"stars. Lithium, beryllium and boron are rare because although they are produced by nuclear fusion, they are then destroyed by other reactions in the stars. The elements from carbon to iron are relatively more common in the universe because of the ease of making them in supernova nucleosynthesis. Elements of higher atomic number than iron (element 26) become progressively more rare in the universe, because they increasingly absorb stellar energy in being produced. Elements with even atomic numbers are generally more common than their neighbors in the periodic table, also due to favorable energetics of formation. The abundance of elements"
"Period 3 element A period 3 element is one of the chemical elements in the third row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when the periodic table skips a row and a chemical behaviour begins to repeat, meaning that elements with similar behavior fall into the same vertical columns. The third period contains eight elements: sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine, and argon. The first"
"Group 11 element Group 11, by modern IUPAC numbering, is a group of chemical elements in the periodic table, consisting of copper (Cu), silver (Ag), and gold (Au). Roentgenium (Rg) is also placed in this group in the periodic table, although no chemical experiments have yet been carried out to confirm that it behaves like the heavier homologue to gold. Group 11 is also known as the ""coinage metals"", due to their former usage. They were most likely the first three elements discovered. Copper, silver, and gold all occur naturally in elemental form. All the elements of the group except"
"History of aluminium Aluminium or aluminum is a chemical element with symbol Al and atomic number 13. At standard conditions, aluminium forms a bright silvery metal; this metal is unusually light and resistant against corrosion. Chemically, aluminium is a main-group element that normally assumes the +3 oxidation state. Aluminium is the third most abundant element in the Earth's crust; as such, it is widespread in human-related activities. Aluminium is produced in tens of millions of metric tons; the metal is commonly alloyed to improve some characteristics, such as hardness. Aluminium has no biological role but is not particularly toxic. The"
"Neptunium Neptunium is a chemical element with symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. Its position in the periodic table just after uranium, named after the planet Uranus, led to it being named after Neptune, the next planet beyond Uranus. A neptunium atom has 93 protons and 93 electrons, of which seven are valence electrons. Neptunium metal is silvery and tarnishes when exposed to air. The element occurs in three allotropic forms and it normally exhibits five oxidation states, ranging from +3 to +7. It is radioactive, poisonous, pyrophoric, and can"
"6th period and in the 3rd group. Lanthanum is the first element and prototype of the lanthanide series. In the periodic table, it appears to the right of the alkaline earth metal barium and to the left of the lanthanide cerium. Lanthanum is often considered to be a group 3 element, along with its lighter congeners scandium and yttrium and its heavier congener, the radioactive actinium, although this classification is sometimes disputed. Similarly to scandium, yttrium, and actinium, the 57 electrons of a lanthanum atom are arranged in the configuration [Xe]5d6s, with three valence electrons outside the noble gas core."
"Aluminium Aluminium or aluminum is a chemical element with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic and 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. The chief ore of aluminium is bauxite. Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different"
"roles in all animals and some plants, making up bones and teeth, and used in some applications in cells, such as signals for cellular processeses. It is regarded as the most abundant mineral in the body's mass. Scandium (Sc) is the third element in period 4, between calcium and titanium, and is the first transition metal in the periodic table. Scandium is quite common in nature, but difficult to find because it is most prevalent in rare earth compounds, which are difficult to isolate elements from. Scandium has very few commercial applications because of the aforementioned facts, and currently its"
"(not avgas), and laboratory cultures can degrade aluminium. However, these life forms do not directly attack or consume the aluminium; rather, the metal is corroded by microbe waste products. Aluminium Aluminium or aluminum is a chemical element with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic and 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. The chief ore of"
"two make up all natural occurrence of lithium on Earth, although further isotopes have been synthesized. In ionic compounds, lithium loses an electron to become positively charged, forming the cation Li. Lithium is the first alkali metal in the periodic table, and the first metal of any kind in the periodic table. At standard temperature and pressure, lithium is a soft, silver-white, highly reactive metal. With a density of 0.564 g·cm, lithium is the lightest metal and the least dense solid element. Lithium is one of the few elements synthesized in the Big Bang, making it a primordial element. Lithium"
"50,000,000 metric tons. In 2015, it was a record 57,500,000 tons. Its real price (in 1998 United States dollars) in 2015 was $1,340 per metric ton ($1,940 per ton in contemporary dollars). History of aluminium Aluminium or aluminum is a chemical element with symbol Al and atomic number 13. At standard conditions, aluminium forms a bright silvery metal; this metal is unusually light and resistant against corrosion. Chemically, aluminium is a main-group element that normally assumes the +3 oxidation state. Aluminium is the third most abundant element in the Earth's crust; as such, it is widespread in human-related activities. Aluminium"
"named mendelevium in honor of D.I. Mendeleev, the first to arrange the elements in a periodic manner. Most recently, the synthesis of element 118 (since named oganesson) was reported in October 2006, and the synthesis of element 117 (tennessine) was reported in April 2010. Ten materials familiar to various prehistoric cultures are now known to be chemical elements: Carbon, copper, gold, iron, lead, mercury, silver, sulfur, tin, and zinc. Three additional materials now accepted as elements, arsenic, antimony, and bismuth, were recognized as distinct substances prior to 1500 AD. Phosphorus, cobalt, and platinum were isolated before 1750. Most of the"
"Actinide The actinide or actinoid (IUPAC nomenclature) series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium. Strictly speaking, both actinium and lawrencium have been labeled as group 3 elements, but both elements are often included in any general discussion of the chemistry of the actinide elements. Actinium is the more often omitted of the two, because its placement as a group 3 element is somewhat more common in texts and for semantic reasons: since ""actinide"" means ""like actinium"", it has been argued that actinium cannot logically be an actinide, even though IUPAC"
"below, while the f-block only has 14 columns. One lanthanide and actinide each are d-block elements, belonging to group 3 with scandium and yttrium, though whether these are the first of each series (lanthanum and actinium) or the last (lutetium and lawrencium) has been disputed. The tables below show lanthanum and actinium as group 3 elements, as this is the more common form in the literature. Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869. Mendeleev invented the table to illustrate recurring (""periodic"") trends in the properties of the elements. The"
"are incredibly shiny. This period is known to have a large number of exceptions to the Madelung rule. (*) Exception to the Madelung rule Rubidium is the first element placed in period 5. It is an alkali metal, the most reactive group in the periodic table, having properties and similarities with both other alkali metals and other period 5 elements. For example, rubidium has 5 electron shells, a property found in all other period 5 elements, whereas its electron configuration's ending is similar to all other alkali metals: s. Rubidium also follows the trend of increasing reactivity as the atomic"
"were ""earth"", ""water"", ""air"" and ""fire"". Similar ideas about these four elements also existed in other ancient traditions, such as Indian philosophy. The history of the periodic table is also a history of the discovery of the chemical elements. The first person in history to discover a new element was Hennig Brand, a bankrupt German merchant. Brand tried to discover the Philosopher's Stone — a mythical object that was supposed to turn inexpensive base metals into gold. In 1669 (or later), his experiments with distilled human urine resulted in the production of a glowing white substance, which he called ""cold"
"fresh mineral waters. ""Aluminium"" (symbol Al) or ""aluminum"" (American English) is a silvery white member of the boron group of chemical elements and a post-transition metal. It is not soluble in water under normal circumstances. Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth's crust. It makes up about 8% by weight of the Earth's solid surface. Aluminium metal is too reactive chemically to occur natively. Instead, it is found combined in over 270 different minerals. The chief ore of aluminium is bauxite. Aluminium is remarkable for the metal's low"
"two new elements, cesium and rubidium. In 1875, the Parisian chemist Paul Emile Lecoq de Boisbaudran used a spectroscope to discover a new metallic element. It was a silvery-white, soft metal with an atomic weight of 68, which he named gallium, after his native France. It also turned out to have a very low melting point, thus matching all the expected properties of the element Mendeleev expected to fill the gap he had left after zinc; indeed, this is exactly where the element was placed in the periodic table. Even though Mendeleev had left the necessary gap for gallium as"
"of three elements the existence of which was predicted in 1869 by the Russian chemist Dmitri Mendeleev when he first devised his periodic table. However, the element was not actually discovered for some time. In September 1885, a miner discovered a mineral sample in a silver mine and gave it to the mine manager, who determined that it was a new mineral and sent the mineral to Clemens A. Winkler. Winkler realized that the sample was 75% silver, 18% sulfur, and 7% of an undiscovered element. After several months, Winkler isolated the element and determined that it was element 32."
"Palladium Palladium is a chemical element with symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. 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. More than half the supply of palladium"
"chromium (Cr(III)) ion is considered an essential nutrient in humans for insulin, sugar and lipid metabolism. However, in 2014, the European Food Safety Authority, acting for the European Union, concluded that there was not sufficient evidence for chromium to be recognized as essential. While chromium metal and Cr(III) ions are not considered toxic, hexavalent chromium (Cr(VI)) is both toxic and carcinogenic. Abandoned chromium production sites often require environmental cleanup. Chromium is the fourth transition metal found on the periodic table, and has an electron configuration of [Ar] 3d 4s. It is also the first element in the periodic table whose"
"potassium and calcium, and is the first period in the d-block with the lighter transition metals. These include iron, the heaviest element forged in main-sequence stars and a principal component of the Earth, as well as other important metals such as cobalt, nickel, and copper. Almost all have biological roles. Completing the fourth period are the post-transition metals zinc and gallium, the metalloids germanium and arsenic, and the nonmetals selenium, bromine, and krypton. Period 5 has the same number of elements as period 4 and follows the same general structure but with one more post transition metal and one fewer"
"two, sodium and magnesium, are members of the s-block of the periodic table, while the others are members of the p-block. Note that there is a 3d subshell, but it is not filled until period 4, such giving the period table its characteristic shape of ""two rows at a time"". All of the period 3 elements occur in nature and have at least one stable isotope. As the atomic number of elements in Period 3 increases, the atomic radius decreases. As the atomic mass of elements in Period 3 increases, the electronegativity increases. As the atomic number of elements in"
"pulmonary agent in chemical warfare; however, chlorine is necessary to most forms of life, including humans, in form of chloride ions. Argon has no biological role. Like any gas besides oxygen, argon is an asphyxiant. Period 3 element A period 3 element is one of the chemical elements in the third row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when the periodic table skips a row and"
"Iron Iron is a chemical element with symbol Fe (from ) and atomic number 26. It 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, where it is the last element to be produced with release of energy before the violent collapse of a supernova, which scatters the iron into space. Like the other"
"Lanthanum Lanthanum is a chemical element with symbol La and atomic number 57. It 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, which would put it in group 3, although lutetium is sometimes placed in this position instead. Lanthanum is traditionally"
"13. The relatively inert noble gases, in group 18, bridge the most reactive groups of elements in the periodic table—the halogens in group 17 and the alkali metals in group 1. In 1789, Antoine Lavoisier published a list of 33 chemical elements, grouping them into gases, metals, nonmetals, and earths. Chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads based on their chemical properties. Lithium, sodium, and potassium, for example, were grouped together in a triad as soft, reactive metals. Döbereiner"
"atomic number gives a definitive, integer-based sequence for the elements. Moseley predicted, in 1913, that the only elements still missing between aluminium (Z=13) and gold (Z=79) were Z = 43, 61, 72, and 75, all of which were later discovered. The atomic number is the absolute definition of an element, and gives a factual basis for the ordering of the periodic table. The periodic table is used to predict the properties of new synthetic elements before they are produced and studied. In 1871, Mendeleev published his periodic table in a new form, with groups of similar elements arranged in columns"
"palladium-group platinum-group elements (PPGEs: Rh, Pt, Pd) based on their behaviour in geological systems. The three elements above the platinum group in the periodic table (iron, nickel and cobalt) are all ferromagnetic, these being the only known transition metals with this property. Naturally occurring platinum and platinum-rich alloys were known by pre-Columbian Americans for many years. Though the metal was used by pre-Columbian peoples, the first European reference to platinum appears in 1557 in the writings of the Italian humanist Julius Caesar Scaliger (1484–1558) as a description of a mysterious metal found in Central American mines between Darién (Panama) and"
"sequential number, based on the sequence of atomic masses, but modified somewhat where chemists found this modification to be desirable, such as by the Russian chemist, Dmitri Ivanovich Mendeleev. In his invention of the Periodic Table of the Elements, Mendeleev had interchanged the orders of a few pairs of elements in order to put them in more appropriate places in this table of the elements. For example, the metals cobalt and nickel had been assigned the atomic numbers 27 and 28, respectively, based on their known chemical and physical properties, even though they have nearly the same atomic masses. In"
"in his Periodic Table of the Elements, located between silicon and tin. Because of its position in his Periodic Table, Mendeleev called it ""ekasilicon (Es)"", and he estimated its atomic weight to be about 72.0. In mid-1885, at a mine near Freiberg, Saxony, a new mineral was discovered and named ""argyrodite"" because of the high silver content. The chemist Clemens Winkler analyzed this new mineral, which proved to be a combination of silver, sulfur, and a new element. Winkler was able to isolate the new element in 1886 and found it similar to antimony. He initially considered the new element"
"3d and 4p shells, in that order; however, there are exceptions, such as chromium. Every single one of these elements is stable, and many are extremely common in the Earth's crust and/or core; it is the last period with no unstable elements at all. Many of the transition metals in period 4 are incredibly strong, and therefore commonly used in industry, especially iron. Copper is one of three metals that are not silver or gray in color, along with caesium and gold. Three adjacent elements are known to be toxic, with arsenic one of the most well-known poisons, selenium being"
"state characteristic of the alkali metals), together into a group. His table placed hydrogen with the halogens. After 1869, Dmitri Mendeleev proposed his periodic table placing lithium at the top of a group with sodium, potassium, rubidium, caesium, and thallium. Two years later, Mendeleev revised his table, placing hydrogen in group 1 above lithium, and also moving thallium to the boron group. In this 1871 version, copper, silver, and gold were placed twice, once as part of group IB, and once as part of a ""group VIII"" encompassing today's groups 8 to 11. After the introduction of the 18-column table,"