Periodic Table of the Elements

1 Hydrogen

The lightest and most abundant chemical element, constituting roughly 75 % of the Universe's chemical elemental mass. Stars in the main sequence are mainly composed of hydrogen in its plasma state. Naturally occurring elemental hydrogen is relatively rare on Earth.


2 Helium

It is a colorless, odorless, tasteless, non-toxic, inert monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among the elements and it exists only as a gas except in extreme conditions. Next to hydrogen, it is the second most abundant element in the universe, and accounts for 24% of the elemental mass of our galaxy.


3 Lithium

Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly reactive and flammable. For this reason, it is typically stored in mineral oil. When cut open, lithium exhibits a metallic luster, but contact with moist air corrodes the surface quickly to a dull silvery gray, then black, tarnish. Because of its high reactivity, lithium never occurs free in nature, and instead, only appears in compounds, usually ionic ones.


4 Beryllium

A divalent element, beryllium is found naturally only combined with other elements in minerals. Notable gemstones which contain beryllium include beryl (aquamarine, emerald) and chrysoberyl. The free element is a steel-gray, strong, lightweight brittle alkaline earth metal. It is primarily used as a hardening agent in alloys, notably beryllium copper. It has been used in rocket nozzles and is a significant component of planned space telescopes.


5 Boron

A low-abundance element in both the solar system and the Earth's crust, boron is concentrated on Earth by the water-solubility of its more common naturally-occurring compounds, the borate minerals. These are mined industrially as evaporate ores, such as borax and kernite.


6 Carbon

As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of about 5730 years.[9] Carbon is one of the few elements known since antiquity.[10][11] The name "carbon" comes from Latin language carbo, coal.


7 Nitrogen

Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere. The extremely strong bond in elemental nitrogen dominates nitrogen chemistry, causing difficulty for both organisms and industry in breaking the bond to convert the N2 into useful compounds, but at the same time causing release of large amounts of often useful energy when the compounds burn, explode, or decay back into nitrogen gas. Nitrogen occurs in all living organisms, and the nitrogen cycle describes movement of the element from air into the biosphere and organic compounds, then back into the atmosphere.


8 Oxygen

Oxygen is a member of the chalcogen group on the periodic table, and is a highly reactive nonmetallic period 2 element that readily forms compounds (notably oxides) with almost all other elements. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless, odorless, tasteless diatomic gas with the formula O2. By mass, oxygen is the third most abundant element in the universe after hydrogen and helium and the most abundant element by mass in the Earth's crust. Diatomic oxygen gas constitutes 20.8% of the volume of air.

All major classes of structural molecules in living organisms, such as proteins, carbohydrates, and fats, contain oxygen, as do the major inorganic compounds that comprise animal shells, teeth, and bone. Oxygen in the form of O2 is produced from water by cyanobacteria, algae and plants during photosynthesis and is used in cellular respiration for all complex life. Oxygen is toxic to obligately anaerobic organisms.


9 Flourine

Fluorine forms a single bond with itself in elemental form, resulting in the diatomic F2 molecule. F2 (fluorine) is a supremely reactive, poisonous, pale, yellowish brown gas. Elemental fluorine is the most chemically reactive and electronegative of all the elements. For example, it will readily "burn" hydrocarbons at room temperature, in contrast to the combustion of hydrocarbons by oxygen, which requires an input of energy with a spark. Therefore, molecular fluorine is highly dangerous, more so than other halogens such as the poisonous chlorine gas.


10 Neon

Although a very common element in the universe, it is rare on Earth. A colorless, inert noble gas under standard conditions, neon gives a distinct reddish-orange glow when used in discharge tubes and neon lamps and advertising signs. It is commercially extracted from air, in which it is found in trace amounts.


11 Sodium

It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals within "group 1". It has only one stable isotope, 23Na. Sodium is an essential element for all animal life (including human) and for some plant species. In animals, sodium ions are used in opposition to potassium ions, to allow the organism to build up an electrostatic charge on cell membranes, and thus allow transmission of nerve impulses when the charge is allowed to dissipate by a moving wave of voltage change.


12 Magnesium

It is an alkaline earth metal and the eighth most abundant element in the Earth's crust, where it constitutes about 2% by mass, and ninth in the known Universe as a whole. This preponderance of magnesium is related to the fact that it is easily built up in supernova stars from a sequential addition of three helium nuclei to carbon (which in turn is made from three helium nuclei). Magnesium ion's high solubility in water helps ensure that it is the third most abundant element dissolved in seawater.


13 Aluminium

It is not soluble in water under normal circumstances. Aluminium is the most abundant metal in the Earth's crust, and the third most abundant element, after oxygen and silicon. It makes up about 8% by weight of the Earth's solid surface. Aluminium is too reactive chemically to occur in nature as a free metal. Instead, it is found combined in over 270 different minerals.


14 Silicon

A tetravalent metalloid, silicon is less reactive than its chemical analog carbon. Silicon is the eighth most common element in the universe by mass, but silicon very rarely occurs as the pure free element in nature. It is more widely distributed in dusts, sands, planetoids and planets as various forms of silicon dioxide (silica) or silicates. In Earth's crust, silicon is the second most abundant element after oxygen, making up 27.7% of the crust by mass.


15 Phosphorus

A multivalent nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate rocks. Elemental phosphorus exists in two major forms – white phosphorus and red phosphorus. Although the term "phosphorescence", meaning glow after illumination, derives from phosphorus, the glow of phosphorus originates from oxidation of the white (but not red) phosphorus and should be called chemiluminescence. Due to its high reactivity, phosphorus is never found as a free element in nature on Earth. Phosphorus is a component of DNA, RNA, ATP, and also the phospholipids that form all cell membranes. It is, thus, an essential element for all living cells. The most important commercial use of phosphorus-based chemicals is the production of fertilizers.


16 Sulfur

It is an abundant, multivalent non-metal. Sulfur, in its native form, is a bright yellow crystalline solid. In nature, it can be found as the pure element and as sulfide and sulfate minerals. It is an essential element for life and is found in two amino acids: cysteine and methionine. Its commercial uses are primarily in fertilizers, but it is also widely used in black gunpowder, matches, insecticides and fungicides. Elemental sulfur crystals are commonly sought after by mineral collectors for their brightly colored polyhedron shapes.


17 Chlorine

It is a halogen, found in the periodic table in group 17. As the chloride ion, which is part of common salt and other compounds, it is abundant in nature and necessary to most forms of life, including humans. In its elemental form (Cl2 or "dichlorine") under standard conditions, chlorine is a powerful oxidant and is used in bleaching and disinfectants, as well as an essential reagent in the chemical industry.


18 Argon

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.


19 Potassium

Elemental potassium is a soft silvery-white metallic alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction. Potassium and sodium are alkali metals and are chemically very similar.


20 Calcium

Calcium is a soft gray alkaline earth metal, and is the fifth most abundant element by mass in the Earth's crust. Calcium is also the fifth most abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate. Calcium is essential for living organisms, particularly in cell physiology, where movement of the calcium ion Ca2+ into and out of the cytoplasm functions as a signal for many cellular processes. As a major material used in mineralization of bones and shells, calcium is the most abundant metal by mass in many animals.


21 Scandium

Scandium is present in most of the rare earth element and uranium deposits, but it is extracted from these ores in only a few mines worldwide. Scandium metal is hard and has a silvery appearance. It develops a slightly yellowish or pinkish cast when exposed to air.


22 Titanium

Sometimes called the "space age metal", it has a low density and is a strong, lustrous, corrosion-resistant (including sea water, aqua regia and chlorine) transition metal with a silver color. The element occurs within a number of mineral deposits, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere, and it is found in almost all living things, rocks, water bodies, and soils.


23 Vanadium

It is a soft, silvery gray, ductile transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature. Large amounts of vanadium ions are found in a few organisms, possibly as a toxin. The oxide and some other salts of vanadium have moderate toxicity.


24 Chromium

It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable. The name of the element is derived from the Greek word "chrōma", meaning color, because many of its compounds are intensely colored. Chromium was regarded with great interest because of its high corrosion resistance and hardness.


25 Manganese

It is found as a free element in nature (often in combination with iron), and in many minerals. As a free element, manganese is a metal with important industrial metal alloy uses, particularly in stainless steels.


26 Iron

It is the most common element in the whole planet Earth, forming much of Earth's outer and inner core, and it is the fourth most common element in the Earth's crust. It is produced in abundance as a result of fusion in high-mass stars, where the production of nickel-56 (which decays to iron) is the last nuclear fusion reaction that is exothermic, becoming the last element to be produced before collapse of a supernova leads to events that scatter the precursor radionuclides of iron into space.


27 Cobalt

It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal. Cobalt is an essential trace element for all animal organisms, as the active center of coenzymes called cobalamins. These include vitamin B12 which is essential for mammals. Cobalt is also an active nutrient for bacteria, algae, and fungi.


28 Nickel

It is a silvery-white lustrous metal with a slight golden tinge. It is one of the four elements that are ferromagnetic around room temperature, the other three being iron, cobalt and gadolinium.


29 Copper

t is a ductile metal, with very high thermal and electrical conductivity. Pure copper is rather soft and malleable, and a freshly exposed surface has a reddish-orange color. It is used as a thermal conductor, an electrical conductor, a building material, and a constituent of various metal alloys.


30 Zinc

Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2. Zinc is the 24th most abundant element in the Earth's crust and has five stable isotopes. Zinc is an essential mineral of "exceptional biologic and public health importance". Zinc deficiency affects about two billion people in the developing world and is associated with many diseases.


31 Gallium

Elemental gallium does not occur in nature, but as the gallium(III) salt in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal, elemental gallium is a brittle solid at low temperatures. As it liquefies slightly above room temperature, it will melt in the hand.


32 Germanium

It is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. Germanium has five naturally occurring isotopes ranging in atomic mass number from 70 to 76. It forms a large number of organometallic compounds, including tetraethylgermane and isobutylgermane.s


33 Arsenic

Arsenic occurs in many minerals, mainly combined with sulfur and metals, and also naturally in the native (elemental) state. The main use of metallic arsenic is for strengthening alloys of copper and especially lead (for example, in automotive batteries). Arsenic is notoriously poisonous to multicellular life, due to the interaction of arsenic ions with protein thiols. A NASA-funded astrobiology research team reported that the microbe strain Gammaproteobacteria group has the ability to substitute arsenic for at least part of the phosphorus in the molecules of its cells, including DNA and ATP.


34 Selenium

It is a nonmetal, chemically related to sulfur and tellurium, and rarely occurs in its elemental state in nature. Selenium salts are toxic in large amounts. It conducts electricity better in the light than in the dark, and is used in photocells.


35 Bromine

Elemental bromine is a fuming red-brown liquid at room temperature, corrosive and toxic, with properties between those of chlorine and iodine. Free bromine does not occur in nature, but occurs as colorless soluble crystalline mineral halide salts, analogous to table salt. Bromine is rarer than about three-quarters of elements in the Earth's crust, however the high solubility of bromide ion has caused its accumulation in the oceans, and commercially the element is easily extracted from brine pools.


36 Krypton

A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere, is isolated by fractionally distilling liquified air, and is often used with other rare gases in fluorescent lamps. Krypton is inert for most practical purposes. Krypton can also form clathrates with water when atoms of it are trapped in a lattice of the water molecules.


37 Rubidium

Rubidium is a soft, silvery-white metallic element of the alkali metal group. Elemental rubidium is very soft and highly reactive, with properties similar to other elements in group 1, such as very rapid oxidation in air. Its compounds have chemical and electronic applications. Rubidium metal is easily vaporized and has a convenient spectral absorption range, making it a frequent target for laser manipulation of atoms.


38 Strontium

An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when exposed to air. It occurs naturally in the minerals celestine and strontianite.


39 Yttrium

It is a silvery-metallic transition metal chemically similar to the lanthanoids and has historically been classified as a rare earth element. Yttrium is almost always found combined with the lanthanoids in rare earth minerals and is never found in nature as a free element.


40 Zirconium

t is a lustrous, grey-white, strong transition metal that resembles titanium. Zirconium is used as an alloying agent for its strong resistance to corrosion. It is never found as a native metal; it is obtained mainly from the mineral zircon, which can be purified with chlorine.


41 Niobium

A rare, soft, grey, ductile transition metal, niobium is found in the minerals pyrochlore, the main commercial source for niobium, and columbite.


42 Molybdenum

The free element, which is a silvery metal, has the sixth-highest melting point of any element. It readily forms hard, stable carbides, and for this reason it is often used in high-strength steel alloys. Molybdenum does not occur as the free metal in nature, but rather in various oxidation states in minerals.


43 Technetium

It is the lowest atomic number element without any stable isotopes; every form of it is radioactive. Nearly all technetium is produced synthetically and only minute amounts are found in nature. It's been found to be naturally occurring deep within stars in nuclear fusion, where it then slowly comes to the surface (how it's been detected).


44 Ruthenium

It is a rare transition metal of the platinum group of the periodic table; and like the other metals of the platinum group, ruthenium is inert to most other chemicals. Ruthenium is found associated with platinum ores. Ruthenium is a minor component in these ores and therefore is a relatively rare element.


45 Rhodium

Naturally-occurring rhodium is composed of only one isotope, 103Rh. It is one of the rarest precious metals. Rhodium is inert against corrosion and most aggressive chemicals.


46 Palladium

Palladium is a rare and lustrous silvery-white metal. Platinum group metals share similar chemical properties, but palladium has the lowest melting point and is the least dense of these precious metals.


47 Silver

A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal. The metal occurs naturally in its pure, free form.


48 Cadmium

The soft, bluish-white metal is chemically similar to the two other metals in group 12, zinc and mercury. Average concentration in the earth's crust is between 0.1 and 0.5 parts per million (ppm).


49 Indium

This rare, very soft, malleable and easily fusible post-transition metal is chemically similar to aluminium. Indium is not known to be used by any organism.


50 Tin

This silvery, malleable poor metal is not easily oxidized in air and is used to coat other metals to prevent corrosion. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and +4, with the +4 state being slightly more stable than the 2+ state. Tin is the 49th most abundant element and has, with 10 stable isotopes, the largest number of stable isotopes in the periodic table.


51 Antimony

A silvery lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite. Antimony compounds are prominent fire retardants found in many commercial and domestic products. Certain alloys are valuable for use in solders and ball bearings. An emerging application is the use of antimony in microelectronics. The relatively high toxicity of some antimony compounds, being similar to arsenic compounds, limits the applications.


52 Tellurium

A brittle, mildly toxic, silver-white metalloid which looks similar to tin, tellurium is chemically related to selenium and sulfur. Tellurium has no biological function, although fungi can incorporate it in place of sulfur and selenium into amino acids.


53 Iodine

Iodine and its compounds are primarily used in nutrition, the production of acetic acid and polymers. Iodine's relatively high atomic number, low toxicity, and ease of attachment to organic compounds have made it a part of many X-ray contrast materials in modern medicine.


54 Xenon

A colorless, heavy, odorless noble gas, xenon occurs in the Earth's atmosphere in trace amounts. Although generally unreactive, xenon can undergo a few chemical reactions. Naturally occurring xenon consists of nine stable isotopes.


55 Caesium

It is a soft, silvery-gold alkali metal with a melting point of 28 °C, which makes it one of only five elemental metals that are liquid at (or near) room temperature. Caesium is an alkali metal and has physical and chemical properties similar to those of rubidium and potassium. The metal is extremely reactive and pyrophoric, reacting with water even at −116 °C .


56 Barium

It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with water and carbon dioxide and is not found as a mineral. The most common naturally occurring minerals are the very insoluble barium sulfate.


71 Lutetium

Lutetium is a silvery white corrosion-resistant trivalent metal. It has the smallest atomic radius and is the heaviest and hardest of the rare earth elements. Lutetium has the highest melting point of any lanthanide, probably related to the lanthanide contraction.


72 Hafnium

A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Hafnium is used in filaments and electrodes.


73 Tantalum

A rare, hard, blue-gray, lustrous transition metal, tantalum is highly corrosion resistant and occurs naturally in the mineral tantalite, always together with the chemically similar niobium. It is part of the refractory metals group, which are widely used as minor component in alloys. The chemical inertness of tantalum makes it a valuable substance for laboratory equipment and a substitute for platinum, but its main use today is in tantalum capacitors in electronic equipment.


74 Tungsten

A steel-gray metal under standard conditions when uncombined, tungsten is found naturally on Earth only combined in chemical compounds. The free element is remarkable for its robust physical properties, especially the fact that it has the highest melting point of all the non-alloyed metals and the second highest of all the elements after carbon. Also remarkable is its very high density of 19.3 times that of water. This density is slightly more than that of uranium and 71% more than that of lead. Tungsten with minor amounts of impurities is often brittle and hard, making it difficult to work.


75 Rhenium

It is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. With an average concentration of 1 part per billion, rhenium is one of the rarest elements in the Earth's crust. The free element has the third-highest melting point of any element, exceeded only by tungsten and carbon.


76 Osmium

Osmium is a hard, brittle, blue-gray or blue-black transition metal in the platinum family, and is the densest natural element. Osmium is twice as dense as lead. The density of osmium is 22.59 g/cm3, slightly greater than that of iridium, the second densest element. Osmium is found in nature as an alloy, mostly in platinum ores. Osmium is also used in alloys, with platinum, iridium and other platinum group metals. Those alloys are employed in fountain pen tips, electrical contacts and in other applications where extreme durability and hardness are needed.


77 Iridium

A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second densest element (after osmium) and is the most corrosion-resistant metal, even at temperatures as high as 2000°C. Although only certain molten salts and halogens are corrosive to solid iridium, finely divided iridium dust is much more reactive and can be flammable.


78 Platinum

It is a dense, malleable, ductile, precious, gray-white transition metal. Even though it has six naturally occurring isotopes, platinum is one of the rarest elements in the Earth's crust and has an average abundance of approximately 0.005 mg/kg. It exhibits a remarkable resistance to corrosion, even at high temperatures, and as such is considered a noble metal. As a result, platinum is often found chemically uncombined as native platinum. It does not oxidize at any temperature, although it is corroded by halogens, cyanides, sulfur, and caustic alkalis. Platinum is insoluble in hydrochloric and nitric acid.


79 Gold

Gold metal is dense, soft, shiny and the most malleable and ductile pure metal known. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Gold is the most malleable and ductile of all metals; a single gram can be beaten into a sheet of 1 square meter, or an ounce into 300 square feet. Gold leaf can be beaten thin enough to become translucent. A total of 165,000 tonnes of gold have been mined in human history, as of 2009.


80 Mercury

Mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine.As compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity. With a freezing point of −38.83 °C and boiling point of 356.73°C, mercury has one of the broadest ranges of its liquid state of any metal.


81 Thallium

This soft gray poor metal resembles tin but discolors when exposed to air. Thallium is highly toxic and was used in rat poisons and insecticides. Thallium is extremely soft and malleable and can be cut with a knife at room temperature. It has a metallic luster, but when exposed to air, it quickly tarnishes with a bluish-gray tinge that resembles lead. It may be preserved by keeping it under oil. A heavy layer of oxide builds up on thallium if left in air.


82 Lead

Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed to air. Lead has a shiny chrome-silver luster when it is melted into a liquid.


83 Bismuth

Bismuth, a trivalent poor metal, resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead, and brittle, with a silvery white color, and often a pink tinge owing to the surface oxide. Bismuth is the most naturally diamagnetic of all metals, and only mercury has a lower thermal conductivity.


84 Polonium

A rare and highly radioactive metalloid, polonium is chemically similar to bismuth and tellurium, and it occurs in uranium ores. Polonium has been studied for possible use in heating spacecraft. It is unstable; all isotopes of polonium are radioactive.


85 Astatine

It is the heaviest known halogen. Astatine is produced by radioactive decay in nature, but due to its short half life it is found only in minute amounts. Astatine is currently the rarest naturally occurring element, with less than 30 grams estimated to be contained in the entire Earth's crust.


86 Radon

It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as the decay product of uranium. It is one of the densest substances that remains a gas under normal conditions and is considered to be a health hazard due to its radioactivity.


87 Francium

It has one of the lowest electronegativities of all known elements, and is the second rarest naturally occurring element (after astatine). Francium is a highly radioactive metal that decays into astatine, radium, and radon. As an alkali metal, it has one valence electron.


88 Radium

Its appearance is almost pure white, but it readily oxidizes on exposure to air, turning black. Radium is an alkaline earth metal that is found in trace amounts in uranium ores The heaviest of the alkaline earth metals, radium is intensely radioactive and resembles barium in its chemical behavior.


103 Lawrencium

Its most stable known isotope is 262Lr, with a half-life of approximately 3.6 hours. Little is known of the chemistry but there is strong evidence for the formation of a trivalent ion in aqueous solution, confirming lawrencium's place as the final member of the actinide elements.


104 Rutherfordium

Chemistry experiments have confirmed that rutherfordium behaves as the heavier homologue to hafnium in group 4. Rutherfordium is a radioactive synthetic element whose most stable known isotope is 267Rf with a half-life of approximately 1.3 hours.


105 Dubnium

This is a radioactive synthetic element whose most stable isotope is 268Db with a half life of 28 hours. This is the longest lived transactinide isotope and is a reflection of the stability of the Z = 108 and N = 162 closed shells and the effect of odd particles in nuclear decay.


106 Seaborgium

Seaborgium is a synthetic element whose most stable isotope 271Sg has a half-life of 1.9 minutes. Chemistry experiments with seaborgium have firmly placed it in group 6 as a heavier homologue to tungsten.


107 Bohrium

It is a synthetic element whose most stable known isotope, 270Bh, has a half-life of 61 seconds. Chemical experiments have confirmed bohrium's predicted position as a heavier homologue to rhenium with the formation of a stable +7 oxidation state.[


108 Hassium

Experiments have confirmed that hassium is a typical member of group 8 showing a stable +8 oxidation state, analogous to osmium. Several isotopes are known, with 269Hs being the longest-lived with a half-life of ~10 s. More than 100 atoms of hassium have been synthesized to date in various cold and hot fusion reactions, both as a parent nucleus and decay product.


109 Meitnerium

Sufficiently stable isotope is not known at this time which would allow chemical experiments to confirm its position, unlike its lighter neighbours. It was first synthesized in 1982 and several isotopes are currently known.


110 Darmstadtium

This synthetic element is one of the so-called super-heavy atoms and was first synthesized in 1994. The longest-lived and heaviest isotope known is 281aDs with a half-life of ~10 s although a possible nuclear isomer, 281bDs has an unconfirmed half-life of about 4 minutes.


111 Roentgenium

Stable isotope is not known at this time that would allow its position as a heavier homologue of gold to be confirmed. Roentgenium was first observed in 1994 and several isotopes have been synthesized since its first discovery.


112 Copernicium

Copernicium is currently the highest-numbered element to be officially recognized by the International Union of Pure and Applied Chemistry (IUPAC). The most stable isotope discovered to date is 285Cn with a half-life of ≈30 s, although evidence exists that 285Cn may have a nuclear isomer with a much longer half-life of 8.9 min. In total, about 75 atoms of copernicium have been detected using various nuclear reactions.[


57 Lanthanum

Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table and is the first element of the lanthanide series. It is found in some rare-earth minerals, usually in combination with cerium and other rare earth elements. Lanthanum is a malleable, ductile, and soft metal that oxidizes rapidly when exposed to air.


58 Cerium

It is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet Ceres. Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight. It is found in a number of minerals, the most important being monazite and bastnasite. Commercial applications of cerium are numerous.


59 Praseodymium

Praseodymium is a soft, silvery, malleable and ductile metal in the lanthanide group. It is somewhat more resistant to corrosion in air.


60 Neodymium

Neodymium, a rare earth metal, was present in classical mischmetal to the extent of about 18%. The metal has a bright, silvery metallic luster; however, as one of the more reactive rare earth (lanthanide) metals, it quickly oxidizes in air. The oxide layer then falls off, which exposes the metal to further oxidation.


61 Promethium

It is notable for being the only other exclusively radioactive element besides technetium which is followed by chemical elements that have stable isotopes. Not found naturally on Earth, has a half=life of only 18 years. Some scientists claim to have detected it in our own Sun, but it is not widely accepted.


62 Samarium

Samarium is a rare earth metal having the hardness and density similar to those of zinc. It is a moderately hard silvery metal which readily oxidizes in air. Samarium has no significant biological role and is only slightly toxic.


63 Europium

Europium is a ductile metal that is hard as lead. It crystallizes in a body-centered cubic habit. Europium is the most reactive of the rare earth elements. It rapidly oxidizes in air: bulk oxidation of a centimeter-sized sample occurs within several days.


64 Gadolinium

It is a silvery-white, malleable and ductile rare-earth metal. Gadolinium has exceptionally high absorption of neutrons and therefore is used for shielding in neutron radiography and in nuclear reactors. Because of its paramagnetic properties, solutions of organic gadolinium complexes and gadolinium compounds are the most popular intravenous MRI contrast agents in medical magnetic resonance imaging.


65 Terbium

It is a silvery-white rare earth metal that is malleable, ductile and soft enough to be cut with a knife. Terbium is never found in nature as a free element, but it is contained in many minerals, including cerite, gadolinite, monazite, xenotime and euxenite.


66 Dysprosium

It is a rare earth element with a metallic silver luster. Dysprosium is never found in nature as a free element, though it is found in various minerals, such as xenotime. Dysprosium is used for its high thermal neutron absorption cross-section in making control rods in nuclear reactors, for its high magnetic susceptibility to magnetization in data storage devices and as a component of Terfenol-D. Soluble dysprosium salts are mildly toxic, while the insoluble salts are considered non-toxic.


67 Holmium

Holmium is a relatively soft and malleable silvery-white metallic element, which is stable in dry air at room temperature. A rare earth metal, it is found in the minerals monazite and gadolinite. Holmium has the highest magnetic strength of any element and therefore is used for the polepieces of the strongest static magnets. Because holmium strongly absorbs nuclear fission-bred neutrons, it is also used in nuclear control rods.


68 Erbium

A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements on Earth. As such, it is a rare earth element which is associated with several other rare elements in the mineral gadolinite.


69 Thulium

It is an easily workable metal with a bright silvery-gray luster. Despite its high price and rarity, thulium is used as the radiation source in portable X-ray devices and in solid-state lasers.


70 Ytterbium

A soft silvery metallic element, ytterbium is a rare earth element of the lanthanide series and is found in the minerals gadolinite, monazite, and xenotime.Ytterbium is a soft, malleable and rather ductile element that exhibits a bright silvery luster. A rare earth element, it is easily attacked and dissolved by mineral acids, slowly reacts with water, and oxidizes in air.


89 Actinium

Actinium is a soft, silvery-white radioactive metal. It reacts rapidly with oxygen and moisture in air forming a white coating of actinium oxide that prevents further oxidation. 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.


90 Thorium

Thorium is a naturally occurring, slightly radioactive metal. Pure thorium is a silvery-white metal which is air-stable and retains its luster for several months. When contaminated with the oxide, thorium slowly tarnishes in air, becoming gray and finally black.


91 Protactinium

It is a dense, silvery-gray metal which readily reacts with oxygen, water vapor and inorganic acids. The average concentrations of protactinium in the Earth's crust is typically on the order of a few parts per trillion, but may reach up to a few parts per million in some uraninite ore deposits. Because of the scarcity, high radioactivity and high toxicity, there are currently no uses for protactinium outside of scientific research, and for this purpose, protactinium is mostly extracted from the spent nuclear fuel.


92 Uranium

Uranium has the second highest atomic weight of the naturally occurring elements, lighter only than plutonium-244. Its density is about 70% higher than that of lead, but not as dense as gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. In nature, uranium is found as uranium-238 (99.2742%), uranium-235 (0.7204%), and a very small amount of uranium-234 (0.0054%). Uranium decays slowly by emitting an alpha particle. The half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years, making them useful in dating the age of the Earth. Many contemporary uses of uranium exploit its unique nuclear properties.


93 Neptunium

A radioactive metallic element, neptunium is the first transuranic element and belongs to the actinide series. Its most stable isotope, 237Np, is a by-product of nuclear reactors and plutonium production and it can be used as a component in neutron detection equipment. Neptunium is also found in trace amounts in uranium ores due to transmutation reactions.


94 Plutonium

It is an actinide metal of silvery-white appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen and silicon. When exposed to moist air, it forms oxides and hydrides that expand the sample up to 70% in volume, which in turn flake off as a powder that can spontaneously ignite. It is also a radioactive poison that accumulates in bone marrow. These and other properties make the handling of plutonium dangerous. The most important isotope of plutonium is plutonium-239, with a half-life of 24,100 years. Plutonium-239 is the isotope most useful for nuclear weapons.


95 Americium

Americium is a relatively soft radioactive metal with silvery-white appearance. Most americium is produced by bombarding uranium or plutonium with alpha particles (helium ions) in nuclear reactors – one tonne of spent nuclear fuel contains about 100 grams of americium. It is widely used in commercial ionization chamber smoke detectors, as well as in neutron sources and industrial gauges. Several unusual applications, such as a nuclear battery or fuel for space ships with nuclear propulsion, have been proposed for the isotope 242mAm, but they are as yet hindered by the scarcity and high price of this nuclear isomer.


96 Curium

Most curium is produced by bombarding uranium or plutonium with alpha particles (helium ions) in nuclear reactors – one tonne of spent nuclear fuel contains about 20 grams of curium. It is a hard, dense silvery metal with relatively high for actinides melting and boiling points.


97 Berkelium

Berkelium is a soft, silvery-white, radioactive metal. Only 0.66 grams of berkelium were produced in the United States during the period from 1967 to 1983. There is no practical application of berkelium outside of scientific research.


98 Californium

Californium is one of the few transuranium elements that have practical applications. Most of these applications exploit the property of certain isotopes of californium to emit neutrons. For example, californium can be used to help start-up nuclear reactors, and is employed as a source of neutrons when studying materials with neutron diffraction and neutron spectroscopy.


99 Einsteinium

Einsteinium is a soft, silvery, paramagnetic metal. Because of the short half-life of all isotopes of einsteinium, all primordial einsteinium, that is einsteinium that could possibly be present on the Earth during its formation, should have decayed by now. Synthesis of einsteinium from naturally occurring actinides uranium and thorium in the Earth crust requires multiple neutron capture, which is an extremely unlikely event.


100 Fermium

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. It was discovered in the debris of the first hydrogen bomb explosion in 1952. Like all synthetic elements, isotopes of fermium are extremely radioactive and are considered highly toxic.


101 Mendelevium

A metallic radioactive transuranic element of the actinides, mendelevium is usually synthesized by bombarding einsteinium with alpha particles. There are no known uses of mendelevium and only trace amounts of the element have ever been produced.


102 Nobelium

Little is known about the element but limited chemical experiments have shown that it forms a stable divalent ion in solution as well as the predicted trivalent ion that is associated with its presence as one of the actinoids.