Group →	6
↓ Period
4 Period 4 element A period 4 element is one of the chemical elements in the fourth row of the periodic table of the elements. The periodic table is laid out in rows to illustrate recurring trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour...
5 Period 5 element A period 5 element is one of the chemical elements in the fifth row of the periodic table of the elements. The periodic table is laid out in rows to illustrate recurring trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour...
6 Period 6 element A period 6 element is one of the chemical elements in the sixth row of the periodic table of the elements, including the lanthanides...
7 Period 7 element A period 7 element is one of the chemical elements in the seventh row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical...
---- Legend Transition metal Primordial element Synthetic

A Group 6 element is one in the series of elements

Chemical element

A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...

 in group 6

Periodic table group

In chemistry, a group is a vertical column in the periodic table of the chemical elements. There are 18 groups in the standard periodic table, including the d-block elements, but excluding the f-block elements....

 (IUPAC style) in the periodic table

Periodic table

The periodic table of the chemical elements is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus...

, which consists of the transition metal

Transition metal

The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some...

s chromium

Chromium

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. 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...

  (Cr), molybdenum

Molybdenum

Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...

  (Mo), tungsten

Tungsten

Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...

  (W), and seaborgium

Seaborgium

Seaborgium is a synthetic chemical element with the symbol Sg and atomic number 106.Seaborgium is a synthetic element whose most stable isotope 271Sg has a half-life of 1.9 minutes. A new isotope 269Sg has a potentially slightly longer half-life based on the observation of a single decay...

  (Sg).

Like other groups, the members of this family show patterns in its electron configuration

Electron configuration

In atomic physics and quantum chemistry, electron configuration is the arrangement of electrons of an atom, a molecule, or other physical structure...

, especially the outermost shells resulting in trends in chemical behavior:

Z Atomic number In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...	Element Chemical element A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...	No. of electrons/shell Electron shell An electron shell may be thought of as an orbit followed by electrons around an atom's nucleus. The closest shell to the nucleus is called the "1 shell" , followed by the "2 shell" , then the "3 shell" , and so on further and further from the nucleus. The shell letters K,L,M,.....
24	chromium	2, 8, 13, 1
42	molybdenum	2, 8, 18, 13, 1
74	tungsten	2, 8, 18, 32, 12, 2
106	seaborgium	2, 8, 18, 32, 32, 12, 2

"Group 6" is the new IUPAC name for this group; the old style name was "group VIA" in the old European system or "group VIB" in the old US system. Group 6 must not be confused with the group with the old-style group names of either VIB (European system) or VIA (US system); that group is now called group 16.

History

Discoveries

The first reported use of chromium dates from the late 3rd century BC (by Qin Dynasty

Qin Dynasty

The Qin Dynasty was the first imperial dynasty of China, lasting from 221 to 207 BC. The Qin state derived its name from its heartland of Qin, in modern-day Shaanxi. The strength of the Qin state was greatly increased by the legalist reforms of Shang Yang in the 4th century BC, during the Warring...

) in China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

: weapons from the artea were analyzed and found out to be coated with chromium, which allowed to prevent their corrosion. Since then, chromium has not been reported up to July 26, 1761, when Johann Gottlob Lehmann found an orange-red mineral in the Beryozovskoye mines

Beryozovskoye deposit

Beryozovskoye deposit, Berezovskoe gold deposit, Berezovsky deposit, Berezovsk Mines, and some other names is the first known primary deposit of gold in Russia. It is located 13 km northwest of Yekaterinburg in the central Urals Federal District. It was discovered in 1745 by a raskolnik Yerofey...

 in the Ural Mountains

Ural Mountains

The Ural Mountains , or simply the Urals, are a mountain range that runs approximately from north to south through western Russia, from the coast of the Arctic Ocean to the Ural River and northwestern Kazakhstan. Their eastern side is usually considered the natural boundary between Europe and Asia...

 of Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, which he named "Siberian red lead," which was found out in less than 10 years to be a bright yellow

Yellow

Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, with no significant stimulation of the S cone cells. Light with a wavelength of 570–590 nm is yellow, as is light with a suitable mixture of red and green...

 pigment. Though misidentified as a lead

Lead

Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. 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...

 compound with selenium

Selenium

Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...

 and iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 components, the mineral was crocoite

Crocoite

Crocoite is a mineral consisting of lead chromate, PbCrO4, and crystallizing in the monoclinic crystal system. It is sometimes used as a paint, being identical in composition with the artificial product chrome yellow. It was discovered at Berezovsky deposit near Ekaterinburg in the Urals in 1766;...

 with a formula of PbCrO₄. Studying the mineral in 1797, Louis Nicolas Vauquelin

Louis Nicolas Vauquelin

Nicolas Louis Vauquelin , was a French pharmacist and chemist.-Early life:Vauquelin was born at Saint-André-d'Hébertot in Normandy, France. His first acquaintance with chemistry was gained as laboratory assistant to an apothecary in Rouen , and after various vicissitudes he obtained an introduction...

 produced chromium trioxide by mixing crocoite with hydrochloric acid

Hydrochloric acid

Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....

 metallic chromium by heating the oxide in a charcoal oven a year later. He was also able to detect traces of chromium in precious gemstone

Gemstone

A gemstone or gem is a piece of mineral, which, in cut and polished form, is used to make jewelry or other adornments...

s, such as ruby

Ruby

A ruby is a pink to blood-red colored gemstone, a variety of the mineral corundum . The red color is caused mainly by the presence of the element chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires...

 or emerald

Emerald

Emerald is a variety of the mineral beryl colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the 10 point Mohs scale of mineral hardness...

.

Molybdenite

Molybdenite

Molybdenite is a mineral of molybdenum disulfide, MoS2. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum atoms sandwiched between sheets of sulfur atoms...

—the principal ore from which molybdenum is now extracted—was previously known as molybdena, which was confused with and often implemented as though it were graphite

Graphite

The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...

. Like graphite, molybdenite can be used to blacken a surface or as a solid lubricant. Even when molybdena was distinguishable from graphite, it was still confused with a galena

Galena

Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...

 (a common lead ore), which took its name from Ancient Greek

Ancient Greek

Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

  , meaning lead. It was not until 1778 that Swedish

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 chemist Carl Wilhelm Scheele

Carl Wilhelm Scheele

Carl Wilhelm Scheele was a German-Swedish pharmaceutical chemist. Isaac Asimov called him "hard-luck Scheele" because he made a number of chemical discoveries before others who are generally given the credit...

 realized that molybdena was neither graphite nor lead. He and other chemists then correctly assumed that it was the ore of a distinct new element, named molybdenum for the mineral in which it was discovered. Peter Jacob Hjelm successfully isolated molybdenum by using carbon

Carbon

Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 and linseed oil

Linseed oil

Linseed oil, also known as flaxseed oil, is a clear to yellowish oil obtained from the dried ripe seeds of the flax plant . The oil is obtained by cold pressing, sometimes followed by solvent extraction...

 in 1781.

In 1781, Carl Wilhelm Scheele

Carl Wilhelm Scheele

Carl Wilhelm Scheele was a German-Swedish pharmaceutical chemist. Isaac Asimov called him "hard-luck Scheele" because he made a number of chemical discoveries before others who are generally given the credit...

 discovered that a new acid

Acid

An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

, tungstic acid

Tungstic acid

Tungstic acid refers to hydrated forms of tungsten trioxide, WO3.The simplest form, the monohydrate, is WO3.H2O, the dihydrate WO3.2H2O is also known. The solid state structure of WO3.H2O consists of layers of octahedrally coordinated WO5 units where 4 vertices are shared. the dihydrate has the...

, could be made from scheelite

Scheelite

Scheelite is a calcium tungstate mineral with the chemical formula CaWO4. It is an important ore of tungsten. Well-formed crystals are sought by collectors and are occasionally fashioned into gemstones when suitably free of flaws...

 (at the time named tungsten). Scheele and Torbern Bergman

Torbern Bergman

Torbern Olof Bergman was a Swedish chemist and mineralogist noted for his 1775 Dissertation on Elective Attractions, containing the largest chemical affinity tables ever published...

 suggested that it might be possible to obtain a new metal by reducing this acid. In 1783, José and Fausto Elhuyar

Fausto Elhuyar

Fausto de Elhuyar was a Spanish chemist, and the joint discoverer of tungsten with his brother Juan José Elhuyar in 1783. Fausto de Elhuyar was in charge, under a King of Spain commission, of organizing the School of Mines in México City and so was responsible of building an architectural jewel...

 found an acid made from wolframite that was identical to tungstic acid. Later that year, in Spain

Spain

Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

, the brothers succeeded in isolating tungsten by reduction of this acid with charcoal

Charcoal

Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...

, and they are credited with the discovery of the element.

Historical development and uses

During the 1800s, chromium was primarily used as a component of paints and in tanning

Tanning

Tanning is the making of leather from the skins of animals which does not easily decompose. Traditionally, tanning used tannin, an acidic chemical compound from which the tanning process draws its name . Coloring may occur during tanning...

 salts. At first, crocoite from Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

 was the main source, but in 1827, a larger chromite deposit was discovered near Baltimore

Baltimore

Baltimore is the largest independent city in the United States and the largest city and cultural center of the US state of Maryland. The city is located in central Maryland along the tidal portion of the Patapsco River, an arm of the Chesapeake Bay. Baltimore is sometimes referred to as Baltimore...

, United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. This made the United states the largest producer of chromium products until 1848 when large deposits of chromite where found near Bursa, Turkey

Turkey

Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

. Chromium was used for electroplating as early as 1848, but this use only became widespread with the development of an improved process in 1924.

For about a century after its isolation, molybdenum had no industrial use, owing to its relative scarcity, difficulty extracting the pure metal, and the immaturity of the metallurgical subfield. Early molybdenum steel alloys showed great promise in their increased hardness, but efforts were hampered by inconsistent results and a tendency toward brittleness and recrystallization. In 1906, William D. Coolidge filed a patent for rendering molybdenum ductile

Ductility

In materials science, ductility is a solid material's ability to deform under tensile stress; this is often characterized by the material's ability to be stretched into a wire. Malleability, a similar property, is a material's ability to deform under compressive stress; this is often characterized...

, leading to its use as a heating element for high-temperature furnaces and as a support for tungsten-filament light bulbs; oxide formation and degradation require that moly be physically sealed or held in an inert gas. In 1913, Frank E. Elmore developed a flotation process

Flotation process

Flotation process is a method of separation widely used in the wastewater treatment and mineral processing industries.Various flotation processes include the following:* Dissolved air flotation...

 to recover molybdenite

Molybdenite

Molybdenite is a mineral of molybdenum disulfide, MoS2. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum atoms sandwiched between sheets of sulfur atoms...

 from ores; flotation remains the primary isolation process. During the first World War

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, demand for molybdenum spiked; it was used both in armor plating and as a substitute for tungsten in high speed steel

High speed steel

High speed steelMost copyeditors today would tend to choose to style the unit adjective high-speed with a hyphen, rendering the full term as high-speed steel, and this styling is not uncommon . However, it is true that in the metalworking industries the styling high speed steel is long-established...

s. Some British tanks were protected by 75 mm (3 in) manganese steel

Mangalloy

Mangalloy, also called manganese steel or Hadfield steel, is a steel alloy containing an average of around 13% manganese. Mangalloy is known for its high impact strength and resistance to abrasion.-Material properties:...

 plating, but this proved to be ineffective. The manganese steel plates were replaced with 25 mm (1 in) molybdenum-steel plating allowing for higher speed, greater maneuverability, and better protection. After the war, demand plummeted until metallurgical advances allowed extensive development of peacetime applications. In World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, molybdenum again saw strategic importance as a substitute for tungsten in steel alloys.

In World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, tungsten played a significant role in background political dealings. Portugal

Portugal

Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

, as the main European source of the element, was put under pressure from both sides, because of its deposits of wolframite ore at Panasqueira

Panasqueira

Panasqueira is one of the largest tungsten mines in the world. It is located in Covilhã, Castelo Branco, Portugal.-Geology:The deposit is located in a region in which Precambrian shale, greywacke and sandstone units were intruded by the Panasquieira Granite. Contact metamorphism adjacent to the...

. Tungsten's resistance to high temperatures and its strengthening of alloys made it an important raw material for the arms industry.

Chemistry

Unlike other groups, the members of this family do not show patterns in its electron configuration

Electron configuration

In atomic physics and quantum chemistry, electron configuration is the arrangement of electrons of an atom, a molecule, or other physical structure...

, as two lighter members of the group are exceptions from the Aufbau principle

Aufbau principle

The Aufbau principle is used to determine the electron configuration of an atom, molecule or ion. The principle postulates a hypothetical process in which an atom is "built up" by progressively adding electrons...

:

Z Atomic number In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...	Element Chemical element A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...	Numerical Bohr model Electron shell An electron shell may be thought of as an orbit followed by electrons around an atom's nucleus. The closest shell to the nucleus is called the "1 shell" , followed by the "2 shell" , then the "3 shell" , and so on further and further from the nucleus. The shell letters K,L,M,.....
24	chromium	2, 8, 13, 1
42	molybdenum	2, 8, 18, 13, 1
74	tungsten	2, 8, 18, 32, 12, 2
106	seaborgium	2, 8, 18, 32, 32, 12, 2

Most of the chemistry has been observed only for the first three members of the group, the chemistry of seaborgium is not very established and therefore the rest of the section deals only with its upper neighbors in the periodic table

Periodic table

The periodic table of the chemical elements is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus...

. The elements in the group, like those of groups 7—11, have high melting points, and form volatile compounds in higher oxidation states. All the elements of the group are relatively nonreactive metals with a high melting points (1907 °C, 2477 °C, 3422 °C); that of tungsten is the highest of all metals. The metals form compounds in different oxidation states: chromium forms compounds in all states from -2 to +6: disodium pentacarbonylchromate, disodium decacarbonyldichromate, bis(benzene)chromium

Bis(benzene)chromium

Bischromium is the organometallic compound with the formula Cr2. It is sometimes called dibenzenechromium. The compound played an important role in the development of sandwich compounds in organometallic chemistry and is the prototypical complex containg two arene ligands.-Preparation:The...

, tripotassium pentanitrocyanochromate, chromium(II) chloride

Chromium(II) chloride

Chromium chloride is the chemical compound with the formula CrCl2. This white, crystalline solid is used for the synthesis of other chromium complexes. CrCl2 is hygroscopic. It dissolves in water to give bright blue solutions that are easily oxidized by air to give Cr-containing products...

, chromium(III) oxide

Chromium(III) oxide

Chromium oxide is the inorganic compound of the formula Cr2O3. It is one of principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite.-Structure and properties:...

, chromium(IV) chloride

Chromium(IV) chloride

Chromium chloride, CrCl4 is an unstable chromium compound prepared by combining chromium chloride and chlorine gas at elevated temperatures; it decomposes back to those substances at room temperature....

, potassium tetraperoxochromate(V)

Potassium tetraperoxochromate(V)

Potassium peroxochromate, or potassium tetraperoxochromate, is an inorganic chemical having the chemical formula K3[Cr4]. A crystalline ionic solid with a brown color, it is the potassium salt of tetraperoxochromate, one of the few examples of chromium in the +5 oxidation...

, and chromium(VI) dichloride dioxide

Chromyl chloride

Chromyl chloride is a chemical compound with the formula CrO2Cl2. This compound is an opaque dark blood-red liquid at room temperature and pressure. It is tetrahedral, somewhat like SO2Cl2. CrO2Cl2 is similar to the most commonly encountered chromium derivative chromate, [CrO4]2−; both are...

; the same is also true for molybdenum and tungsten, but the stability of the +6 state grows down the group. Depending on oxidation states, the compounds are basic, amphoteric, or acidic; the acidity grows with the oxidation state of the metal.

Applications

• Alloys
• Catalysts
• Metallurgy, sometimes used in jet engines and gas turbines.
• Dyes and pigments
• Tanning
• hard materials

Biological occurrences

Group 6 is notable in that it contains some of the only elements in periods 5 and 6 with a known role in the biological chemistry of living organisms: molybdenum is common in enzymes of many organisms, and tungsten

Tungsten

Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...

 has been identified in an analogous role in enzymes from some archaea

Archaea

The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...

, such as Pyrococcus furiosus

Pyrococcus furiosus

Pyrococcus furiosus is an extremophilic species of Archaea. It can be classified as a hyperthermophile because it thrives best under extremely high temperatures—higher than those preferred of a thermophile...

. In contrast, and unusually for a first-row d-block transition metal, chromium appears to have few biological roles, although it is thought to form part of the glucose

Glucose

Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

 metabolism enzyme in some mammals.

See also

>Explanation of right side periodic table slice:

Transition metal Transition metal The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some... s

atomic number in black are solids

solid borders are older than the Earth Earth Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...  (Primordial elements)

dotted borders are made artificially (Synthetic element Synthetic element In chemistry, a synthetic element is a chemical element that is too unstable to occur naturally on Earth, and therefore has to be created artificially. So far 30 synthetic elements have been discovered—that is, synthesized... s)