenium Element: Selenium is the chemical in the 16th group and 4th period of the periodic table. The treatment for this was a shampoo containing selenium sulphide, surprising to me because I thought that selenium was highly toxic. A horizontal row in the periodic table. Medium = substitution is possible but there may be an economic and/or performance impact Medium = substitution is possible but there may be an economic and/or performance impact, Low = substitution is possible with little or no economic and/or performance impact, If you wish to use the Images in a manner not permitted by these terms and conditions please contact the Publishing Services Department. But I save the best occurrence of selenium in nature for last. A measure of the propensity of a substance to evaporate. ... Selenium acts as a catalyst in some microorganisms. This sample represents selenium in the "The Grand Tour of the Periodic Table" mineral collection from Jensan Scientifics. I'm Chris Smith, thank you for listening and goodbye. In fact a little investigation showed me that it was perfectly safe in small amounts. While selenium is not a metallic element, gray selenium is a good photoconductor, and was used in early photocells. The image is of a crescent moon against a cratered surface. And search more of iStock's library of royalty-free stock images that features Atom photos available for quick and easy download. Melting point A measure of how difficult it is to deform a material. Electron configuration The images may not be posted on any website, shared in any disc library, image storage mechanism, network system or similar arrangement. Half of the distance between two atoms within a single covalent bond. Also intriguing to me was a recent study indicating that selenium deficient soils may play a role in susceptibility to HIV/AIDS in Africa. Data for this section been provided by the British Geological Survey. Recently 21 polo horses died from selenium overdose in Florida, the result of a veterinary pharmacist overdoing it in mixing the drugs. Electronegativity (Pauling scale)The tendency of an atom to attract electrons towards itself, expressed on a relative scale. Log in, This site uses cookies to improve your experience. Selenium is a chemical element with atomic number 34 which means there are 34 protons in its nucleus. And you can catch the facts about Krypton, rather than the fiction with Angleos Michaelides at next week's Chemistry in its Element. That was Cambridge University's Bernie Bulkin with the story of Selenium. Selenium is an essential trace element for some species, including humans. Specific heat capacity is the amount of energy needed to change the temperature of a kilogram of a substance by 1 K. A measure of the stiffness of a substance. The description of the element in its natural form. It can also convert AC electricity to DC electricity, so is extensively used in rectifiers. Selenium in its allotropic red form is added to glass to give it a scarlet color, but it also can be used to remove the greenish tint sometimes found in glass due to iron compounds. How slighted is this important element! The number of atoms of the element per 1 million atoms of the Earth’s crust. Isotopes It decreases electrical resistance with increased illumination. Selenium gets its name from the Greek word "selene," which means "moon." Half of the distance between two unbonded atoms of the same element when the electrostatic forces are balanced. The role of the element in humans, animals and plants. It is often found in combination with metals like mercury, copper, silver or lead. The mass of an atom relative to that of carbon-12. Selenium is a non-metal and is sometimes considered as a metalloid. The temperature at which the solid–liquid phase change occurs. This Site has been carefully prepared for your visit, and we ask you to honour and agree to the following terms and conditions when using this Site. These values were determined using several different methods. Trivial name of Selenium is chalcogens*. Krypton has been portrayed consistently as having been destroyed just after Superman's flight from the planet, with exact details of its destruction varying by time period, writers and franchise. When I was in my early 20s I developed a dry scalp condition for a few years, probably a result of anxiety over research grants I was trying to obtain. Elements are organised into blocks by the orbital type in which the outer electrons are found. At first he thought it was the element tellurium because it gave off a strong smell of radishes when heated, but he eventually realised that it was in fact a new element. The arrangements of electrons above the last (closed shell) noble gas. Se is a non-metal. Selenium is a nonmetal with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. Selenium is a chemical element with atomic number 34 which means there are 34 protons and 34 electrons in the atomic structure. Butyl seleno mercaptan is the essential ingredient of skunk smell, and is certainly a contender for the title of the worst smelling compound. Oxygen group element, any of the six chemical elements making up Group 16 (VIa) of the periodic classification—namely, oxygen (O), sulfur (S), selenium (Se), tellurium (Te), polonium (Po), and livermorium (Lv). The RSC maintains this Site for your information, education, communication, and personal entertainment. The chemical behavior and reactions of these elements are similar. Selenium is used as a toner for photographing purpose. Atoms of the same element with different numbers of neutrons. Density is the mass of a substance that would fill 1 cm3 at room temperature. It is defined as the equilibrium pressure exerted by the gas produced above a substance in a closed system. It rarely occurs in its elemental state or as pure ore compounds in the Earth's crust. The rationale is that low selenium levels are associated with weakened immune systems, since with lack of antioxidant capacity there is stress on the immune system. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. Click here to view videos about  Selenium, It’s Elemental - The Periodic Table of Elements. He became intrigued by ore from a mine near Zalatna which had a metallic sheen and which he suspected was native antimony or bismuth. Most of the world’s selenium is obtained from the anode muds produced during the electrolytic refining of copper. Commercial use of the Images will be charged at a rate based on the particular use, prices on application. Fully descriptive writeups. Selenium is a chemical element in the periodic table that has the symbol Se and atomic number 34. Hello, this week flaky scalps, skunks, dead polo ponies and an element that makes you stink of garlic. It was Berzelius who discovered selenium in 1817, as an impurity in sulphuric acid. The chemical symbol for Selenium is Se. Density is the mass of a substance that would fill 1 cm. Selenium exists in only trace amounts around us. A vertical column in the periodic table. Some elements exist in several different structural forms, called allotropes. Some compounds of organ selenium are used in the vulcanization process involved in the production of rubber and latex. Look up chemical element names, symbols, atomic masses and other properties, visualize trends, or even test your elements knowledge by playing a periodic table game! It is possible selenium was first observed in about the year 1300 by the alchemist Arnold of Villanova. Block Selenium is a chemical element with symbol Se and atomic number 34. The nucleus is composed of protons and neutrons. The atomic number of each element increases by one, reading from left to right. Where more than one isotope exists, the value given is the abundance weighted average. So it can clear up an itchy scalp but it might make you stink in the process. A horizontal row in the periodic table. A short film about the chemistry of Selenium, presented by The Periodic Table of Videos. Subsequently, selenium and various selenium compounds have been used in a variety of photoconductor and photovoltaic applications. It can convert AC electricity to DC electricity. Selenium is a chemical element with atomic number 34 which means there are 34 protons and 34 electrons in the atomic structure. Boiling point Selenium—from Ancient Greek σελήνη (selḗnē) "Moon" – was discovered in 1817 by Jöns Jacob Berzelius, who noted the similarity of the new element t… While some of the allotropic forms of selenium resemble those that we know well from study of sulphur, there are others that are different. Selenium is also used as an additive to make stainless steel. Crystalline monoclinic selenium is a deep red; crystalline hexagonal selenium, the most stable variety, is a metallic gray. It was discovered by Jons J. Berzelius in 1817. Most of these seem to indicate that if it is effective at all, it works somehow in conjunction with vitamin E, which, like selenium, plays an antioxidant role in the body. Berzelius … Each allotrope has different physical properties. Berzelius found that selenium was present in samples of tellurium and gave that element its characteristic smell. A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators. Selenium is a chemical element that is placed in the oxygen group of the periodic table. It was first observed by the Swedish scientist Jons Jacob Berzelius. At one time virtually all copying machines used selenium ; this has now been largely replaced by organic photoconductors. Selenium is found in a few rare minerals. Selenium trioxide (SeO 3) Interesting facts: It is similar to sulfur in its form and compounds. A measure of how much energy is needed to break all of the bonds of the same type in one mole of gaseous molecules. The name is derived from 'selene', the Greek name for the Moon. The Chemical Abstracts Service registry number is a unique identifier of a particular chemical, designed to prevent confusion arising from different languages and naming systems. Period A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators. History (Gr. High = substitution not possible or very difficult. Selenium is one of those all too common elements that is essential to life in small quantities, and very toxic in larger quantities. The color of amorphous selenium is either red (in powder form) or black (in vitreous form). It is given by the ratio of the shear stress to the shear strain. red selenium has here sub-forms, alpha, beta and gamma. Copyright of and ownership in the Images reside with Murray Robertson. It is indicated by the symbol Se and the atomic number of selenium is 34. The temperature at which the liquid–gas phase change occurs. It is used to make photocells. The element occurs in copper ores and rare minerals such as … Period. Once you have smelled it you will never forget it, nor underestimate the impact that this interesting element can have. Atomic Weight: 78.96. This is approximately the sum of the number of protons and neutrons in the nucleus. Selenium. The higher the value, the larger risk there is to supply. Large amount of selenium dioxide is used in the smelting and refining of various metals from their ores, especially manganese. 400 micrograms per day is set as the safe upper intake level in humans. Group The higher the value, the larger risk there is to supply. A vertical column in the periodic table. These muds are either roasted with sodium carbonate or sulfuric acid, or smelted with sodium carbonate to release the selenium. Selenium is added to synthetic rubber to improve resistance to abrasion, it has been added to brass, along with bismuth, to replace lead in pipes, and it is used, as sodium selenate, as an insecticide to stop attacks on flowering plants such as chrysanthemums and carnations. If you are in any doubt, please ask. You may browse, download or print out one copy of the material displayed on the Site for your personal, non-commercial, non-public use, but you must retain all copyright and other proprietary notices contained on the materials. 116. And when subjected to rapid melting, selenium acquires a black glass like allotropic form. Values are given for typical oxidation number and coordination. Visualize trends, 3D orbitals, isotopes, and mix compounds. Selenium: Symbol: Se: Atomic Number: 34: Atomic Weight: 78.971: Density: 4.819 g/cm 3: Melting Point: 221 °C: Boiling Point: 685 °C: Thermal properties: Phase: Solid: Melting Point: 221 °C: Boiling Point: … It is given by the ratio of the pressure on a body to the fractional decrease in volume. The temperature at which the solid–liquid phase change occurs. Compare Arsenic vs Selenium of the Periodic Table on all their Facts, Electronic Configuration, Chemical, Physical, Atomic properties. A higher recycling rate may reduce risk to supply. Selenium is a chemical element with the symbol Se and atomic number 34. Classified as a nonmetal, Selenium is a solid at room temperature. An integrated supply risk index from 1 (very low risk) to 10 (very high risk). Our selenium page has over 260 facts that span 106 different quantities. Uncombined elements have an oxidation state of 0. Selenium is toxic to the scalp fungus that causes dandruff so it is used in some anti-dandruff shampoos. A horizontal row in the periodic table. Welcome to "A Visual Interpretation of The Table of Elements", the most striking version of the periodic table on the web. Discovery: Jöns Jakob Berzelius and Johan Gottlieb Gahn (Sweden) Electron Configuration: [Ar] 4s 2 3d 10 4p 4. We know selenium is there, right under sulfur, in the periodic table, but it doesn't get much attention. These blocks are named for the characteristic spectra they produce: sharp (s), principal (p), diffuse (d), and fundamental (f). Periodic Table of Elements Element Selenium - Se. For more information on the Visual Elements image see the Uses and properties section below. All such documents and related graphics are provided "as is" without any representation or endorsement made and warranty of any kind, whether expressed or implied, including but not limited to the implied warranties of fitness for a particular purpose, non-infringement, compatibility, security and accuracy. In such cases we would ask you to sign a Visual Elements licence agreement, tailored to the specific use you propose. Relative atomic mass: 78.971 (8) Selenium was discovered by Jöns Jacob Berzelius (SE) in 1817. Nor shall the RSC be in any event liable for any damage to your computer equipment or software which may occur on account of your access to or use of the Site, or your downloading of materials, data, text, software, or images from the Site, whether caused by a virus, bug or otherwise. Some elements exist in several different structural forms, called allotropes. Political stability of top reserve holder. Please enable JavaScript to access the full features of the site. This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores. The atomic number of each element increases by one, reading from left to right. Murray Robertson is the artist behind the images which make up Visual Elements. But it's not all bad news. A measure of how difficult it is to compress a substance. The transition of a substance directly from the solid to the gas phase without passing through a liquid phase. Villanova lived from about 1235 to about 1310 and was trained in medicine at the Sorbonne in Paris, becoming physician to Pope Clement V. In the book Rosarium Philosophorum he describes red sulfur or ‘sulfu… Too little selenium can cause health problems, but too much is also dangerous. The atom consist of a small but massive nucleus surrounded by a cloud of rapidly moving electrons. Common chemical compounds are also provided for many elements. Comprehensive data on the chemical element Selenium is provided on this page; including scores of properties, element names in many languages, most known nuclides of Selenium. Selenium has atomic number 34, meaning each atom has 34 protons. 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