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: the map shows the difference between the amount of sunlight Greenland reflected in the summer of 2011 versus the average percent it reflected between 2000 and 2006. Some areas reflect close to 20 percent less light than a decade ago. Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection While directiona... | Wikipedia:Albedo |
of the highest albedos among landforms. Most land areas are in an albedo range of 0.1 to 0.4. The average albedo of Earth is about 0.3. White-sky, black-sky, and blue-sky albedo For land surfaces, it has been shown that the albedo at a particular solar zenith angle θi can be approximated by the proportionate sum of two... | Wikipedia:Albedo |
Illumination Albedo is not directly dependent on the illumination because changing the amount of incoming light proportionally changes the amount of reflected light, except in circumstances where a change in illumination induces a change in the Earth'ssurface at that location (e.g. through melting of reflective ice). H... | Wikipedia:Albedo |
albedo variations between land, ice, or ocean surfaces can drive weather. The response of the climate system to an initial forcing is modified by feedbacks: increased by Positive feedback Albedo–temperature feedback When an area'salbedo changes due to snowfall, a snow–temperature feedback results. A layer of snowfall i... | Wikipedia:Albedo |
snow and ice melt by 60%. Just as fresh snow has a higher albedo than does dirty snow, the albedo of snow-covered sea ice is far higher than that of sea water. Sea water absorbs more solar radiation than would the same surface covered with reflective snow. When sea ice melts, either due to a rise in sea temperature or ... | Wikipedia:Albedo |
have a low albedo because the majority of the ultraviolet and visible spectrum is absorbed through photosynthesis. For this reason, the greater heat absorption by trees could offset some of the carbon benefits of afforestation (or offset the negative climate impacts of deforestation). In other words: The climate change... | Wikipedia:Albedo |
new forests in high latitudes (e.g., Siberia) were neutral or perhaps warming. Water Water reflects light very differently from typical terrestrial materials. The reflectivity of a water surface is calculated using the Fresnel equations. At the scale of the wavelength of light even wavy water is always smooth so the li... | Wikipedia:Albedo |
m−2. Black carbon is a bigger cause of the melting of the polar ice cap in the Arctic than carbon dioxide due to its effect on the albedo. Astronomical albedo is darker than Saturn even though they receive the same amount of sunlight. This is due to a difference in albedo (0.22 versus 0.499 in geometric albedo).In astr... | Wikipedia:Albedo |
& for _OC 0.07 \\ (6.944 _OC + 1.083) g cm^-3 & for _OC > 0.07 cases. History The term albedo was introduced into optics by Johann Heinrich Lambert in his 1760 work Photometria. See also * Bio-geoengineering * Cool roof * Daisyworld * Emissivity * Exitance * Global dimming * Ice–albedo feedback * Irradiance * Kirchhoff... | Wikipedia:Albedo |
International Atomic Time (abbreviated TAI, from its French name '''') is a high-precision Atomic clock TAI may be reported using traditional means of specifying days, carried over from non-uniform time standards based on the rotation of the Earth. Specifically, both Julian days and the Gregorian calendar are used. TAI... | Wikipedia:International Atomic Time |
instead considered to be creating a better realisation of Terrestrial Time (TT). History Early atomic time scales consisted of quartz clocks with frequencies calibrated by a single atomic clock; the atomic clocks were not operated continuously. Atomic timekeeping services started experimentally in 1955, using the first... | Wikipedia:International Atomic Time |
name EAL (Échelle Atomique Libre, meaning Free Atomic Scale''). The instant that the gravitational correction started to be applied serves as the epoch for Barycentric Coordinate Time (TCB), Geocentric Coordinate Time (TCG), and Terrestrial Time (TT), which represent three fundamental time scales in the Solar System. A... | Wikipedia:International Atomic Time |
References * * Footnotes Bibliography * * External links * BIPM technical services: Time Metrology * Time and Frequency Section - National Physical Laboratory, UK * IERS website * NIST Web Clock FAQs * History of time scales * NIST-F1 Cesium Fountain Atomic Clock * * Japan Standard Time Project, NICT, Japan * * Standar... | Wikipedia:International Atomic Time |
Alain Connes (; born 1 April 1947) is a French mathematician, known for his contributions to the study of operator algebras and noncommutative geometry. He was a professor at the , , Ohio State University and Vanderbilt University. He was awarded the Fields Medal in 1982. Career Alain Connes attended high school at in ... | Wikipedia:Alain Connes |
was elected member of several foreign academies and societies, including the Royal Danish Academy of Sciences and Letters in 1980, the Norwegian Academy of Science and Letters in 1983, the American Academy of Arts and Sciences in 1989, the London Mathematical Society in 1994, the Canadian Academy of Sciences in 1995 (i... | Wikipedia:Alain Connes |
million The Afroasiatic languages (also known as Afro-Asiatic, Afrasian, Hamito-Semitic, or Semito-Hamitic) are a language family (or "phylum") of about 400 languages spoken predominantly in West Asia, North Africa, the Horn of Africa, and parts of the Sahara and Sahel. Over 500 million people are native speakers of an... | Wikipedia:Afroasiatic languages |
frequently used in the scholarship of various other languages, such as German. Several issues with the label Hamito-Semitic have led many scholars to abandon the term and criticize its continued use. One common objection is that the Hamitic component inaccurately suggests that a monophyletic | Wikipedia:Afroasiatic languages |
scholarship of various other languages, such as German. Several issues with the label Hamito-Semitic have led many scholars to abandon the term and criticize its continued use. One common objection is that the Hamitic component inaccurately suggests that a monophyletic "Hamitic" branch exists alongside Semitic. In addi... | Wikipedia:Afroasiatic languages |
the past, Berber languages were spoken throughout North Africa except in Egypt; since the 7th century CE, however, they have been heavily affected by Arabic and have been replaced by it in many places. There are two extinct languages potentially related to modern Berber. The first is the Numidian language, represented ... | Wikipedia:Afroasiatic languages |
Aroid), with the latter more influenced by the Nilotic languages; it is unclear whether the Dizoid group of Omotic languages belongs to the Northern or Southern group. The two Omotic languages with the most speakers are Wolaitta language A majority of specialists consider Omotic to constitute a sixth branch of Afroasia... | Wikipedia:Afroasiatic languages |
that the near-extinct Ongota language is a separate branch of Afroasiatic; however, this is only one of several competing theories. About half of current scholarly hypotheses on Ongota'sorigins align it with Afroasiatic in some way. * Robert Hetzron proposed that Beja language * The extinct Meroitic language has been p... | Wikipedia:Afroasiatic languages |
which features are innovative and which are inherited from Proto-Afroasiatic produces radically different trees, as can be seen by comparing the trees produced by Ehret and Igor Diakonoff. Responding to the above, Tom Güldemann criticizes attempts at finding subgroupings based on common or lacking morphology by arguing... | Wikipedia:Afroasiatic languages |
century CE by the Hebrew grammarian and physician Judah ibn Kuraish An important development in the history of Afroasiatic scholarship – and the history of African linguistics – was the creation of the "Hamites The first scholar to question the existence of "Hamitic languages" was Marcel Cohen in 1924, with skepticism ... | Wikipedia:Afroasiatic languages |
the youngest end of this range still makes Afroasiatic the oldest proven language family. Contrasting proposals of an early emergence, Tom Güldemann has argued that less time may have been required for the divergence than is usually assumed, as it is possible for a language to rapidly restructure due to language contac... | Wikipedia:Afroasiatic languages |
ly that this is inherited from proto-Afroasiatic. All Afroasiatic languages | Wikipedia:Afroasiatic languages |
important role in Afroasiatic, especially in Chadic; it can affect the form of affixes attached to a word. Consonant systems Several Afroasiatic languages have large consonant inventories, and it is likely that this is inherited from proto-Afroasiatic. All Afroasiatic languages contain stop consonant Most, if not all b... | Wikipedia:Afroasiatic languages |
and seven), but the number of phonetic vowels can be much larger. The quality of the underlying vowels varies considerably by language; the most common vowel throughout Afroasiatic is schwa. In the different languages, central vowels are often inserted to break up consonant clusters (a form of epenthesis). Various Semi... | Wikipedia:Afroasiatic languages |
A widely attested feature in AA languages is a consonantal structure into which various vocalic "templates" are placed. This structure is particularly visible in the verbs, and is particularly noticeable in Semitic. Besides for Semitic, vocalic templates are well attested for Cushitic and Berber, where, along with Chad... | Wikipedia:Afroasiatic languages |
e, a "construct state", and a "pronominal state". The construct state is used when a noun becomes unstressed as the first element of a compound, whereas the pronominal state | Wikipedia:Afroasiatic languages |
and Egyptian grammar also refers to nouns having a "free" (absolute) state, a "construct state", and a "pronominal state". The construct state is used when a noun becomes unstressed as the first element of a compound, whereas the pronominal state is used when the noun has a suffixed possessive pronoun. Berber instead c... | Wikipedia:Afroasiatic languages |
Chadic, with masculine K also appearing in Omotic. The feminine marker T is one of the most consistent aspects across the different branches of AA. Verb forms Tenses, aspects, and moods (TAMs) There is no agreement | Wikipedia:Afroasiatic languages |
be found in Cushitic, Chadic, with masculine K also appearing in Omotic. The feminine marker T is one of the most consistent aspects across the different branches of AA. Verb forms Tenses, aspects, and moods (TAMs) There is no agreement about which tense-aspect-mood "Prefix conjugation" Conjugation of verbs using prefi... | Wikipedia:Afroasiatic languages |
derivationA prefix in m- is the most widely attested affix in AA that is used to derive nouns, and is one of the features Joseph Greenberg used to diagnose membership in the family. It forms agent nouns, place nouns, and instrument nouns. In some branches, it can also derive abstract nouns and participles. Omotic, mean... | Wikipedia:Afroasiatic languages |
pronouns. They can occur together with subject pronouns but cannot fulfill an object function. Also common are dependent/affix pronouns (used for direct objects and to mark possession). For most branches, the first person pronouns contain a nasal consonant (n, m), whereas the third person displays a sibilant consonant ... | Wikipedia:Afroasiatic languages |
individual branches, but instead comparing words in the individual languages. Nevertheless, both dictionaries agree on some items and some proposed cognates are uncontroversial. Such cognates tend to rely on relatively simple sound correspondences. (possibly) Hausa bùgaː 'to hit, strike Hausa halshe(háɽ.ʃè) 'tongue'; | Wikipedia:Afroasiatic languages |
Chicago: The Oriental Institute, 2007, p.139–145. * A comparison of Orel-Stolbova's and Ehret's Afro-Asiatic reconstructions * "Is Omotic Afro-Asiatic?" by Rolf Theil (2006) * Afro-Asiatic webpage of Roger Blench (with family tree). Category:Afroasiatic languages Category:Afroasiatic peoples Category:Language | Wikipedia:Afroasiatic languages |
Oriental Civilization 60. Chicago: The Oriental Institute, 2007, p.139–145. * A comparison of Orel-Stolbova's and Ehret's Afro-Asiatic reconstructions * "Is Omotic Afro-Asiatic?" by Rolf Theil (2006) * Afro-Asiatic webpage of Roger Blench (with family tree). Category:Afroasiatic languages Category:Afroasiatic peoples C... | Wikipedia:Afroasiatic languages |
In mathematics and statistics, the arithmetic mean ( ), arithmetic average, or just the mean or average (when the context is clear) is the sum of a collection of numbers divided by the count of numbers in the collection. The collection is often a set of results from an experiment, an observational study, or a Survey (s... | Wikipedia:Arithmetic mean |
as “meane” the midpoint of a lowest and highest number, not quite the arithmetic mean. In 1668, a person known as “DB” was quoted in the Transactions of the Royal Society describing “taking the mean” of five values: Motivating properties The arithmetic mean has several properties that make it interesting, especially as... | Wikipedia:Arithmetic mean |
a person known as “DB” was quoted in the Transactions of the Royal Society describing “taking the mean” of five values: Motivating properties The arithmetic mean has several properties that make it interesting, especially as a measure of central tendency. These include: *If numbers x_1,,x_n have mean x, then (x_1-x)++(... | Wikipedia:Arithmetic mean |
mean may be contrasted with the median. The median is defined such that no more than half the values are larger, and no more than half are smaller than it. If elements in the data arithmetic progression There are applications of this phenomenon in many fields. For example, since the 1980s, the median income in the Unit... | Wikipedia:Arithmetic mean |
possible values can be described by integrating a continuous probability distribution across this range, even when the naive probability for a sample number taking one certain value from infinitely many is zero. In this context, the analog of a weighted average, in which there are infinitely many possibilities for the ... | Wikipedia:Arithmetic mean |
the modular distance between 1° and 359° is 2°, not 358°). Symbols and encoding The arithmetic mean is often denoted by a bar (Vinculum (symbol) In some document formats (such as PDF), the symbol may be replaced by a "¢" (Euro coins See also * Fréchet mean *Generalized mean *Inequality of arithmetic and geometric means... | Wikipedia:Arithmetic mean |
Abacı -like abacus representing An abacus ( abaci or abacuses), also called a counting frame, is a hand-operated calculating tool which was used from ancient times in the ancient Near East, Europe, China, and Russia, until the adoption of the Hindu–Arabic numeral system. An abacus consists of a two-dimensional array of... | Wikipedia:Abacus |
are thought to have been used as counters. However, wall depictions of this instrument are yet to be discovered. Persia At around 600BC, Persians first began to use the abacus, during the Achaemenid Empire. Under the Parthian Empire Greece The earliest archaeological evidence for the use of the Greek abacus dates to th... | Wikipedia:Abacus |
abacus, also known as the suanpan (算盤/算盘, lit. "calculating tray"), comes in various lengths and widths, depending on the operator. It usually has more than seven rods. There are two beads on each rod in the upper deck and five beads each in the bottom one, to represent numbers in a bi-quinary coded decimal-like system... | Wikipedia:Abacus |
in parts separated by a bar or intermediate cord. In the left part were four beads. Beads in the first row have unitary values (1, 2, 3, and 4), and on | Wikipedia:Abacus |
; and on the other hand 0, 1, 2, and 3 were used. Note the use of zero at | Wikipedia:Abacus |
Peninsula that also computed calendar data. This was a finger abacus, on one hand, 0, 1, 2, 3, and 4 were used; and on the other hand 0, 1, 2, and 3 were used. Note the use of zero at the beginning and end of the two cycles. The quipu of the Incas was a system of colored knotted cords used to record numerical data, lik... | Wikipedia:Abacus |
and 6th wire, corresponding to the color change between the 5th and the 6th bead on each wire, suggests the latter use. Teaching multiplication, e.g. 6 times 7, may be represented by shifting 7 beads on 6 wires. The red-and-white abacus is used in contemporary primary schools for a wide range of number-related lessons.... | Wikipedia:Abacus |
of Chinese, Japanese and Russian abaci * An atomic-scale abacus * Examples of Abaci * Aztex Abacus * Indian Abacus * Abacus Course Category:Abacus Category:Mathematical tools Category:Chinese mathematics Category:Egyptian mathematics Category:Greek mathematics Category:Indian mathematics Category:Japanese mathematics C... | Wikipedia:Abacus |
Acidity (novelette) , a typical metal, reacting with hydrochloric acid, a typical acid An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid–base theory The first category of acids are the proton donors, or Brønsted–Lowry acid–base theory Aqueous Arrhen... | Wikipedia:Acid |
example, HCl has chloride as its anion, so the hydro- prefix is used, and the -ide suffix makes the name take the form hydrochloric acid. Classical naming system: In the IUPAC naming system, "aqueous" is simply added to the name of the ionic compound. Thus, for hydrogen chloride, as an acid solution, the IUPAC name is ... | Wikipedia:Acid |
) and lose a second to form carbonate anion (CO). Both Ka | Wikipedia:Acid |
large Ka1 for the first dissociation makes sulfuric a strong acid. In a similar manner, the weak unstable carbonic acid can lose one proton to form bicarbonate anion ) and lose a second to form carbonate anion (CO). Both Ka values are small, but Ka1 > Ka2 . A triprotic acid (H3A) can undergo one, two, or three dissocia... | Wikipedia:Acid |
+ [H+]K_1 + K_1 K_2 +[HA^-]+[A^ 2-] \\ _A^ 2- & K_1 K_2 + [H+]K_1 + K_1 K_2 ] +[A^ 2-] align A plot of these fractional concentrations against pH, for given K1 and K2, is known as a Bjerrum plot. A pattern is observed in the above equations and can be expanded to the general n -protic acid that has been deprotonated i ... | Wikipedia:Acid |
a Bjerrum plot. A pattern is observed in the above equations and can be expanded to the general n -protic acid that has been deprotonated i -times: : _ A^i- [ H+]^n-i _j 0^iK_j _ i 0^n [ [H+]^n-i _j 0^iK_j ] where K0 1 and the other K-terms are the dissociation constants for the acid. Neutralization (in beaker (glasswa... | Wikipedia:Acid |
an aqueous solution, an acid–base titration is commonly performed. A strong base solution with a known concentration, usually NaOH or KOH, is added to neutralize the acid solution according to the color change of the indicator with the amount of base added. The titration curve of an acid titrated by a base has two axes... | Wikipedia:Acid |
base, it can resist pH changes when base is added until the next equivalent points. Applications of acids In industry Acids are fundamental reagents in treating almost all processes in modern industry. Sulfuric acid, a diprotic acid, is the most widely used acid in industry, and is also the most-produced industrial che... | Wikipedia:Acid |
alter their taste and serve as preservatives. Phosphoric acid, for example, is a component of cola drinks. Acetic acid is used in day-to-day life as vinegar. Citric acid is used as a preservative in sauces and pickles. Carbonic acid is one of the most common acid additives that are widely added in soft drinks. During t... | Wikipedia:Acid |
acid (HFO), the only known oxoacid for fluorine. * Sulfuric acid (H2SO4) * Fluorosulfuric | Wikipedia:Acid |
t union of a carbonyl group and a hydroxyl group. In vinylogous carboxylic acids, a carbon-carbon double bond separates the carbonyl and hydroxyl groups. * Ascorbic acid Nucleic acids * DNA * RNA References * Listing of strengths of common acids and bases * * External links * Curtipot: Acid–Base equilibria diagrams, pH... | Wikipedia:Acid |
, demonstrating the viscosity of bitumen Bitumen ( , ) is an immensely viscosity About 70% of annual bitumen production is destined for road surface In material sciences and engineering, the terms asphalt and bitumen are often used interchangeably and refer both to natural and manufactured forms of the substance, altho... | Wikipedia:Bitumen |
it thus seems likely that the name itself was expressive of this application. Specifically, Herodotus mentioned that bitumen was brought to Babylon to build its gigantic fortification wall. From the Greek, the word passed into late Latin, and thence into French (asphalte) and English ("asphaltum" and "asphalt"). In Fre... | Wikipedia:Bitumen |
materials were deposited by water and buried hundreds of metres deep at the diagenesis Composition Normal composition The components of bitumen include four main classes of compounds: * Naphthene aromatics (naphthalene), consisting of partially hydrogenated polycyclic aromatic compounds * Polar aromatics, consisting of... | Wikipedia:Bitumen |
bitumen. See also * Asphalt plant * Asphaltene * Bioasphalt * Bitumen-based fuel * Bituminous coal * Bituminous rocks * Blacktop * Cariphalte * Duxit * Macadam * Oil sands * Pitch drop experiment * Pitch (resin) * Road surface * Tar * Tarmacadam * Sealcoat * Stamped asphalt Notes References Sources * . * * External lin... | Wikipedia:Bitumen |
astronaut Bruce McCandless II using a Manned Maneuvering Unit outside on shuttle mission STS-41-B in 1984 An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a List of human spaceflight programs "Astronaut" technically applies to all human sp... | Wikipedia:Astronaut |
kilometers (about 62.1 miles) and he did it two times, becoming the first person in space twice. , the man with the longest cumulative time in space is Oleg Kononenko, who has spent over 1100 days in space. Peggy Whitson Terminology In 1959, when both the United States and Soviet Union were planning, but had yet to lau... | Wikipedia:Astronaut |
astronauts and cosmonauts in general, while (, "navigating celestial-heaven personnel") is used for Chinese astronauts. Here, (, literally "heaven-navigating", or spaceflight) is strictly defined as the navigation of outer space within the local star system, i.e. Solar System. The phrase (, "spaceman") is often used in... | Wikipedia:Astronaut |
space flight safety, is considered a commercial astronaut by the Federal Aviation Administration * one who flies to the International Space Station as part of a "privately funded, dedicated commercial spaceflight on a commercial launch vehicle dedicated to the mission ... to conduct approved commercial and marketing ac... | Wikipedia:Astronaut |
a 15-minute sub-orbital flight aboard ''Mercury-Redstone 3 Cosmonaut Alexei Leonov was the first person to conduct an extravehicular activity (EVA), (commonly called a "spacewalk"), on 18 March 1965, on the Soviet Union's Voskhod 2 mission. This was followed two and a half months later by astronaut Ed White (astronaut)... | Wikipedia:Astronaut |
astronaut on its own spacecraft, the Shenzhou 5. Age milestones The youngest person to reach space is Oliver Daemen, who was 18 years and 11 months old when he made a Sub-orbital spaceflight The oldest person to reach space is William Shatner, who was 90 years old when he made a suborbital spaceflight on Blue Origin NS... | Wikipedia:Astronaut |
syndrome # Dennis Tito (American): 28 April – 6 May 2001 # Mark Shuttleworth (South African): 25 April – 5 May 2002 # Gregory Olsen (American): 1–11 October 2005 # Anousheh Ansari (Iranian / American): 18–29 September 2006 # Charles Simonyi (Hungarian / American): 7–21 April 2007, 26 March – 8 April 2009 # Richard Garr... | Wikipedia:Astronaut |
* The candidate must also have skills in leadership, teamwork and communications. The master'sdegree requirement can also be met by: * Two years of work toward a doctoral program in a related science, technology, engineering or math field. * A completed Doctor of Medicine or Doctor of Osteopathic Medicine degree. * Com... | Wikipedia:Astronaut |
school students. It is anticipated that remote guided ultrasound will have application on Earth in emergency and rural health A 2006 Space Shuttle experiment found that Salmonella typhimurium, a bacterium that can cause food poisoning, became more virulent when cultivated in space. More recently, in 2017, bacteria were... | Wikipedia:Astronaut |
centers. The study conducted by Moscow Institute of Physics and Technology (MIPT) concluded this after they observed that mice exposed to neutron and gamma radiation did not impact the rodents' intellectual capabilities. A 2020 clinical trial Food and drink An astronaut on the International Space Station requires about... | Wikipedia:Astronaut |
consisting of a statuette titled Fallen Astronaut on the surface of the Moon during his 1971 Apollo 15 mission, along with a list of the names of eight of the astronauts and six cosmonauts known at the time to have died in service. The Space Mirror Memorial, which stands on the grounds of the Kennedy Space Center Visit... | Wikipedia:Astronaut |
The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs),. The American Chemical Society (ACS) has used the spelling cesium since 1921, following ''Webster's Third New International Dictionary''. The alkali metals are all shiny, hardness All of the discove... | Wikipedia:Alkali metal |
potassium hydroxide) by the use of electrolysis of the molten salt with the newly invented voltaic pile. Previous attempts at electrolysis of the aqueous salt were unsuccessful due to potassium'sextreme reactivity. Later that same year, Davy reported extraction of sodium from the similar substance caustic soda (NaOH, l... | Wikipedia:Alkali metal |
This rule argues that elements with odd atomic numbers have one unpaired proton and are more likely to capture another, thus increasing their atomic number. In elements with even atomic numbers, protons are paired, with each member of the pair offsetting the spin of the other, enhancing stability. All the alkali metals... | Wikipedia:Alkali metal |
than the elements in any other group (periodic table) In aqueous solution, the alkali metal ions form metal ions in aqueous solution Lithium The chemistry of lithium shows several differences from that of the rest of the group as the small Li+ cation chemical polarity Lithium fluoride is the only alkali metal halide th... | Wikipedia:Alkali metal |
electrons will not be attracted as close to the chlorine atom as before because the lithium atom is smaller, making the electron pair more strongly attracted to the closer effective nuclear charge from lithium. Hence, the larger alkali metal atoms (further down the group) will be less electronegative as the bonding pai... | Wikipedia:Alkali metal |
ely to the hydroxides when in contact with water. and several brightly | Wikipedia:Alkali metal |
the structure (RLi)xwhere R is the organic group. As the | Wikipedia:Alkali metal |
nd K can react with acetylene to give acetylides. :2 Li \ + \ 2 C \ \ Li2C2 :2 Na \ + \ 2 C2H2 \ ->[150 \ ^ oC ] \ 2 NaC2H \ + \ H2 :2 Na \ + \ 2 NaC2H \ ->[220 \ ^ oC ] \ 2 | Wikipedia:Alkali metal |
ave sometimes been called "pseudo-alkali metals". These substances include some elements and many more polyatomic ions; the polyatomic | Wikipedia:Alkali metal |
Many other substances are similar to the alkali metals in their tendency to form monopositive cations. Analogously to the pseudohalogens, they have sometimes been called "pseudo-alkali metals". These substances include some elements and many more polyatomic ions; the polyatomic ions are especially similar to the alkali... | Wikipedia:Alkali metal |
chloride. The ammonium ion () has very similar properties to the heavier alkali metals, acting as an alkali metal intermediate between potassium and rubidium, and is often considered a close relative. Ammonium is expected to behave stably as a metal ( ions in a sea of delocalised electrons) at very high pressures (thou... | Wikipedia:Alkali metal |
idium and caesium also increased correspondingly. most francium is synthesised in | Wikipedia:Alkali metal |
methods: acid digestion, alkaline decomposition, and direct reduction. Both metals are produced as by-products of lithium production: after 1958, when interest in lithium'sthermonuclear properties increased sharply, the production of rubidium and caesium also increased correspondingly. most francium is synthesised in t... | Wikipedia:Alkali metal |
halocarbons, plastics, and moisture. They also react with carbon dioxide and carbon tetrachloride, so that normal fire extinguishers are counterproductive when used on alkali metal fires. Experiments are usually conducted using only small quantities of a few grams in a fume hood. Small quantities of lithium may be disp... | Wikipedia:Alkali metal |
caesium tends to substitute potassium in the body, but is significantly larger and is therefore a poorer substitute. Excess caesium can lead to hypokalemia, arrhythmia, and acute cardiac arrest, but such amounts would not ordinarily be encountered in natural sources. As such, caesium is not a major chemical environment... | Wikipedia:Alkali metal |
The atomic number or nuclear charge number (symbol Z) of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number ('''np') or the number of protons found in the nucleus of every atom of that element. The atomic number can be ... | Wikipedia:Atomic number |
the word (and its English equivalent atomic number) come into common use in this context. The rules above do not always apply to exotic atoms which contain short-lived elementary particles other than protons, neutrons and electrons. Notation . Atomic number is the number of protons, and therefore also the total positiv... | Wikipedia:Atomic number |
and a natural number for each element , creator of the periodic table. The periodic table of elements creates an ordering of the elements, and so they can be numbered in order. Dmitri Mendeleev arranged his first periodic tables (first published on March 6, 1869) in order of atomic weight ("Atomgewicht"). However, in c... | Wikipedia:Atomic number |
arithmetic progression. This led to the conclusion (Moseley's law) that the atomic number does closely correspond (with an offset of one unit for K-lines, in Moseley'swork) to the calculated electric charge of the nucleus, i.e. the element number Z. Among other things, Moseley demonstrated that the lanthanide series (f... | Wikipedia:Atomic number |
'sillustration of the Caterpillar (Alice's Adventures in Wonderland) Ambiguity is the type of meaning (linguistics) The concept of ambiguity is generally contrasted with vagueness. In ambiguity, specific and distinct interpretations are permitted (although some may not be immediately obvious), whereas with vague inform... | Wikipedia:Ambiguity |
have no misunderstanding about what was meant to be conveyed. An exception to this could include a politician whose "weasel words" and obfuscation are necessary to gain support from multiple Electoral district More problematic are words whose multiple meanings express closely related concepts. "Good", for example, can ... | Wikipedia:Ambiguity |
are called phonological ambiguities, where there is more than one way to compose a set of sounds into words. For example, "ice cream" and "I scream". Such ambiguity is generally resolved according to the context. A mishearing of such, based on incorrectly resolved ambiguity, is called a mondegreen. Philosophy Philosoph... | Wikipedia:Ambiguity |
as is the relation of mind and body, and part and whole. In Heidegger'sphenomenology, Dasein is always in a meaningful world, but there is always an underlying background for every instance of signification. Thus, although some things may be certain, they have little to do with Dasein'ssense of care and existential anx... | Wikipedia:Ambiguity |
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Dataset Description
This dataset contains 348,854 Wikipedia articles
Dataset Structure
The dataset follows a simple structure with two fields:
text: The content of the Wikipedia articlesource: The source identifier (e.g., "Wikipedia:Albedo")
Format
The dataset is provided in JSONL format, where each line contains a JSON object with the above fields.
Example:
{
"text": "Albedo is the fraction of sunlight that is reflected by a surface...",
"source": "Wikipedia:Albedo"
}
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