"(He) is a colorless, odorless, tasteless, non-toxic, inert monatomic chemical element that heads the noble gas series in the periodic table and whose atomic number is 2. Its boiling and melting points are the lowest among the elements and it exists only as a gas except in extreme conditions. Helium was discovered in 1868 by French astronomer Pierre Janssen, who first detected the substance as an unknown yellow spectral line signature in light from a solar eclipse. In 1903, large reserves of helium were found in the natural gas fields of the United States, which is by far the largest"
"for example, hydrogen (""water-producing""), oxygen (""acid-producing""), nitrogen (""soda-producing""), bromine (""stink""), and argon (""no reaction"") were based on Greek roots, while the names of iodine and chlorine were derived from the Greek words for their characteristic colors. Indium, rubidium, and thallium were similarly named for the colors of particular lines in their emission spectra. Iridium, which forms compounds of many different colors, takes its name from ""iris"", the Latin for ""rainbow"". The noble gases have all been named for their origin or properties. Helium comes from the Greek ""helios"", meaning ""sun"" because it was first detected as a line in the"
"spectrum of the sun (it is not known why the suffix ""-ium"", which is used for metals, was chosen). The other noble gases are neon (""new""), argon (""slow, lazy""), krypton (""hidden""), xenon (""stranger""), and radon (""from radium""). Many more elements have been given names that have little or nothing to do with their properties. Elements have been named for celestial bodies (helium, selenium, tellurium, for the sun, moon, and earth; cerium and palladium for Ceres and Pallas, two asteroids). They have been named for mythological figures, including Titans in general (titanium) and Prometheus in particular (promethium); Roman and Greek gods"
"body before being found on the earth. Lockyer and the English chemist Edward Frankland named the element with the Greek word for the Sun, ἥλιος (""helios""). At the great Indian eclipse of 1868 that occurred in Guntur, Janssen also demonstrated the gaseous nature of the red prominences, and devised a method of observing them under ordinary daylight conditions. One main purpose of his spectroscopic inquiries was to answer the question whether the Sun contains oxygen or not. An indispensable preliminary was the virtual elimination of oxygen-absorption in the Earth's atmosphere, and his bold project of establishing an observatory on the"
"the elements krypton and neon. They found xenon in the residue left over from evaporating components of liquid air. Ramsay suggested the name ""xenon"" for this gas from the Greek word ""ξένον"" [xenon], neuter singular form of ""ξένος"" [xenos], meaning 'foreign(er)', 'strange(r)', or 'guest'. In 1902, Ramsay estimated the proportion of xenon in the Earth's atmosphere to be one part in 20 million. During the 1930s, American engineer Harold Edgerton began exploring strobe light technology for high speed photography. This led him to the invention of the xenon flash lamp in which light is generated by passing brief electric current"
"the mineral fluorospar, which was used as a flux in metal working. Chlorine's name comes from the Greek word ""chloros"", meaning ""greenish-yellow"". Bromine's name comes from the Greek word ""bromos"", meaning ""stench"". Iodine's name comes from the Greek word ""iodes"", meaning ""violet"". Astatine's name comes from the Greek word ""astatos"", meaning ""unstable"". Tennessine is named after the US state of Tennessee. The halogens show trends in chemical bond energy moving from top to bottom of the periodic table column with fluorine deviating slightly. (It follows trend in having the highest bond energy in compounds with other atoms, but it has"
"the Greek word ""khalkόs"" (χαλκός) principally meaning copper (the term was also used for bronze/brass, any metal in the poetic sense, ore or coin), and the Latinised Greek word ""genēs"", meaning ""born"" or ""produced"". Sulfur has been known since antiquity, and oxygen was recognized as an element in the 18th century. Selenium, tellurium and polonium were discovered in the 19th century, and livermorium in 2000. All of the chalcogens have six valence electrons, leaving them two electrons short of a full outer shell. Their most common oxidation states are −2, +2, +4, and +6. They have relatively low atomic radii,"
"see list of states of matter. The only chemical elements that are stable diatomic homonuclear molecules at STP are hydrogen (H), nitrogen (N), oxygen (O), and two halogens: fluorine (F) and chlorine (Cl). When grouped together with the monatomic noble gases – helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) – these gases are called ""elemental gases"". The word ""gas"" was first used by the early 17th-century Flemish chemist Jan Baptist van Helmont. He identified carbon dioxide, the first known gas other than air. Van Helmont's word appears to have been simply a phonetic transcription"
"is due to the very high nuclear binding energy (per nucleon) of helium-4 with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay. Most helium in the universe is helium-4, the vast majority of which was formed during the Big Bang. Large amounts of new helium are being created by nuclear fusion of hydrogen in stars. Helium is named for the Greek Titan of the Sun, Helios. It was first detected as an unknown yellow spectral line signature in sunlight during a"
"can regarded as a portmanteau of ""borax"" and ""carbon"". Aluminium was named by Humphry Davy in the early 1800s. It is derived from the Greek word ""alumen"", meaning bitter salt, or the Latin ""alum"", the mineral. Gallium is derived from the Latin ""Gallia"", referring to France, the place of its discovery. Indium comes from the Latin word ""indicum"", meaning indigo dye, and refers to the element's prominent indigo spectroscopic line. Thallium, like indium, is named after the Greek word for the color of its spectroscopic line: ""thallos"", meaning a green twig or shoot. ""Nihonium"" is named after Japan (""Nihon"" in"
"by Jöns Jakob Berzelius in his system of atomic symbols, and is an abbreviation of the element's New Latin name ""natrium"", which refers to the Egyptian ""natron"", a natural mineral salt mainly consisting of hydrated sodium carbonate. Natron historically had several important industrial and household uses, later eclipsed by other sodium compounds. Sodium imparts an intense yellow color to flames. As early as 1860, Kirchhoff and Bunsen noted the high sensitivity of a sodium flame test, and stated in Annalen der Physik und Chemie: In a corner of our 60 m room farthest away from the apparatus, we exploded 3"
"""Phosphorus"" in Ancient Greece was the name for the planet Venus and is derived from the Greek words (φῶς = light, φέρω = carry), which roughly translates as light-bringer or light carrier. (In Greek mythology and tradition, Augerinus (Αυγερινός = morning star, still in use today), Hesperus or Hesperinus (΄Εσπερος or Εσπερινός or Αποσπερίτης = evening star, still in use today) and Eosphorus (Εωσφόρος = dawnbearer, not in use for the planet after Christianity) are close homologues, and also associated with Phosphorus-the-planet). According to the Oxford English Dictionary, the correct spelling of the element is phosphorus. The word phosphorous is"
"to use the term ""element (στοιχεῖον, ""stoicheion"")"" in reference to air, fire, earth, and water. The ancient Greek word for element, ""stoicheion"" (from ""stoicheo"", ""to line up"") meant ""smallest division (of a sun-dial), a syllable"", as the composing unit of an alphabet it could denote a letter and the smallest unit from which a word is formed. A similar alphabetic metaphor may be the origin of the equivalent Latin word ""elementum"" (from which the English word comes), possibly based on the names of the letters 'l', 'm', and 'n', though the validity of this idea is debated. In his ""On"
"of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day. and are the most often studied NMR-active nuclei, having spins of and respectively. Hg is the modern chemical symbol for mercury. It comes from ""hydrargyrum"", a Latinized form of the Greek word ὑδράργυρος (""hydrargyros""), which is a compound word meaning ""water-silver"" (from ὑδρ- ""hydr-"", the root of ὕδωρ, ""water,"" and ἄργυρος ""argyros"" ""silver"") – since it is liquid like water and shiny like silver. The element was named after the Roman god Mercury, known for his speed and mobility. It is associated with the"
"Xenon Xenon is a chemical element with symbol Xe and atomic number 54. It is a colorless, dense, odorless noble gas found in the Earth's atmosphere in trace amounts. Although generally unreactive, xenon can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate, the first noble gas compound to be synthesized. Xenon is used in flash lamps and arc lamps, and as a general anesthetic. The first excimer laser design used a xenon dimer molecule (Xe) as the lasing medium, and the earliest laser designs used xenon flash lamps as pumps. Xenon is used to search for"
"which the pentafluorophenyl group is an example, exist, and are named according to IUPAC nomenclature. Phenyl is derived from the French word ""phényle"", which in turn derived from Greek ""phaino"" – ""shining"", as the first phenyl compounds named were byproducts of making and refining various gases used for lighting. According to McMurry:""The word is derived from the Greek pheno (“I bear light”), commemorating the discovery of benzene by Michael Faraday in 1825 from the oily residue left by the illuminating gas used in London street lamps."" Phenyl compounds are derived from benzene (CH), at least conceptually and often in terms"
"Bromine Bromine is a chemical element with symbol Br and atomic number 35. It is the third-lightest halogen, and is a fuming red-brown liquid at room temperature that evaporates readily to form a similarly coloured gas. Its properties are thus intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig (in 1825) and Antoine Jérôme Balard (in 1826), its name was derived from the Ancient Greek βρῶμος (""stench""), referencing its sharp and disagreeable smell. Elemental bromine is very reactive and thus does not occur free in nature, but in colourless soluble crystalline mineral halide salts,"
"Ar) is the third element in group 18 of the periodic table (the noble gases). Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide. Nearly all of this argon is radiogenic argon-40 derived from the decay of potassium-40 in the Earth's crust. In the universe, argon-36 is by far the most common argon isotope, being the preferred argon isotope produced by stellar nucleosynthesis in supernovas. The name ""argon"" is derived from the Greek word αργον meaning ""lazy"" or ""the inactive one"", a reference to the fact that the element"
"was associated with metals and metal-bearing rock in general; copper, and its alloy bronze, was one of the first metals to be used by humans. Oxygen's name comes from the Greek words ""oxy genes"", meaning ""acid-forming"". Sulfur's name comes from either the Latin word ""sulfurium"" or the Sanskrit word ""sulvere""; both of those terms are ancient words for sulfur. Selenium is named after the Greek goddess of the moon, Selene, to match the previously-discovered element tellurium, whose name comes from the Latin word ""telus"", meaning earth. Polonium is named after Marie Curie's country of birth, Poland. Livermorium is named for"
"the identification of its atomic number 89. The name actinium originates from the Ancient Greek ""aktis, aktinos"" (ακτίς, ακτίνος), meaning beam or ray. Its symbol Ac is also used in abbreviations of other compounds that have nothing to do with actinium, such as acetyl, acetate and sometimes acetaldehyde. Actinium is a soft, silvery-white, radioactive, metallic element. Its estimated shear modulus is similar to that of lead. Owing to its strong radioactivity, actinium glows in the dark with a pale blue light, which originates from the surrounding air ionized by the emitted energetic particles. Actinium has similar chemical properties to lanthanum"
"Gallium(III) sulfide Gallium(III) sulfide, GaS, is a compound of sulfur and gallium, that is a semiconductor that has applications in electronics and photonics. There are four polymorphs, α (hexagonal), α' (monoclinic), β(hexagonal) and γ(cubic). The alpha form is yellow. The crystal structures are related to those of ZnS with gallium in tetrahedral positions. The alpha and beta forms are isostructural with their aluminium analogues. The similarity in crystal form of gamma- with sphalerite (zinc blende), ZnS is believed to explain the enrichment of gallium in sphalerite ores. GaS can prepared by reacting the elements at high temperature or as a"
"taken from Greek mythology, meaning ""light-bearer"" (Latin ""Lucifer""), referring to the ""Morning Star"", the planet Venus. The term ""phosphorescence"", meaning glow after illumination, derives from this property of phosphorus, although the word has since been used for a different physical process that produces a glow. The glow of phosphorus is caused by oxidation of the white (but not red) phosphorus — a process now called chemiluminescence. Together with nitrogen, arsenic, antimony, and bismuth, phosphorus is classified as a pnictogen. Phosphorus is essential for life. Phosphates (compounds containing the phosphate ion, PO) are a component of DNA, RNA, ATP, and phospholipids."
"with alpha particles. In 1811, the German chemist Johann Schweigger proposed that the name ""halogen"" – meaning ""salt producer"", from αλς [als] ""salt"" and γενειν [genein] ""to beget"" – replace the name ""chlorine"", which had been proposed by the English chemist Humphry Davy. Davy's name for the element prevailed. However, in 1826, the Swedish chemist Baron Jöns Jacob Berzelius proposed the term ""halogen"" for the elements fluorine, chlorine, and iodine, which produce a sea-salt-like substance when they form a compound with an alkaline metal. Fluorine's name comes from the Latin word ""fluere"", meaning ""to flow"", because it was derived from"
"the Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in the Earth's crust. In the universe, argon-36 is by far the most common argon isotope, as it is the most easily produced by stellar nucleosynthesis in supernovas. The name ""argon"" is derived from the Greek word , neuter singular form of meaning ""lazy"" or ""inactive"", as a reference to the fact that the element undergoes almost no chemical reactions. The complete octet (eight electrons) in the outer atomic shell makes argon stable and resistant to bonding with other elements. Its triple point temperature of 83.8058 K is"
"Chrysene Chrysene is a polycyclic aromatic hydrocarbon (PAH) with the molecular formula that consists of four fused benzene rings. It is a natural constituent of coal tar, from which it was first isolated and characterized. It is also found in creosote at levels of 0.5-6 mg/kg. The name ""chrysene"" originates from Greek ""Χρύσoς"" (""chrysos""), meaning ""gold"", and is due to the golden-yellow color of the crystals of the hydrocarbon, thought to be the proper color of the compound at the time of its isolation and characterization. However, high purity chrysene is colorless, the yellow hue being due to the traces"
"alkaline material the name """"lithion""/""lithina"""", from the Greek word ""λιθoς"" (transliterated as ""lithos"", meaning ""stone""), to reflect its discovery in a solid mineral, as opposed to potassium, which had been discovered in plant ashes, and sodium, which was known partly for its high abundance in animal blood. He named the metal inside the material ""lithium"". Arfwedson later showed that this same element was present in the minerals spodumene and lepidolite. In 1818, Christian Gmelin was the first to observe that lithium salts give a bright red color to flame. However, both Arfwedson and Gmelin tried and failed to isolate the"
"is instead used in many languages, such as French, Russian, and Turkish, and appears in the English names of some nitrogen compounds such as hydrazine, azides and azo compounds. Nitrogen is the lightest member of group 15 of the periodic table, often called the pnictogens. The name comes from the Greek πνίγειν ""to choke"", directly referencing nitrogen's asphyxiating properties. It is a common element in the universe, estimated at about seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bind to form dinitrogen, a colourless and odorless"
"Neon Neon is a chemical element with symbol Ne and atomic number 10. It is a noble gas. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air. It was discovered (along with krypton and xenon) in 1898 as one of the three residual rare inert elements remaining in dry air, after nitrogen, oxygen, argon and carbon dioxide were removed. Neon was the second of these three rare gases to be discovered and was immediately recognized as a new element from its bright red emission spectrum. The name neon is derived from"
"element carbon. Even for elements such as nitrogen having only one stable allotrope, a name such as dinitrogen may be used to indicate its molecular structure N as well as its elemental composition. The naming of chemical compounds comprising more than one element is a complex subject, discussed at length in the article on chemical nomenclature. Naming of chemical elements Chemical elements may be named from various sources: sometimes based on the person who discovered it, or the place it was discovered. Some have Latin or Greek roots deriving from something related to the element, for example some use to"
"factories, coal-burning power plants, and metal sewers. The main source of elevated thallium concentrations in water is the leaching of thallium from ore processing operations. Thallium Thallium is a chemical element with symbol Tl and atomic number 81. It is a gray post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861, in residues of sulfuric acid production. Both used the newly developed method of flame spectroscopy, in which thallium produces a notable green spectral line. Thallium, from Greek"
"Krypton Krypton (from ""the hidden one"") is a chemical element with symbol Kr and atomic number 36. It is a member of group 18 (noble gases) elements. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere and is often used with other rare gases in fluorescent lamps. With rare exceptions, krypton is chemically inert. Krypton, like the other noble gases, is used in lighting and photography. Krypton light has many spectral lines, and krypton plasma is useful in bright, high-powered gas lasers (krypton ion and excimer lasers), each of which resonates and amplifies a single"
"Its name derives from the Greek roots ὀξύς ""oxys"", ""acid"", literally ""sharp"", referring to the sour taste of acids and -γενής ""-genes"", ""producer"", literally ""begetter"", because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work ""Pneumatica"", Philo observed that inverting a vessel over a burning candle and surrounding the vessel's neck with water resulted in some water rising into the neck. Philo"
"of the solar nebula from which the sun and planets are believed to have formed. In 2006, Dale Cruikshank of NASA/Ames Research Center (a New Horizons co-investigator) and his colleagues announced the spectroscopic discovery of ethane on Pluto's surface. Ethane Ethane ( or ) is an organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petrochemical by-product of petroleum refining. Its chief use is as feedstock for ethylene production. Related compounds may be formed by"