"known as isotopes, from the Greek """" (""same place""). In 1914, a year before he was killed in action at Gallipoli, the English physicist Henry Moseley found a relationship between the X-ray wavelength of an element and its atomic number. He was then able to re-sequence the periodic table by nuclear charge, rather than by atomic weight. Before this discovery, atomic numbers were sequential numbers based on an element's atomic weight. Moseley's discovery showed that atomic numbers were in fact based upon experimental measurements. Using information about their X-ray wavelengths, Moseley placed argon (with an atomic number Z=18) before potassium"
"toxic to humans in large quantities, and <nowiki>bromine</nowiki>, a very toxic liquid. Many elements are essential to humans' survival, such as calcium being what forms bones. (*) Exception to the Madelung rule Potassium (K) is an alkali metal, placed under sodium and over rubidium, and is the first element of period 4. It is one of the most reactive elements in the periodic table, therefore usually only found in compounds. It tends to oxidize in air very rapidly, thus accounting for its rapid reaction with oxygen when freshly exposed to air. When freshly exposed, it is rather silvery, but it"
"Potassium Potassium is a chemical element with symbol K (from Neo-Latin ""kalium"") and atomic number 19. It was first isolated from potash, the ashes of plants, from which its name derives. In the periodic table, potassium is one of the alkali metals. All of the alkali metals have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge – a cation, which combines with anions to form salts. Potassium in nature occurs only in ionic salts. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air"
"Carbon Carbon (from ""coal"") is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Three isotopes occur naturally, C and C being stable, while C is a radionuclide, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity. Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Carbon's abundance, its unique"
"Alum-(K) Alum-(K) is a hydrous potassium aluminium sulfate mineral with formula KAl(SO)·12(HO). It is the mineral form of potassium alum and is referred to as potassium alum in older sources. It is a member of the alum group. It occurs as colorless to white, soft isometric crystals and efflorescence coatings. Rare crystals are octahedral in form if occurring as precipitates from neutral water solution, but cubic in form if the solution is alkaline. It occurs as a precipitate around volcanic fumaroles and solfataras. It also occurs as an alteration in argillaceous sediments or coal beds which contain oxidizing sulfide minerals"
"Alkali metal The alkali metals are a group (column) in the periodic table consisting of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). This group lies in the s-block of the periodic table of elements as all alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties. Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour. The alkali metals are all shiny, soft, highly reactive metals at"
"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"
"Periodic table The periodic table, or periodic table of elements, is a tabular arrangement of the chemical elements, ordered by their atomic number, electron configuration, and recurring chemical properties, whose structure shows ""periodic trends"". Generally, within one row (period) the elements are metals to the left, and non-metals to the right, with the elements having similar chemical behaviours placed in the same column. Table rows are commonly called periods and columns are called groups. Six groups have accepted names as well as assigned numbers: for example, group 17 elements are the halogens; and group 18 are the noble gases. Also"
"Period 2 element A period 2 element is one of the chemical elements in the second 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 behavior of the elements as their atomic number increases; a new row is started when chemical behavior begins to repeat, creating columns of elements with similar properties. The second period contains the elements lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, and neon. This situation can be explained by modern theories of atomic structure. In a quantum mechanical"
"inert. It is one of the so-called ""noble gases"". Neon is a trace component of the atmosphere without any biological role. Period 2 element A period 2 element is one of the chemical elements in the second 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 behavior of the elements as their atomic number increases; a new row is started when chemical behavior begins to repeat, creating columns of elements with similar properties. The second period contains the elements lithium, beryllium, boron,"
"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"
"Period 1 element A period 1 element is one of the chemical elements in the first row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate periodic (recurring) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The first period contains fewer elements than any other row in the table, with only two: hydrogen and helium. This situation can be explained by"
"KREEP KREEP, an acronym built from the letters K (the atomic symbol for potassium), REE (rare-earth elements) and P (for phosphorus), is a geochemical component of some lunar impact breccia and basaltic rocks. Its most significant feature is somewhat enhanced concentration of a majority of so-called ""incompatible"" elements (those that are concentrated in the liquid phase during magma crystallization) and the heat-producing elements, namely radioactive uranium, thorium, and potassium (due to presence of the radioactive K). The typical composition of KREEP includes about one percent, by mass, of potassium and phosphorus oxides, 20 to 25 parts per million of rubidium,"
"Copernicium Copernicium is a synthetic chemical element with symbol Cn and atomic number 112. It is an extremely radioactive element, and can only be created in a laboratory. The most stable known isotope, copernicium-285, has a half-life of approximately 29 seconds. Copernicium was first created in 1996 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany. It is named after the astronomer Nicolaus Copernicus. In the periodic table of the elements, copernicium is a d-block transactinide element and a group 12 element. During reactions with gold, it has been shown to be an extremely volatile metal, so"
"for nutrient cycling studies because potassium is a macronutrient required for life. Isotopes of potassium Potassium (K) has 25 known isotopes from K to K, with unconfirmed detection of K. Three isotopes occur naturally: stable K (93.3%) and K (6.7%), and the long-lived radioisotope K (0.012%). Naturally occurring radioactive K decays to stable Ar (10.72% of decays) by electron capture or positron emission (giving it the longest known positron-emitter nuclide half-life). Alternately, and most of the time (89.28%), it decays to stable Ca by beta decay. K has a half-life of 1.248×10 years. The long half life of this primordial"
"Group 9 element Group 9, numbered by IUPAC nomenclature, is a group of chemical element in the periodic table. Members are cobalt (Co), rhodium (Rh), iridium (Ir) and perhaps also the chemically uncharacterized meitnerium (Mt). These are all transition metals in the d-block. All known isotopes of meitnerium are radioactive with short half-lives, and it is not known to occur in nature; only minute quantities have been synthesized in laboratories. Like other groups, the members of this family show patterns in electron configuration, especially in the outermost shells, resulting in trends in chemical behavior; however, rhodium deviates from the pattern."
"lithium and fluorine (appearing twice), or left floating above the other elements and not assigned to any group in the periodic table. Helium is almost always placed above neon (which is in the p-block) in the periodic table as a noble gas, although it is occasionally placed above beryllium due to their similar electron configuration. Hydrogen (H) is the chemical element with atomic number 1. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H. With an atomic mass of 1.00794 amu, hydrogen is the lightest element. Hydrogen is"
"Hydrogen Hydrogen is a chemical element with symbol H and atomic number 1. With a standard atomic weight of , hydrogen is the lightest element on the periodic table. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass. Non-remnant stars are mainly composed of hydrogen in the plasma state. The most common isotope of hydrogen, termed ""protium"" (name rarely used, symbol H), has one proton and no neutrons. The universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless,"
"radioactive, and therefore present radioactive hazards. Period 6 element A period 6 element is one of the chemical elements in the sixth row (or ""period"") of the periodic table of the elements, including the lanthanides. 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 chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The sixth period contains 32 elements, tied for the most with period 7, beginning with caesium and"
"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"
"Rhodium, iridium, and meitnerium have no known biological roles. Group 9 element Group 9, numbered by IUPAC nomenclature, is a group of chemical element in the periodic table. Members are cobalt (Co), rhodium (Rh), iridium (Ir) and perhaps also the chemically uncharacterized meitnerium (Mt). These are all transition metals in the d-block. All known isotopes of meitnerium are radioactive with short half-lives, and it is not known to occur in nature; only minute quantities have been synthesized in laboratories. Like other groups, the members of this family show patterns in electron configuration, especially in the outermost shells, resulting in trends"
"Period 7 element A period 7 element is one of the chemical elements in the seventh 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 chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The seventh period contains 32 elements, tied for the most with period 6, beginning with francium and ending with oganesson, the heaviest element currently discovered."
"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"
"noble metals. The Δ""H"" and −Δ""H"" values are correlated for the alkaline earth metals. Unbinilium Unbinilium, also known as eka-radium or simply element 120, is the hypothetical chemical element in the periodic table with symbol Ubn and atomic number 120. ""Unbinilium"" and ""Ubn"" are the temporary systematic IUPAC name and symbol, until a permanent name is decided upon. In the periodic table of the elements, it is expected to be an s-block element, an alkaline earth metal, and the second element in the eighth period. It has attracted attention because of some predictions that it may be in the island"
"Period 6 element A period 6 element is one of the chemical elements in the sixth row (or ""period"") of the periodic table of the elements, including the lanthanides. 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 chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The sixth period contains 32 elements, tied for the most with period 7, beginning with caesium and ending with radon. Lead is currently"
"Period (periodic table) A period in the periodic table is a horizontal row. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, groups of elements in the same column have similar chemical and physical properties, reflecting the periodic law. For example, the alkali metals lie in the first column (group 1) and share similar properties, such as high reactivity and the tendency to lose one electron to arrive at a noble-gas electronic configuration. As of 2016, a"
"the Moon. KREEP KREEP, an acronym built from the letters K (the atomic symbol for potassium), REE (rare-earth elements) and P (for phosphorus), is a geochemical component of some lunar impact breccia and basaltic rocks. Its most significant feature is somewhat enhanced concentration of a majority of so-called ""incompatible"" elements (those that are concentrated in the liquid phase during magma crystallization) and the heat-producing elements, namely radioactive uranium, thorium, and potassium (due to presence of the radioactive K). The typical composition of KREEP includes about one percent, by mass, of potassium and phosphorus oxides, 20 to 25 parts per million"
"12 element in the periodic table, below zinc, cadmium and mercury. It is predicted to differ significantly from the lighter group 12 elements. The valence s-subshells of the group 12 elements and period 7 elements are expected to be relativistically contracted most strongly at copernicium. This and the closed-shell configuration of copernicium result in it probably being a very noble metal. Its metallic bonds should also be very weak, possibly making it extremely volatile, like the noble gases, and potentially making it gaseous at room temperature. However, it should be able to form metal–metal bonds with copper, palladium, platinum, silver,"
"Chalcogen The chalcogens () are the chemical elements in group 16 of the periodic table. This group is also known as the oxygen family. It consists of the elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and the radioactive element polonium (Po). The chemically uncharacterized synthetic element livermorium (Lv) is predicted to be a chalcogen as well. Often, oxygen is treated separately from the other chalcogens, sometimes even excluded from the scope of the term ""chalcogen"" altogether, due to its very different chemical behavior from sulfur, selenium, tellurium, and polonium. The word ""chalcogen"" is derived from a combination of"
"the seventh period, as they are calculated to have an additional so-called g-block, containing 18 elements with partially filled ""g-orbitals"" in each period. An eight-period table containing this block was suggested by Glenn T. Seaborg in 1969. It is not known how many elements are physically possible, if period 8 is complete, or if there is a period 9. Chemical series information for elements past hassium (except copernicium), is hypothetical and based on periodic trends. Superheavy elements may not exist, and may not follow the order of this table even if they do. Extended periodic table (detailed cells) This is"
"Group 12 element Group 12, by modern IUPAC numbering, is a group of chemical elements in the periodic table. It includes zinc (Zn), cadmium (Cd) and mercury (Hg). The further inclusion of copernicium (Cn) in group 12 is supported by recent experiments on individual copernicium atoms. Formerly this group was named ""IIB"" (pronounced as ""group two B"", as the ""II"" is a Roman numeral) by CAS and old IUPAC system. The three group 12 elements that occur naturally are zinc, cadmium and mercury. They are all widely used in electric and electronic applications, as well as in various alloys. The"
"Unbinilium Unbinilium, also known as eka-radium or simply element 120, is the hypothetical chemical element in the periodic table with symbol Ubn and atomic number 120. ""Unbinilium"" and ""Ubn"" are the temporary systematic IUPAC name and symbol, until a permanent name is decided upon. In the periodic table of the elements, it is expected to be an s-block element, an alkaline earth metal, and the second element in the eighth period. It has attracted attention because of some predictions that it may be in the island of stability, although newer calculations expect the island to actually occur at a slightly"
"spin of 4, while both of its decay daughters are even-even isotopes with spins of 0. K occurs in natural potassium (and thus in some commercial salt substitutes) in sufficient quantity that large bags of those substitutes can be used as a radioactive source for classroom demonstrations. In healthy animals and people, K represents the largest source of radioactivity, greater even than C. In a human body of 70 kg mass, about 4,400 nuclei of K decay per second. The decay of K to Ar enables a commonly used method for dating rocks. The conventional K-Ar dating method depends on"