|
Group 11 Element
Group 11, by modern IUPAC numbering, is a group (periodic table), group of chemical elements in the periodic table, consisting of copper (Cu), silver (Ag), gold (Au), and roentgenium (Rg), although no chemical experiments have yet been carried out to confirm that roentgenium behaves like the heavier Homologous series, homologue to gold. Group 11, more specifically, the first three members are also known as the ''coinage metals'', due to their usage in minting coins—while the rise in metal prices mean that silver and gold are no longer used for circulating currency, remaining in use for bullion, copper remains a common metal in coins to date, either in the form of copper Cladding (metalworking), clad coinage or as part of the cupronickel alloy. They were most likely the first three elements discovered. Copper, silver, and gold all occur naturally in native element, elemental form. History All three stable elements of the group have been known since prehistoric times, as all of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Group 10 Element
Group 10, numbered by current IUPAC style, is the group of chemical elements in the periodic table that consists of nickel (Ni), palladium (Pd), platinum (Pt), and darmstadtium (Ds). All are d-block transition metals. All known isotopes of darmstadtium are radioactive with short half-lives, and are not known to occur in nature; only minute quantities have been synthesized in laboratories. Characteristics Chemical properties The ground state electronic configurations of palladium and platinum are exceptions to Madelung's rule. According to Madelung's rule, the electronic configuration of palladium and platinum are expected to be r5s2 4d8 and e4f14 5d8 6s2 respectively. However, the 5s orbital of palladium is empty, and the 6s orbital of platinum is only partially filled. The relativistic stabilization of the 7s orbital is the explanation to the predicted electron configuration of darmstadtium, which, unusually for this group, conforms to that predicted by the Aufbau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gold
Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal, a group 11 element, and one of the noble metals. It is one of the least reactivity (chemistry), reactive chemical elements, being the second-lowest in the reactivity series. It is solid under standard temperature and pressure, standard conditions. Gold often occurs in free elemental (native state (metallurgy), native state), as gold nugget, nuggets or grains, in rock (geology), rocks, vein (geology), veins, and alluvial deposits. It occurs in a solid solution series with the native element silver (as in electrum), naturally alloyed with other metals like copper and palladium, and mineral inclusions such as within pyrite. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides). Gold is resistant to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Configuration
In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. For example, the electron configuration of the neon atom is , meaning that the 1s, 2s, and 2p subshells are occupied by two, two, and six electrons, respectively. Electronic configurations describe each electron as moving independently in an orbital, in an average field created by the nuclei and all the other electrons. Mathematically, configurations are described by Slater determinants or configuration state functions. According to the laws of quantum mechanics, a level of energy is associated with each electron configuration. In certain conditions, electrons are able to move from one configuration to another by the emission or absorption of a quantum of energy, in the form of a photon. Knowledge of the electron configuration of different atoms is useful in understanding the structu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bismuth-209
Bismuth-209 (Bi) is an isotope of bismuth, with the longest known half-life of any radioisotope that undergoes α-decay (alpha decay). It has 83 protons and a magic number of 126 neutrons, and an atomic mass of 208.9803987 amu (atomic mass units). Primordial bismuth consists entirely of this isotope. Decay properties Bismuth-209 was long thought to have the heaviest stable nucleus of any element, but in 2003, a research team at the Institut d’Astrophysique Spatiale in Orsay, France, discovered that Bi undergoes alpha decay with a half-life of 20.1 exayears (2.01×10, or 20.1 quintillion years), over 10 times longer than the estimated age of the universe. The heaviest nucleus considered to be stable is now lead-208 and the heaviest stable monoisotopic element is gold ( gold-197). Theory had previously predicted a half-life of 4.6 years. It had been suspected to be radioactive for a long time. The decay produces a 3.14 MeV alpha particle plus thallium-205. Bismuth-209 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lower Mesopotamia
Lower Mesopotamia is a historical region of Mesopotamia. It is located in the alluvial plain of Iraq from the Hamrin Mountains to the Faw Peninsula near the Persian Gulf. In the Middle Ages it was also known as the '' Sawad'' and al-Jazira al-sflia ("Lower Jazira"), which strictly speaking designated only the southern alluvial plain, and Arab Iraq, as opposed to Persian Iraq, the Jibal. Lower Mesopotamia was home to Sumer and Babylonia. Delimitation The medieval Arab geographers placed the northern border between Iraq and Upper Mesopotamia (the ''Jazirah'') in a line running from Anbar on the Euphrates to Tikrit on the Tigris, although later it was shifted to a line running due west from Tikrit, thus including several towns on the Euphrates past Anbar into Iraq. Geography An alluvial plain begins north of Tikrit Near Hamrin Mountains and extends to the Persian Gulf. Here the Tigris and Euphrates lie above the level of the plain in many places, and the whole area is a rive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pre-dynastic Period In Egypt
Prehistoric Egypt and Predynastic Egypt was the period of time starting at the first human settlement and ending at the First Dynasty of Egypt around 3100 BC. At the end of prehistory, "Predynastic Egypt" is traditionally defined as the period from the final part of the Neolithic period beginning c. 6210 BC to the end of the Naqada III period c. 3000 BC. The dates of the Predynastic period were first defined before widespread archaeological excavation of Egypt took place, and recent finds indicating a very gradual Predynastic development have led to controversy over when exactly the Predynastic period ended. Thus, various terms such as " Protodynastic period", "Zero Dynasty" or "Dynasty 0" are used to name the part of the period which might be characterized as Predynastic by some and Early Dynastic by others. The Predynastic period is generally divided into cultural eras, each named after the place where a certain type of Egyptian settlement was first discovered. However, the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleolithic
The Paleolithic or Palaeolithic ( years ago) ( ), also called the Old Stone Age (), is a period in human prehistory that is distinguished by the original development of stone tools, and which represents almost the entire period of human prehistoric technology. It extends from the earliest known use of stone tools by Hominini, hominins, 3.3 million years ago, to the end of the Pleistocene, 11,650 Before Present#Radiocarbon calibration, cal Before Present, BP. The Paleolithic Age in Europe preceded the Mesolithic Age, although the date of the transition varies geographically by several thousand years. During the Paleolithic Age, hominins grouped together in small societies such as band society, bands and subsisted by gathering plants, fishing, and hunting or scavenging wild animals. The Paleolithic Age is characterized by the use of Knapping, knapped stone tools, although at the time humans also used wood and bone tools. Other organic commodities were adapted for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Native Metal
A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native element mineral, native deposits singly or in alloys include antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron, manganese, molybdenum, nickel, niobium, rhenium, tantalum, tellurium, tin, titanium, tungsten, vanadium, and zinc, as well as the gold group (gold, copper, lead, aluminium, mercury (element), mercury, silver) and the platinum group (platinum, iridium, osmium, palladium, rhodium, ruthenium). Among the alloys found in native state have been brass, bronze, pewter, German silver, osmiridium, electrum, white gold, silver-mercury amalgam (chemistry), amalgam, and gold-mercury amalgam. Only gold, silver, copper and the platinum group occur native in large amounts. Over geological time scales, very few metals can resist natural weathering processes like oxidation, so mainly the less reactive metals such as gold and platinum are found as native metal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extraction Metallurgy
Extractive metallurgy is a branch of metallurgical engineering wherein process and methods of extraction of metals from their natural mineral deposits are studied. The field is a materials science, covering all aspects of the types of ore, washing, concentration, separation, chemical processes and extraction of pure metal and their alloying to suit various applications, sometimes for direct use as a finished product, but more often in a form that requires further working to achieve the given properties to suit the applications. The field of ferrous and non-ferrous extractive metallurgy have specialties that are generically grouped into the categories of mineral processing, hydrometallurgy, pyrometallurgy, and electrometallurgy based on the process adopted to extract the metal. Several processes are used for extraction of the same metal depending on occurrence and chemical requirements. Mineral processing Mineral processing begins with beneficiation, consisting of initially b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Native Element
Native element minerals are those elements that occur in nature in uncombined form with a distinct mineral structure. The elemental class includes metals, intermetallic compounds, alloys, metalloids, and nonmetals. The Nickel–Strunz classification system also includes the naturally occurring phosphides, silicides, nitrides, carbides, and arsenides. Elements The following elements occur as native element minerals or alloys: Nickel–Strunz Classification -01- Native elements This list uses the Classification of Nickel–Strunz (mindat.org, 10 ed, pending publication). ;Abbreviations: * "*" – discredited (IMA/CNMNC status). * "?" – questionable/doubtful (IMA/CNMNC status). * "REE" – Rare-earth element (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) * "PGE" – Platinum-group element (Ru, Rh, Pd, Os, Ir, Pt) * 03.C Aluminofluorides, 06 Borates, 08 Vanadates (04.H V ,6/sup> Vanadates), 09 Silicates: ** Neso: insular (from Greek νησος n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cupronickel
Cupronickel or copper–nickel (CuNi) is an alloy of copper with nickel, usually along with small quantities of other metals added for strength, such as iron and manganese. The copper content typically varies from 60 to 90 percent. ( Monel is a nickel–copper alloy that contains a minimum of 52 percent nickel.) Despite its high copper content, cupronickel is silver in colour. Cupronickel is highly resistant to corrosion by salt water, and is therefore used for piping, heat exchangers and condensers in seawater systems, as well as for marine hardware. It is sometimes used for the propellers, propeller shafts, and hulls of high-quality boats. Other uses include military equipment and chemical industry, petrochemical industry, and electrical industries. In decorative use, a cupronickel alloy called nickel silver is common, although it contains additional zinc but no silver. Another common 20th-century use of cupronickel was silver-coloured coins. For this use, the typical alloy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladding (metalworking)
Cladding is the bonding together of dissimilar metals. It is different from fusion welding or adhesive, gluing as a method to fasten the metals together. Cladding is often achieved by extrude, extruding two metals through a die (manufacturing), die as well as machine press, pressing or cold rolling, rolling sheets together under high pressure. The United States Mint uses cladding to manufacture coins from different metals. This allows a cheaper metal to be used as a filler. For example, dimes and quarters struck since 1965 have cores made from pure copper, with a clad layer consisting of 75% copper and 25% nickel added during production. Half dollars struck from 1965 to 1969 for circulation and in 1970 for collectors also incorporated cladding, albeit in the case of those coins, the core was a mixture of 20.9% silver and 79.1% copper, and its clad layer was 80% silver and 20% copper. Half dollars struck since 1971 are produced identically to the dimes and quarters. Laser cladding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
