Oxygen - Atomic Number - O (2024)

Discoverer: Cavendish, Henry

Element Category: Non Metal

Hydrogenis a chemical element withatomic number1which means there are 1 protons and 1 electrons in the atomic structure. Thechemical symbolfor Hydrogen isH.

With a standard atomic weight of circa 1.008, hydrogen is the lightest element on the periodic table. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass.

Discoverer: Ramsey, Sir William and Cleve, Per Teodor

Element Category: Noble gas

Helium is a chemical element with atomic number 2 which means there are 2 protons and 2 electrons in the atomic structure. The chemical symbol for Helium is He.

It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements.

Discoverer: Arfvedson, Johan August

Element Category: Alkali metal

Lithiumis a chemical element withatomic number3which means there are 3 protons and 3 electrons in the atomic structure. Thechemical symbolfor Lithium isLi.

It is a soft, silvery-white alkali metal. Under standard conditions, it is the lightest metal and the lightest solid element. Like all alkali metals, lithium is highly reactive and flammable, and is stored in mineral oil.

Discoverer: Vauquelin, Nicholas Louis

Element Category: Alkaline earth metal

Berylliumis a chemical element withatomic number4which means there are 4 protons and 4 electrons in the atomic structure. Thechemical symbolfor Beryllium isBe.

Beryllium is a hard, grayish metal naturally found in mineral rocks, coal, soil, and volcanic dust. The commercial use of beryllium requires the use of appropriate dust control equipment and industrial controls at all times because of the toxicity of inhaled beryllium-containing dusts that can cause a chronic life-threatening allergic disease in some people called berylliosis.

Discoverer: Davy, Sir H. and Thénard, L.-J. and Gay-Lussac, L.-J.

Element Category: Metalloids

Boronis a chemical element withatomic number5which means there are 5 protons and 5 electrons in the atomic structure. Thechemical symbolfor Boron isB.

Significant concentrations of boron occur on the Earth in compounds known as the borate minerals. There are over 100 different borate minerals, but the most common are: borax, kernite, ulexite etc. Natural boron consists primarily of two stable isotopes, 11B (80.1%) and 10B (19.9%). In nuclear industry boron is commonly used as a neutron absorber due to the high neutron cross-section of isotope 10B.

Discoverer: unknown

Element Category: Nonmetals

Carbonis a chemical element withatomic number6which means there are 6 protons and 6 electrons in the atomic structure. Thechemical symbolfor Carbon isC.

It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. Carbon is one of the few elements known since antiquity. Carbon is the 15th most abundant element in the Earth’s crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen.

Discoverer: Rutherford, Daniel

Element Category: Nonmetals

Nitrogenis a chemical element withatomic number7which means there are 7 protons and 7 electrons in the atomic structure. Thechemical symbolfor Nitrogen isN.

Nitrogen is a colourless, odourless unreactive gas that forms about 78% of the earth’s atmosphere. Liquid nitrogen (made by distilling liquid air) boils at 77.4 kelvins (−195.8°C) and is used as a coolant.

Discoverer: Priestley, Joseph and Scheele, Carl Wilhelm

Element Category: Nonmetals

Oxygenis a chemical element withatomic number8which means there are 8 protons and 8 electrons in the atomic structure. Thechemical symbolfor Oxygen isO.

Oxygen is a colourless, odourless reactive gas, the chemical element of atomic number 8 and the life-supporting component of the air. It is a member of the chalcogen group on the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium.

Discoverer: Moissan, Henri

Element Category: Nonmetals

Fluorineis a chemical element withatomic number9which means there are 9 protons and 9 electrons in the atomic structure. Thechemical symbolfor Fluorine isF.

Fluorine is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. As the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.

Discoverer: Ramsay, William and Travers, Morris

Element Category: Noble gas

Neonis a chemical element withatomic number10which means there are 10 protons and 10 electrons in the atomic structure. Thechemical symbolfor Neon isNe.

Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air.

Discoverer: Davy, Sir Humphry

Element Category: Alkali metal

Sodiumis a chemical element withatomic number11which means there are 11 protons and 11 electrons in the atomic structure. Thechemical symbolfor Sodium isNa.

Sodium is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table, because it has a single electron in its outer shell that it readily donates, creating a positively charged atom—the Na+ cation.

Discoverer: Black, Joseph

Element Category: Alkaline earth metal

Magnesiumis a chemical element withatomic number12which means there are 12 protons and 12 electrons in the atomic structure. Thechemical symbolfor Magnesium isMg.

Magnesium is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (group 2, or alkaline earth metals) of the periodic table: all group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure.

Discoverer: Oersted, Hans Christian

Element Category: Post-transition metals

Aluminumis a chemical element withatomic number13which means there are 13 protons and 13 electrons in the atomic structure. Thechemical symbolfor Aluminum isAl.

Aluminium is a silvery-white, soft, nonmagnetic, ductile metal in the boron group. By mass, aluminium makes up about 8% of the Earth’s crust; it is the third most abundant element after oxygen and silicon and the most abundant metal in the crust, though it is less common in the mantle below.

Discoverer: Berzelius, Jöns Jacob

Element Category: Metalloids

Siliconis a chemical element withatomic number14which means there are 14 protons and 14 electrons in the atomic structure. Thechemical symbolfor Silicon isSi.

Silicon is a hard and brittle crystalline solid with a blue-grey metallic lustre, it is a tetravalent metalloid and semiconductor.

Discoverer: Brandt, Hennig

Element Category: Nonmetal

Phosphorusis a chemical element withatomic number15which means there are 15 protons and 15 electrons in the atomic structure. Thechemical symbolfor Phosphorus isP.

As an element, phosphorus exists in two major forms—white phosphorus and red phosphorus—but because it is highly reactive, phosphorus is never found as a free element on Earth. At 0.099%, phosphorus is the most abundant pnictogen in the Earth’s crust.

Discoverer: unknown

Element Category: Nonmetal

Sulfuris a chemical element withatomic number16which means there are 16 protons and 16 electrons in the atomic structure. Thechemical symbolfor Sulfur isS.

Sulfur is abundant, multivalent, and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S8. Elemental sulfur is a bright yellow crystalline solid at room temperature. Chemically, sulfur reacts with all elements except for gold, platinum, iridium, tellurium, and the noble gases.

Discoverer: Scheele, Carl Wilhelm

Element Category: Nonmetal

Chlorineis a chemical element withatomic number17which means there are 17 protons and 17 electrons in the atomic structure. Thechemical symbolfor Chlorine isCl.

Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity, behind only oxygen and fluorine.

Discoverer: Ramsay, Sir William and Strutt, John (Lord Rayleigh)

Element Category: Noble gas

Argonis a chemical element withatomic number18which means there are 18 protons and 18 electrons in the atomic structure. Thechemical symbolfor Argon isAr.

Argon is the third-most abundant gas in the Earth’s atmosphere, at 0.934% (9340 ppmv). Argon is mostly used as an inert shielding gas in welding and other high-temperature industrial processes where ordinarily unreactive substances become reactive; for example, an argon atmosphere is used in graphite electric furnaces to prevent the graphite from burning.

Discoverer: Davy, Sir Humphry

Element Category: Alkali metal

Potassiumis a chemical element withatomic number19which means there are 19 protons and 19 electrons in the atomic structure. Thechemical symbolfor Potassium isK.

Potassium was first isolated from potash, the ashes of plants, from which its name derives. In the periodic table, potassium is one of the alkali metals. All of the alkali metals have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge – a cation, which combines with anions to form salts. Naturally occurring potassium is composed of three isotopes, of which 40K is radioactive.

Discoverer: Davy, Sir Humphry

Element Category: Alkaline earth metal

Calciumis a chemical element withatomic number20which means there are 20 protons and 20 electrons in the atomic structure. Thechemical symbolfor Calcium isCa.

Calcium is an alkaline earth metal, it is a reactive pale yellow metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium. It is the fifth most abundant element in Earth’s crust and the third most abundant metal, after iron and aluminium.

Discoverer: Nilson, Lars Fredrik

Element Category: Transition metals

Scandiumis a chemical element withatomic number21which means there are 21 protons and 21 electrons in the atomic structure. Thechemical symbolfor Scandium isSc.

Scandium is a silvery-white metallic d-block element, it has historically been sometimes classified as a rare-earth element, together with yttrium and the lanthanides.

Discoverer: Gregor, William

Element Category: Transition metals

Discoverer: Del Rio, Andrés Manuel (1801) and Sefström, Nils Gabriel (1830)

Element Category: Transition metals

Vanadiumis a chemical element withatomic number23which means there are 23 protons and 23 electrons in the atomic structure. Thechemical symbolfor Vanadium isV.

Vanadium is a hard, silvery grey, ductile, and malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer (passivation) stabilizes the free metal somewhat against further oxidation.

Discoverer: Vauquelin

Element Category: Transition metals

Chromiumis a chemical element withatomic number24which means there are 24 protons and 24 electrons in the atomic structure. Thechemical symbolfor Chromium isCr.

Chromium is a steely-grey, lustrous, hard and brittle metal4 which takes a high polish, resists tarnishing, and has a high melting point. A major development was the discovery that steel could be made highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel.

Discoverer: Gahn, Johan Gottlieb

Element Category: Transition metals

Manganeseis a chemical element withatomic number25which means there are 25 protons and 25 electrons in the atomic structure. Thechemical symbolfor Manganese isMn.

Manganese is a metal with important industrial metal alloy uses, particularly in stainless steels.

Discoverer: unknown

Element Category: Transition metals

Ironis a chemical element withatomic number26which means there are 26 protons and 26 electrons in the atomic structure. Thechemical symbolfor Iron isFe.

Iron is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth’s outer and inner core. It is the fourth most common element in the Earth’s crust. Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars.

Discoverer: Brandt, Georg

Element Category: Transition metals

Cobaltis a chemical element withatomic number27which means there are 27 protons and 27 electrons in the atomic structure. Thechemical symbolfor Cobalt isCo.

Cobalt is found in the Earth’s crust only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.

Discoverer: Cronstedt, Alex Fredrik

Element Category: Transition metals

Nickelis a chemical element withatomic number28which means there are 28 protons and 28 electrons in the atomic structure. Thechemical symbolfor Nickel isNi.

Nickel is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile.

Discoverer: unknown

Element Category: Transition metals

Copperis a chemical element withatomic number29which means there are 29 protons and 29 electrons in the atomic structure. Thechemical symbolfor Copper isCu.

Copper is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a reddish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins.

Discoverer: unknown

Element Category: Transition metals

Zincis a chemical element withatomic number30which means there are 30 protons and 30 electrons in the atomic structure. Thechemical symbolfor Zinc isZn.

In some respects zinc is chemically similar to magnesium: both elements exhibit only one normal oxidation state (+2), and the Zn2+ and Mg2+ ions are of similar size.

Discoverer: Lecoq de Boisbaudran, Paul-Émile

Element Category: Post-transition metals

Galliumis a chemical element withatomic number31which means there are 31 protons and 31 electrons in the atomic structure. Thechemical symbolfor Gallium isGa.

Gallium has similarities to the other metals of the group, aluminium, indium, and thallium. Gallium does not occur as a free element in nature, but as gallium(III) compounds in trace amounts in zinc ores and in bauxite.

Discoverer: Winkler, Clemens A.

Element Category: Metalloids

Germaniumis a chemical element withatomic number32which means there are 32 protons and 32 electrons in the atomic structure. Thechemical symbolfor Germanium isGe.

Germanium is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. Pure germanium is a semiconductor with an appearance similar to elemental silicon.

Discoverer: unknown

Element Category: Metalloids

Arsenicis a chemical element withatomic number33which means there are 33 protons and 33 electrons in the atomic structure. Thechemical symbolfor Arsenic isAs.

Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid.

Discoverer: Berzelius, Jöns Jacob

Element Category: Nonmetal

Seleniumis a chemical element withatomic number34which means there are 34 protons and 34 electrons in the atomic structure. Thechemical symbolfor Selenium isSe.

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. It rarely occurs in its elemental state or as pure ore compounds in the Earth’s crust.

Discoverer: Balard, Antoine-Jérôme

Element Category: Nonmetal

Bromineis a chemical element withatomic number35which means there are 35 protons and 35 electrons in the atomic structure. Thechemical symbolfor Bromine isBr.

Bromine 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.

Discoverer: Ramsay, Sir William and Travers, Morris

Element Category: Noble gas

Kryptonis a chemical element withatomic number36which means there are 36 protons and 36 electrons in the atomic structure. Thechemical symbolfor Krypton isKr.

Krypton 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.

Discoverer: Bunsen, Robert Wilhelm and Kirchhoff, Gustav Robert

Element Category: Alkali metals

Rubidiumis a chemical element withatomic number37which means there are 37 protons and 37 electrons in the atomic structure. Thechemical symbolfor Rubidium isRb.

Rubidium is a soft, silvery-white metallic element of the alkali metal group, with an atomic mass of 85.4678. Elemental rubidium is highly reactive, with properties similar to those of other alkali metals, including rapid oxidation in air.

Discoverer: Crawford, Adair

Element Category: Alkaline earth metals

Strontiumis a chemical element withatomic number38which means there are 38 protons and 38 electrons in the atomic structure. Thechemical symbolfor Strontium isSr.

Strontium is an alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly reactive chemically.

Discoverer: Gadolin, Johan

Element Category: Transition metals

Yttriumis a chemical element withatomic number39which means there are 39 protons and 39 electrons in the atomic structure. Thechemical symbolfor Yttrium isY.

Yttrium is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a “rare-earth element”.

Discoverer: Klaproth, Martin Heinrich

Element Category: Transition metals

Discoverer: Hatchet, Charles

Element Category: Transition metals

Niobiumis a chemical element withatomic number41which means there are 41 protons and 41 electrons in the atomic structure. Thechemical symbolfor Niobium isNb.

Niobium is a soft, grey, ductile transition metal, often found in the minerals pyrochlore (the main commercial source for niobium) and columbite.

Discoverer: Scheele, Carl Welhelm

Element Category: Transition metals

Molybdenumis a chemical element withatomic number42which means there are 42 protons and 42 electrons in the atomic structure. Thechemical symbolfor Molybdenum isMo.

Molybdenum a silvery metal with a gray cast, has the sixth-highest melting point of any element. It readily forms hard, stable carbides in alloys, and for this reason most of world production of the element (about 80%) is used in steel alloys, including high-strength alloys and superalloys.

Discoverer: Perrier, Carlo and Segrè, Emilio

Element Category: Transition metals

Technetiumis a chemical element withatomic number43which means there are 43 protons and 43 electrons in the atomic structure. Thechemical symbolfor Technetium isTc.

Technetium is the lightest element whose isotopes are all radioactive; none are stable. Nearly all technetium is produced synthetically, and only minute amounts are found in the Earth’s crust. The chemical properties of this silvery gray, crystalline transition metal are intermediate between rhenium and manganese.

Discoverer: Klaus, Karl Karlovich

Element Category: Transition metals

Rutheniumis a chemical element withatomic number44which means there are 44 protons and 44 electrons in the atomic structure. Thechemical symbolfor Ruthenium isRu.

Ruthenium is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemicals.

Discoverer: Wollaston, William Hyde

Element Category: Transition metals

Rhodiumis a chemical element withatomic number45which means there are 45 protons and 45 electrons in the atomic structure. Thechemical symbolfor Rhodium isRh.

Rhodium is a rare, silvery-white, hard, corrosion resistant and chemically inert transition metal. It is a noble metal and a member of the platinum group.

Discoverer: Wollaston, William Hyde

Element Category: Transition metals

Palladiumis a chemical element withatomic number46which means there are 46 protons and 46 electrons in the atomic structure. Thechemical symbolfor Palladium isPd.

Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.

Discoverer: unknown

Element Category: Transition metals

Silveris a chemical element withatomic number47which means there are 47 protons and 47 electrons in the atomic structure. Thechemical symbolfor Silver isAg.

Silver is a soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earth’s crust in the pure, free elemental form (“native silver”), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite.

Discoverer: Stromeyer, Prof. Friedrich

Element Category: Transition metals

Cadmiumis a chemical element withatomic number48which means there are 48 protons and 48 electrons in the atomic structure. Thechemical symbolfor Cadmium isCd.

Cadmium is a soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. In nuclear industry cadmium is commonly used as a thermal neutron absorber due to very high neutron absorption cross-section of 113Cd. 113Cd has specific absorption cross-section.

Discoverer: Reich, Ferdinand and Richter, Hieronymus

Element Category: Post-transition metals

Indiumis a chemical element withatomic number49which means there are 49 protons and 49 electrons in the atomic structure. Thechemical symbolfor Indium isIn.

Indium is a post-transition metal that makes up 0.21 parts per million of the Earth’s crust. Very soft and malleable, indium has a melting point higher than sodium and gallium, but lower than lithium and tin. Chemically, indium is similar to gallium and thallium.

Discoverer: unknown

Element Category: Post-transition metals

Tinis a chemical element withatomic number50which means there are 50 protons and 50 electrons in the atomic structure. Thechemical symbolfor Tin isSn.

Tin is a post-transition metal in group 14 of the periodic table. It is obtained chiefly from the mineral cassiterite, which contains tin dioxide. The first alloy used on a large scale was bronze, made of tin and copper, from as early as 3000 BC.

Discoverer: unknown

Element Category: Metalloids

Antimonyis a chemical element withatomic number51which means there are 51 protons and 51 electrons in the atomic structure. Thechemical symbolfor Antimony isSb.

Antimony is a lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite. Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name, kohl.

Discoverer: Müller von Reichenstein, Franz Joseph

Element Category: Metalloids

Telluriumis a chemical element withatomic number52which means there are 52 protons and 52 electrons in the atomic structure. Thechemical symbolfor Tellurium isTe.

Tellurium is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur. It is occasionally found in native form as elemental crystals. Tellurium is far more common in the universe as a whole than on Earth. Its extreme rarity in the Earth’s crust, comparable to that of platinum.

Discoverer: Courtois, Bernard

Element Category: Nonmetal

Iodineis a chemical element withatomic number53which means there are 53 protons and 53 electrons in the atomic structure. Thechemical symbolfor Iodine isI.

Iodine is the heaviest of the stable halogens, it exists as a lustrous, purple-black metallic solid at standard conditions that sublimes readily to form a violet gas. Iodine is the least abundant of the stable halogens, being the sixty-first most abundant element. It is even less abundant than the so-called rare earths. It is the heaviest essential mineral nutrient.

Discoverer: Ramsay, William and Travers, Morris William

Element Category: Noble gas

Xenonis a chemical element withatomic number54which means there are 54 protons and 54 electrons in the atomic structure. Thechemical symbolfor Xenon isXe.

Xenon is a colorless, dense, odorless noble gas found in the Earth’s atmosphere in trace amounts. The name xenon for this gas comes from the Greek word ξένον [xenon], neuter singular form of ξένος [xenos], meaning ‘foreign(er)’, ‘strange(r)’, or ‘guest’. In nuclear industry, especially artificial xenon 135 has a tremendous impact on the operation of a nuclear reactor.

Discoverer: Kirchhoff, Gustav and Bunsen, Robert

Element Category: Alkali metal

Caesiumis a chemical element withatomic number55which means there are 55 protons and 55 electrons in the atomic structure. Thechemical symbolfor Caesium isCs.

Caesium is a soft, silvery-gold alkali metal with a melting point of 28.5 °C, which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium has physical and chemical properties similar to those of rubidium and potassium.

Discoverer: Davy, Sir Humphry

Element Category: Alkaline earth metals

Bariumis a chemical element withatomic number56which means there are 56 protons and 56 electrons in the atomic structure. Thechemical symbolfor Barium isBa.

Barium is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. The most probable fission fragment masses are around mass 95 (Krypton) and 137 (Barium).

Lanthanoids

Discoverer: —

Element Category:

Discoverer: Coster, Dirk and De Hevesy, George Charles

Element Category: Transition metals

Discoverer: Ekeberg, Anders Gustav

Element Category: Transition metals

Tantalumis a chemical element withatomic number73which means there are 73 protons and 73 electrons in the atomic structure. Thechemical symbolfor Tantalum isTa.

Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion-resistant.

Discoverer: Elhuyar, Juan José and Elhuyar, Fausto

Element Category: Transition metals

Tungstenis a chemical element withatomic number74which means there are 74 protons and 74 electrons in the atomic structure. Thechemical symbolfor Tungsten isW.

Tungsten is a rare metal found naturally on Earth almost exclusively in chemical compounds. Tungsten is an intrinsically brittle and hard material, making it difficult to work.

Discoverer: Noddack, Walter and Berg, Otto Carl and Tacke, Ida

Element Category: Transition metals

Rheniumis a chemical element withatomic number75which means there are 75 protons and 75 electrons in the atomic structure. Thechemical symbolfor Rhenium isRe.

Rhenium is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table.

Discoverer: Tennant, Smithson

Element Category: Transition metals

Discoverer: Tennant, Smithson

Element Category: Transition metals

Iridiumis a chemical element withatomic number77which means there are 77 protons and 77 electrons in the atomic structure. Thechemical symbolfor Iridium isIr.

Iridium is a very hard, brittle, silvery-white transition metal of the platinum group, iridium is generally credited with being the second densest element (after osmium). It is also the most corrosion-resistant metal, even at temperatures as high as 2000 °C.

Discoverer: Ulloa, Antonio de

Element Category: Transition metals

Discoverer: unknown

Element Category: Transition metals

Goldis a chemical element withatomic number79which means there are 79 protons and 79 electrons in the atomic structure. Thechemical symbolfor Gold isAu.

Gold is a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal. Gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions. Gold is thought to have been produced in supernova nucleosynthesis, from the collision of neutron stars.

Discoverer: unknown

Element Category: Transition metals

Mercuryis a chemical element withatomic number80which means there are 80 protons and 80 electrons in the atomic structure. Thechemical symbolfor Mercury isHg.

Mercury is commonly known as quicksilver and was formerly named hydrargyrum. Mercury is a heavy, silvery d-block element, mercury is the only metallic element that is liquid at standard conditions for temperature and pressure.

Discoverer: Crookes, William

Element Category: Post-transition metals

Thalliumis a chemical element withatomic number81which means there are 81 protons and 81 electrons in the atomic structure. Thechemical symbolfor Thallium isTl.

Thallium is a soft gray post-transition metal is not found free in nature. Commercially, thallium is produced as a byproduct from refining of heavy metal sulfide ores. Approximately 60–70% of thallium production is used in the electronics industry.

Discoverer: unknown

Element Category: Post-transition metals

Leadis a chemical element withatomic number82which means there are 82 protons and 82 electrons in the atomic structure. Thechemical symbolfor Lead isPb.

Lead is a heavy metal that is denser than most common materials. Lead is soft and malleable, and has a relatively low melting point. Lead is widely used as a gamma shield. Major advantage of lead shield is in its compactness due to its higher density. Lead has the highest atomic number of any stable element and concludes three major decay chains of heavier elements.

Discoverer: Geoffroy, Claude

Element Category: Post-transition metals

Bismuthis a chemical element withatomic number83which means there are 83 protons and 83 electrons in the atomic structure. Thechemical symbolfor Bismuth isBi.

Bismuth is a brittle metal with a silvery white color when freshly produced, but surface oxidation can give it a pink tinge. Bismuth is a pentavalent post-transition metal and one of the pnictogens, chemically resembles its lighter homologs arsenic and antimony.

Discoverer: Curie, Marie and Pierre

Element Category: Post-transition metals

Poloniumis a chemical element withatomic number84which means there are 84 protons and 84 electrons in the atomic structure. Thechemical symbolfor Polonium isPo.

Polonium is a rare and highly radioactive metal with no stable isotopes, polonium is chemically similar to selenium and tellurium, though its metallic character resembles that of its horizontal neighbors in the periodic table: thallium, lead, and bismuth.

Discoverer: Corson, Dale R. and Mackenzie, K. R.

Element Category: Metalloids

Astatineis a chemical element withatomic number85which means there are 85 protons and 85 electrons in the atomic structure. Thechemical symbolfor Astatine isAt.

Astatine is the rarest naturally occurring element on the Earth’s crust. It occurs on Earth as the decay product of various heavier elements. The bulk properties of astatine are not known with any certainty.

Discoverer: Dorn, Friedrich Ernst

Element Category: Noble gas

Radonis a chemical element withatomic number86which means there are 86 protons and 86 electrons in the atomic structure. Thechemical symbolfor Radon isRn.

Radon is a radioactive, colorless, odorless, tasteless noble gas. Radon occurs naturally as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead.

Discoverer: Perey, Marguerite

Element Category: Alkali metal

Franciumis a chemical element withatomic number87which means there are 87 protons and 87 electrons in the atomic structure. Thechemical symbolfor Francium isFr.

Francium is an alkali metal, that has one valence electron. Francium is the second-least electronegative element, behind only caesium, and is the second rarest naturally occurring element (after astatine). Francium is a highly radioactive metal that decays into astatine, radium, and radon.

Discoverer: Curie, Marie and Pierre

Element Category: Alkaline earth metal

Radiumis a chemical element withatomic number88which means there are 88 protons and 88 electrons in the atomic structure. Thechemical symbolfor Radium isRa.

Pure radium is silvery-white alkaline earth metal. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226.

Actinoids

The actinide or actinoid series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.

Discoverer: Scientists at Dubna, Russia (1964)/Albert Ghiorso et. al. (1969)

Element Category: Transition metal

Discoverer: Scientists at Dubna, Russia (1967)/Lawrence Berkeley Laboratory (1970)

Element Category: Transition metal

Discoverer: Albert Ghiorso et. al.

Element Category: Transition metal

Discoverer: Scientists at Dubna, Russia

Element Category: Transition metal

Discoverer: Armbruster, Paula and Muenzenberg, Dr. Gottfried

Element Category: Transition metal

Discoverer: Armbruster, Paula and Muenzenberg, Dr. Gottfried

Element Category: unknown, probably a transition metal

Discoverer: Armbruster, Paula and Muenzenberg, Dr. Gottfried

Element Category: unknown, probably a transition metal

Discoverer: David Anderson, Ruhani Rabin, Team Updraft

Element Category: unknown, probably a transition metal

Discoverer: Armbruster, Paula and Muenzenberg, Dr. Gottfried

Element Category: unknown, probably a transition metal

Discoverer: Y. T. Oganessian et. al.

Element Category: unknown, probably a transition metal

Discoverer: Scientists at Dubna, Russia

Element Category: unknown, probably a post-transition metal

Discoverer: Y. T. Oganessian et. al.

Element Category: unknown

Discoverer: Scientists at Dubna, Russia

Element Category: unknown

Discoverer: —

Element Category: unknown

Discoverer: Y. T. Oganessian et. al.

Element Category: unknown

Discoverer: Mosander, Carl Gustav

Element Category: Lanthanoids

Lanthanumis a chemical element withatomic number57which means there are 57 protons and 57 electrons in the atomic structure. Thechemical symbolfor Lanthanum isLa.

Lanthanum is a soft, ductile, silvery-white metal that tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. It is also sometimes considered the first element of the 6th-period transition metals and is traditionally counted among the rare earth elements.

Discoverer: Hisinger, Wilhelm and Berzelius, Jöns Jacob/Klaproth, Martin Heinrich

Element Category: Lanthanoids

Ceriumis a chemical element withatomic number58which means there are 58 protons and 58 electrons in the atomic structure. Thechemical symbolfor Cerium isCe.

Cerium is a soft, ductile and silvery-white metal that tarnishes when exposed to air, and it is soft enough to be cut with a knife. Cerium is the second element in the lanthanide series. Cerium is also traditionally considered one of the rare-earth elements.

Discoverer: Von Welsbach, Baron Auer

Element Category: Lanthanoids

Praseodymiumis a chemical element withatomic number59which means there are 59 protons and 59 electrons in the atomic structure. Thechemical symbolfor Praseodymium isPr.

Praseodymium is a soft, silvery, malleable and ductile metal, valued for its magnetic, electrical, chemical, and optical properties. Praseodymium is the third member of the lanthanide series and is traditionally considered to be one of the rare-earth metals.

Discoverer: Von Welsbach, Baron Auer

Element Category: Lanthanoids

Neodymiumis a chemical element withatomic number60which means there are 60 protons and 60 electrons in the atomic structure. Thechemical symbolfor Neodymium isNd.

Neodymium is a soft silvery metal that tarnishes in air. Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Although neodymium is classed as a rare earth, it is a fairly common element.

Discoverer: Marinsky, Jacob A. and Coryell, Charles D. and Glendenin, Lawerence. E.

Element Category: Lanthanoids

Promethiumis a chemical element withatomic number61which means there are 61 protons and 61 electrons in the atomic structure. Thechemical symbolfor Promethium isPm.

Promethium is one of only two such elements that are followed in the periodic table by elements with stable forms. All of its isotopes are radioactive. In nuclear reactors, promethium equilibrium exists in power operation. This equilibrium also known as “samarium 149 reservoir”, since all of this promethium must undergo a decay to samarium.

Discoverer: Lecoq de Boisbaudran, Paul-Émile

Element Category: Lanthanoids

Discoverer: Demarçay, Eugène-Antole

Element Category: Lanthanoids

Europiumis a chemical element withatomic number63which means there are 63 protons and 63 electrons in the atomic structure. Thechemical symbolfor Europium isEu.

Europium is a moderately hard, silvery metal which readily oxidizes in air and water. Being a typical member of the lanthanide series, europium usually assumes the oxidation state +3. Europium is one of the least abundant elements in the universe. Only about 5×10−8% of all matter in the universe is europium.

Discoverer: De Marignac, Charles Galissard

Element Category: Lanthanoids

Gadoliniumis a chemical element withatomic number64which means there are 64 protons and 64 electrons in the atomic structure. Thechemical symbolfor Gadolinium isGd.

Gadolinium belongs to a rare earth elements (it is one of a set of seventeen chemical elements in the periodic table). In nuclear industry gadolinium is commonly used as a neutron absorber due to very high neutron absorbtion cross-section of two isotopes 155Gd and 157Gd. In fact their absorption cross-sections are the highest among all stable isotopes.

Discoverer: Mosander, Carl Gustav

Element Category: Lanthanoids

Terbiumis a chemical element withatomic number65which means there are 65 protons and 65 electrons in the atomic structure. Thechemical symbolfor Terbium isTb.

Terbium is a silvery-white, rare earth metal that is malleable, ductile, and soft enough to be cut with a knife. The ninth member of the lanthanide series, terbium is a fairly electropositive metal that reacts with water, evolving hydrogen gas.

Discoverer: Lecoq de Boisbaudran, Paul-Émile

Element Category: Lanthanoids

Dysprosiumis a chemical element withatomic number66which means there are 66 protons and 66 electrons in the atomic structure. Thechemical symbolfor Dysprosium isDy.

is a rare earth element with a metallic silver luster. Dysprosium is used for its high thermal neutron absorption cross-section in making control rods in nuclear reactors, for its high magnetic susceptibility in data storage applications.

Discoverer: Cleve, Per Theodor

Element Category: Lanthanoids

Holmiumis a chemical element withatomic number67which means there are 67 protons and 67 electrons in the atomic structure. Thechemical symbolfor Holmium isHo.

Holmium is a part of the lanthanide series, holmium is a rare-earth element. Holmium is a relatively soft and malleable silvery-white metal.

Discoverer: Mosander, Carl Gustav

Element Category: Lanthanoids

Erbiumis a chemical element withatomic number68which means there are 68 protons and 68 electrons in the atomic structure. Thechemical symbolfor Erbium isEr.

Erbium is a silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements. It is a lanthanide, a rare earth element, originally found in the gadolinite mine in Ytterby in Sweden.

Discoverer: Cleve, Per Teodor

Element Category: Lanthanoids

Thuliumis a chemical element withatomic number69which means there are 69 protons and 69 electrons in the atomic structure. Thechemical symbolfor Thulium isTm.

Thulium is an easily workable metal with a bright silvery-gray luster. It is fairly soft and slowly tarnishes in air. Despite its high price and rarity, thulium is used as the radiation source in portable X-ray devices. Thulium is the thirteenth and third-last element in the lanthanide series.

Discoverer: De Marignac, Jean Charles Galissard

Element Category: Lanthanoids

Ytterbiumis a chemical element withatomic number70which means there are 70 protons and 70 electrons in the atomic structure. Thechemical symbolfor Ytterbium isYb.

Because of its closed-shell electron configuration, its density and melting and boiling points differ significantly from those of most other lanthanides.

Discoverer: Urbain, Georges

Element Category: Lanthanoids

Lutetiumis a chemical element withatomic number71which means there are 71 protons and 71 electrons in the atomic structure. Thechemical symbolfor Lutetium isLu.

Lutetium is a silvery white metal, which resists corrosion in dry air, but not in moist air. Lutetium is the last element in the lanthanide series, and it is traditionally counted among the rare earths.

Discoverer: Debierne, André

Element Category: Actinoids

Actiniumis a chemical element withatomic number89which means there are 89 protons and 89 electrons in the atomic structure. Thechemical symbolfor Actinium isAc.

Actinium is a soft, silvery-white radioactive metal. Actinium gave the name to the actinide series, a group of 15 similar elements between actinium and lawrencium in the periodic table.

Discoverer: Berzelius, Jöns Jacob

Element Category: Actinoids

Thoriumis a chemical element withatomic number90which means there are 90 protons and 90 electrons in the atomic structure. Thechemical symbolfor Thorium isTh.

Thorium metal is silvery and tarnishes black when exposed to air, forming the dioxide. Thorium is moderately hard, malleable, and has a high melting point. Thorium is a naturally-occurring element and it is estimated to be about three times more abundant than uranium. Thorium is commonly found in monazite sands (rare earth metals containing phosphate mineral).

Discoverer: Göhring, Otto and Fajans, Kasimir

Element Category: Actinoids

Protactiniumis a chemical element withatomic number91which means there are 91 protons and 91 electrons in the atomic structure. Thechemical symbolfor Protactinium isPa.

Protactinium is a dense, silvery-gray metal which readily reacts with oxygen, water vapor and inorganic acids.

Discoverer: Klaproth, Martin Heinrich

Element Category: Actinoids

Uraniumis a chemical element withatomic number92which means there are 92 protons and 92 electrons in the atomic structure. Thechemical symbolfor Uranium isU.

Uranium is a silvery-white metal in the actinide series of the periodic table. Uranium is weakly radioactive because all isotopes of uranium are unstable, with half-lives varying between 159,200 years and 4.5 billion years. Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten.

Discoverer: McMillan, Edwin M. and Abelson, Philip H.

Element Category: Actinoids

Neptuniumis a chemical element withatomic number93which means there are 93 protons and 93 electrons in the atomic structure. Thechemical symbolfor Neptunium isNp.

Neptunium metal is silvery and tarnishes when exposed to air. Neptunium is the first transuranic element.

Discoverer: Glenn T. Seaborg, Joseph W. Kennedy, Edward M. McMillan, Arthur C. Wohl

Element Category: Actinoids

Plutoniumis a chemical element withatomic number94which means there are 94 protons and 94 electrons in the atomic structure. Thechemical symbolfor Plutonium isPu.

Plutonium is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized.

Discoverer: Glenn T. Seaborg, Ralph A. James, Leon O. Morgan, Albert Ghiorso

Element Category: Actinoids

Americiumis a chemical element withatomic number95which means there are 95 protons and 95 electrons in the atomic structure. Thechemical symbolfor Americium isAm.

Americium is a transuranic member of the actinide series, in the periodic table located under the lanthanide element europium, and thus by analogy was named after the Americas.

Discoverer: Glenn T. Seaborg, Ralph A. James, Albert Ghiorso

Element Category: Actinoids

Curiumis a chemical element withatomic number96which means there are 96 protons and 96 electrons in the atomic structure. Thechemical symbolfor Curium isCm.

Curium is a hard, dense, silvery metal with a relatively high melting point and boiling point for an actinide.

Discoverer: Stanley G. Thompson, Glenn T. Seaborg, Kenneth Street, Jr., Albert Ghiorso

Element Category: Actinoids

Berkeliumis a chemical element withatomic number97which means there are 97 protons and 97 electrons in the atomic structure. Thechemical symbolfor Berkelium isBk.

Berkelium is a member of the actinide and transuranium element series.

Discoverer: Stanley G. Thompson, Glenn T. Seaborg, Kenneth Street, Jr., Albert Ghiorso

Element Category: Actinoids

Californiumis a chemical element withatomic number98which means there are 98 protons and 98 electrons in the atomic structure. Thechemical symbolfor Californium isCf.

Californium is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all the elements that have been produced in amounts large enough to see with the unaided eye (after einsteinium). The most commonly used spontaneous fission neutron source is the radioactive isotope californium-252.

Discoverer: Albert Ghiorso et. al.

Element Category: Actinoids

Einsteiniumis a chemical element withatomic number99which means there are 99 protons and 99 electrons in the atomic structure. Thechemical symbolfor Einsteinium isEs.

Einsteinium is the seventh transuranic element, and an actinide.

Discoverer: Albert Ghiorso et. al.

Element Category: Actinoids

Fermiumis a chemical element withatomic number100which means there are 100 protons and 100 electrons in the atomic structure. Thechemical symbolfor Fermium isFm.

Fermium is a member of the actinide series. It is the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities.

Discoverer: Stanley G. Thompson, Glenn T. Seaborg, Bernard G. Harvey, Gregory R. Choppin, Albert Ghiorso

Element Category: Actinoids

Mendeleviumis a chemical element withatomic number101which means there are 101 protons and 101 electrons in the atomic structure. Thechemical symbolfor Mendelevium isMd.

Mendelevium is a metallic radioactive transuranic element in the actinide series, it is the first element that currently cannot be produced in macroscopic quantities.

Discoverer: Albert Ghiorso, Glenn T. Seaborg, Torbørn Sikkeland, John R. Walton

Element Category: Actinoids

Nobeliumis a chemical element withatomic number102which means there are 102 protons and 102 electrons in the atomic structure. Thechemical symbolfor Nobelium isNo.

Nobelium is the tenth transuranic element and is the penultimate member of the actinide series. Like all elements with atomic number over 100, nobelium can only be produced in particle accelerators by bombarding lighter elements with charged particles.

Discoverer: Albert Ghiorso, Torbjørn Sikkeland, Almon E. Larsh, Robert M. Latimer

Element Category: Actinoids

Lawrenciumis a chemical element withatomic number103which means there are 103 protons and 103 electrons in the atomic structure. Thechemical symbolfor Lawrencium isLr.

Lawrencium is the final member of the actinide series. Like all elements with atomic number over 100, lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles.