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History Of Chemistry
The history of chemistry represents a time span from ancient history to the present. By 1000 BC, civilizations used technologies that would eventually form the basis of the various branches of chemistry. Examples include the discovery of fire, extracting metals from ores, making pottery and glazes, fermenting beer and wine, extracting chemicals from plants for medicine and perfume, rendering fat into soap, making glass, and making alloys like bronze. The protoscience of chemistry, and alchemy, was unsuccessful in explaining the nature of matter and its transformations. However, by performing experiments and recording the results, alchemists set the stage for modern chemistry. The history of chemistry is intertwined with the history of thermodynamics, especially through the work of Willard Gibbs. Ancient history Early humans Fire Arguably the first chemical reaction used in a controlled manner was combustion, fire. However, for millennia fire was seen simply as a mystical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion does not always result in fire, because a flame is only visible when substances undergoing combustion vaporize, but when it does, a flame is a characteristic indicator of the reaction. While activation energy must be supplied to initiate combustion (e.g., using a lit match to light a fire), the heat from a flame may provide enough energy to make the reaction self-sustaining. The study of combustion is known as combustion science. Combustion is often a complicated sequence of elementary reaction, elementary Radical (chemistry), radical reactions. Solid fuels, such as wood and coal, first undergo endothermic pyrolysis to produce gaseous fuels whose combustion then supplies the heat required to produce more of them. Combustion is often hot e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Egypt
Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower Egypt were amalgamated by Menes, who is believed by the majority of List of Egyptologists, Egyptologists to have been the same person as Narmer. The history of ancient Egypt unfolded as a series of stable kingdoms interspersed by the "Periodization of ancient Egypt, Intermediate Periods" of relative instability. These stable kingdoms existed in one of three periods: the Old Kingdom of Egypt, Old Kingdom of the Early Bronze Age; the Middle Kingdom of Egypt, Middle Kingdom of the Middle Bronze Age; or the New Kingdom of Egypt, New Kingdom of the Late Bronze Age. The pinnacle of ancient Egyptian power was achieved during the New Kingdom, which extended its rule to much of Nubia and a considerable portion of the Levant. After this period, Egypt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metalworking
Metalworking is the process of shaping and reshaping metals in order to create useful objects, parts, assemblies, and large scale structures. As a term, it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale: from huge ships, buildings, and bridges, down to precise engine parts and delicate jewellery. The historical roots of metalworking predate recorded history; its use spans cultures, civilizations and millennia. It has evolved from shaping soft, native metals like gold with simple hand tools, through the smelting of ores and hot forging of harder metals like iron, up to and including highly technical modern processes such as machining and welding. It has been used as an industry, a driver of trade, individual hobbies, and in the creation of art; it can be regarded as both a science and a craft. Modern metalworking processes, though diverse and specialized, can be categorized into one of three broad areas known as forming, cutt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteoric Iron
Meteoric iron, sometimes meteoritic iron, is a native metal and early-universe protoplanetary-disk remnant found in meteorites and made from the elements iron and nickel, mainly in the form of the mineral phases kamacite and taenite. Meteoric iron makes up the bulk of iron meteorites but is also found in other meteorites. Apart from minor amounts of telluric iron, meteoric iron is the only naturally occurring native metal of the element iron (in metallic form rather than in an ore) on the Earth's surface. Mineralogy The bulk of meteoric iron consists of taenite and kamacite. Taenite is a face-centered cubic and kamacite a body-centered cubic iron-nickel alloy. Meteoric iron can be distinguished from telluric iron by its microstructure and perhaps by its chemical composition also, since meteoritic iron contains more nickel and less carbon. Trace amounts of gallium and germanium in meteoric iron can be used to distinguish different meteorite types. The meteoric iron in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper
Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable, unalloyed metallic form. This means that copper is a native metal. This led to very early human use in several regions, from . Thousands of years later, it was the first metal to be smelted from sulfide ores, ; the first metal to be cast into a shape in a mold, ; and the first metal to be purposely alloyed with another metal, tin, to create bronze, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver
Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. Silver is found in the Earth's crust in the pure, free elemental form ("native metal, native silver"), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc Refining (metallurgy), refining. Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes bimetallism, alongside gold: while it is more abundant than gold, it is much less abundant as a native metal. Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as "0.940 fine". As one of the seven metals of antiquity, silver has had an enduring role in most human cultures. Other than in currency and as an in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Varna Culture
The Varna culture was a Chalcolithic culture of northeastern Bulgaria, dated , contemporary and closely related with the Gumelnița culture. The oldest golden artifacts in the world (4600 BC - 4200 BC) were found in the Necropolis of Varna. These artefacts are on display in the Varna Archaeological Museum. The site was accidentally discovered in October 1972 by excavator operator Raycho Marinov. Research excavation was under the direction of Mihail Lazarov and Ivan Ivanov. About 30% of the estimated necropolis area is still not excavated. The Varna culture is characterized by polychrome pottery and rich cemeteries, the most famous of which are Varna Necropolis, the eponymous site, and the Durankulak lake complex, which comprises the largest prehistoric cemetery in southeastern Europe, with an adjoining coeval Neolithic settlement (published) and an unpublished and incompletely excavated Chalcolithic settlement. 294 graves have been found in the Varna necropolis, many contain ... [...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] |
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] |
South Africa
South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic Ocean, South Atlantic and Indian Ocean; to the north by the neighbouring countries of Namibia, Botswana, and Zimbabwe; to the east and northeast by Mozambique and Eswatini; and it encloses Lesotho. Covering an area of , the country has Demographics of South Africa, a population of over 64 million people. Pretoria is the administrative capital, while Cape Town, as the seat of Parliament of South Africa, Parliament, is the legislative capital, and Bloemfontein is regarded as the judicial capital. The largest, most populous city is Johannesburg, followed by Cape Town and Durban. Cradle of Humankind, Archaeological findings suggest that various hominid species existed in South Africa about 2.5 million years ago, and modern humans inhabited the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blombos Cave
Blombos Cave is an archaeological site located in Blombos Private Nature Reserve, about 300 km east of Cape Town on the Southern Cape coastline, South Africa. The cave contains Middle Stone Age (MSA) deposits currently dated at between c. 100,000 and 70,000 years Before Present (BP), and a Late Stone Age sequence dated at between 2000 and 300 years BP.Tribolo, C., et al. (2006) TL dating of burnt lithics from Blombos Cave (South Africa): further evidence for the antiquity of modern human behaviour. Archaeometry, 48, 341–357.Jacobs, Z., et al. (2006) Extending the chronology of deposits at Blombos Cave, South Africa, back to 140 ka using optical dating of single and multiple grains of quartz. Journal of Human Evolution, 51, 255–73.Henshilwood, Christopher S., et al. (2011) A 100,000-Year-Old Ochre-Processing Workshop at Blombos Cave, South Africa. Science, 334, 219–222, .Jacobs, Zenobia, et al. (2013) An improved OSL chronology for the Still Bay layers at Blombos Cave, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
