| 单词 | double bond |
| 例句 | A fat is monounsaturated if it contains just one double bond among its carbon atoms. Coconut oil: are the health benefits a big fat lie? 2017-07-09T04:00:00Z In an unsaturated fat molecule, one or more carbon atoms are linked by double bonds. Coconut oil: are the health benefits a big fat lie? 2017-07-09T04:00:00Z When the hydrocarbon chain contains a double bond, the fatty acid is an unsaturated fatty acid. Concepts of Biology 2013-04-25T00:00:00Z A green appearance for comets is not uncommon and is usually the result of breakdown of a reactive molecule called dicarbon - two carbon atoms joined together by a double bond. Newly discovered green comet comes close to Earth 2023-01-31T05:00:00Z Meanwhile tiny structural changes—even shifting the location of one double bond—can dramatically alter a scent. AI Predicts What Chemicals Will Smell like to a Human 2022-10-27T04:00:00Z The actual distribution of electrons in each of the nitrogen-oxygen bonds in is the average of a double bond and a single bond. Chemistry 2019-02-14T00:00:00Z In contrast to unsaturated fats, triglycerides without double bonds between carbon atoms are called saturated fats, meaning that they contain all the hydrogen atoms available. Biology for AP Courses 2022-06-09T00:00:00Z The double bond causes a bend or a “kink” that prevents the fatty acids from packing tightly, keeping them liquid at room temperature. Concepts of Biology 2013-04-25T00:00:00Z If there is at least one carbon-carbon double bond, the fatty acid is unsaturated. Miller & Levine Biology 2018-01-01T00:00:00Z Each atom might form either a double bond on each side — meaning the adjacent atoms share two electrons — or a triple bond on one side and a single bond on the other. Chemists make first-ever ring of pure carbon 2019-08-14T04:00:00Z One oxygen atom must have a double bond to carbon to complete the octet on the central atom. Chemistry 2019-02-14T00:00:00Z Saturated triglycerides contain single bonds and are solids at room temperature, while unsaturated triglycerides contain double bonds and are liquids at room temperature. Biology for AP Courses 2022-06-09T00:00:00Z They are a type of polyunsaturated fat and are called omega-3 fatty acids because the third carbon from the end of the fatty acid participates in a double bond. Concepts of Biology 2013-04-25T00:00:00Z Lipids with fatty acids containing more than one double bond are polyunsaturated. Miller & Levine Biology 2018-01-01T00:00:00Z Some PFASs now contain a double bond, or a chlorine or hydrogen atom in place of a fluorine. Tainted water: the scientists tracing thousands of fluorinated chemicals in our environment 2019-02-05T05:00:00Z All oxygen atoms, however, are equivalent, and the double bond could form from any one of the three atoms. Chemistry 2019-02-14T00:00:00Z Saturated triglycerides contain double bonds and are liquids at room temperature, while unsaturated triglycerides contain single bond and are solids at room temperature. Biology for AP Courses 2022-06-09T00:00:00Z Convention these days is a depiction containing three double bonds. Chemists get faster on the draw It’s been transformed into a skeletal formula, a series of hexagons with single and double bond lines between them, commonly used to represent carbon and hydrogen atoms in organic chemistry. Google’s new Doodle celebrates the 100th birthday of Indian chemist Asima Chatterjee 2017-09-23T04:00:00Z The bulky groups at either end of the double bond usually point in opposite directions — a configuration called trans. The next big hit in molecule Hollywood 2017-04-25T04:00:00Z Thus a single bond has a bond order of 1, a double bond has a bond order of 2, and a triple bond has a bond order of 3. Chemistry 2019-02-14T00:00:00Z Fats with at least one double bond between carbon atoms are unsaturated fats. Biology for AP Courses 2022-06-09T00:00:00Z The double bonds create a weak link in the short alkane chains—a vulnerability that the second catalyst exploits to split the alkane chain. Catalysts could turn trash bags into fuel 2016-06-17T04:00:00Z Saturated fats are "saturated" or completely full of hydrogen, contain no double bonds and are usually solid at room temperature. Let’s 'Unsaturate' the Fat Talk 2016-04-05T04:00:00Z These atoms “bond” together using magnets that accurately portray the single bonds, double bonds and free electrons that make up the molecules of the universe. The Coolest Toys at Toy Fair 2016 2016-02-16T05:00:00Z Oxygen forms a double bond in the O2 molecule, and sulfur, selenium, and tellurium form two single bonds in various rings and chains. Chemistry 2019-02-14T00:00:00Z During this hydrogenation process, double bonds in the cis- conformation in the hydrocarbon chain may be converted to double bonds in the trans- conformation; unfortunately, trans fats have been shown to contribute to heart disease. Biology for AP Courses 2022-06-09T00:00:00Z The newly free chemical handles bond to each other, forming a double bond between the neighboring carbon atoms. Catalysts could turn trash bags into fuel 2016-06-17T04:00:00Z Unsaturated fats are not "saturated" or filled with hydrogen, contain double bonds and are usually liquid at room temperature. Let’s 'Unsaturate' the Fat Talk 2016-04-05T04:00:00Z "We included a double bond in the molecules," says Shankland, "so it reacts very quickly in the atmosphere, with a half-life of weeks." How 1970s deodorant is still doing harm - BBC News 2015-06-05T04:00:00Z To move closer to an octet for nitrogen, we take one of the lone pairs from oxygen and use it to form a NO double bond. Chemistry 2019-02-14T00:00:00Z When a fatty acid has no double bonds, it is known as a saturated fatty acid because no more hydrogen may be added to the carbon atoms of the chain. Biology for AP Courses 2022-06-09T00:00:00Z Consider the quintessential prototype aromatic hydrocarbon, benzene, drawn with its alternating double bonds. Truth and beauty in chemistry 2013-01-25T00:15:10.973Z Since PUFAs are named based on the position of the double bond closest to that omega carbon, they are often called "omega-3" or "omega-6" fats. The Alpha and the Omegas 2012-11-16T22:05:00Z For silicon however, there are more electron orbitals in the way, the entire atom is bigger, and it is almost impossible for the outer orbitals to get close enough to form a double bond. Shine on you crazy diamond: why humans are carbon-based lifeforms 2012-11-12T12:45:03.553Z However, the B–F bonds are slightly shorter than what is actually expected for B–F single bonds, indicating that some double bond character is found in the actual molecule. Chemistry 2019-02-14T00:00:00Z Cis and trans indicate the configuration of the molecule around the double bond. Biology for AP Courses 2022-06-09T00:00:00Z In reality there are no double bonds, not even dotted lines representing partial double bonds. Truth and beauty in chemistry 2013-01-25T00:15:10.973Z The number refers to the position of the double bond closest to one end of the fat molecule, known as the "methyl'" end. The Alpha and the Omegas 2012-11-16T22:05:00Z Carbon-carbon double bonds on the other hand form naturally and easily, and are crucial for every living organism on earth. Shine on you crazy diamond: why humans are carbon-based lifeforms 2012-11-12T12:45:03.553Z Starting with the central atom, click on the double bond to add one double bond. Chemistry 2019-02-14T00:00:00Z Each double bond may be in a cis or trans configuration. Biology for AP Courses 2022-06-09T00:00:00Z By contrast, introducing an unsaturated -CH=CH- did not alter the electron injection time, as a result of the enhanced electronic coupling through the double bond. Materials interface engineering for solution-processed photovoltaics 2012-08-15T17:22:03.163Z As expected, the distance between the boron atoms was shorter in the triple-bonded structure than in the compound with a double bond, matching closely with predicted figures. Triple-Bond: Boron Joins Elite Chemical Club 2012-06-15T19:45:05.067Z The double bond consists of two different types of bond. Shine on you crazy diamond: why humans are carbon-based lifeforms 2012-11-12T12:45:03.553Z These are complex organic molecules with long chains of carbon atoms, which contain at least one double bond between carbon atoms. Chemistry 2019-02-14T00:00:00Z During this hydrogenation process, double bonds of the cis- conformation in the hydrocarbon chain may be converted to double bonds in the trans- conformation. Biology for AP Courses 2022-06-09T00:00:00Z Beta-carotene, the familiar deep orange coloring found in sweet potatoes and carrots, illustrates this well, with 11 conjugated double bonds. Cochineal Dye Bugs Starbucks Customers 2012-04-05T17:15:00.207Z Buckyballs, as they became known colloquially, are football-shaped molecules made of 60 carbon atoms linked by single and double bonds. The 2010 Nobel prizes: Making new things 2010-10-07T11:04:00Z "There can be no doubt on that point," added Louis; "you are united to us by the double bond of vassalage and relationship." Barbarossa; An Historical Novel of the XII Century. Unsaturated hydrocarbon molecules that contain one or more double bonds are called alkenes. Chemistry 2019-02-14T00:00:00Z These are polyunsaturated fatty acids and are called omega-3 because the third carbon from the end of the hydrocarbon chain is connected to its neighboring carbon by a double bond. Biology for AP Courses 2022-06-09T00:00:00Z The old Zoroastrianism was in this respect as pure as the religion of the Jews, and thus a double bond of religious sympathy united the Hebrews and the Arians. The Seven Great Monarchies Of The Ancient Eastern World, Vol 3. (of 7): Media The History, Geography, And Antiquities Of Chaldaea, Assyria, Babylon, Media, Persia, Parthia, And Sassanian or New Persian Empire; With Maps and Illustrations. As for the girl—there was now a double bond between her and the dog. A Gentleman Vagabond and Some Others He held him fast in the double bonds of indebtedness and of gratitude, and with Jack the gratitude was by far the greater. Acton's Feud A Public School Story Four carbon atoms in the chain of butene allows for the formation of isomers based on the position of the double bond, as well as a new form of isomerism. Chemistry 2019-02-14T00:00:00Z It has three cis double bonds and, as a result, a curved shape. Biology for AP Courses 2022-06-09T00:00:00Z He had not told his people yet of the double bond which he designed to make between the two houses. Lippincott's Magazine of Popular Literature and Science Volume 17, No. 101, May, 1876 They were brought near at once to Christ and to one another: united to one another in him, in that double bond which, is the perfection at once of our duty and of our happiness. The Christian Life Its Course, Its Hindrances, And Its Helps Though with the smile of his dear face he draws mother's yearning heart to him, yet his little cries over tiny troubles weave the double bond of pity and love. The Crescent Moon Two electrons are shared in a single bond; four electrons are shared in a double bond; and six electrons are shared in a triple bond. Chemistry 2019-02-14T00:00:00Z Fatty acids may be unsaturated or saturated, depending on the presence or absence of double bonds in the hydrocarbon chain. Biology for AP Courses 2022-06-09T00:00:00Z The unhybridized p orbital on the carbon atom in the carbonyl group overlaps a p orbital on the oxygen atom to form the π bond in the double bond. Chemistry 2019-02-14T00:00:00Z Thus, we find that triple bonds are stronger and shorter than double bonds between the same two atoms; likewise, double bonds are stronger and shorter than single bonds between the same two atoms. Chemistry 2019-02-14T00:00:00Z Second-period elements, such as carbon, form very strong π bonds, which is why carbon dioxide forms small molecules with strong double bonds. Chemistry 2019-02-14T00:00:00Z CO has the strongest carbon-oxygen bond because there is a triple bond joining C and O. CO2 has double bonds. Chemistry 2019-02-14T00:00:00Z When the hydrocarbon chain contains a double bond, the fatty acid is said to be unsaturated. Biology for AP Courses 2022-06-09T00:00:00Z We can draw three possibilities for the structure: carbon in the center and double bonds, carbon in the center with a single and triple bond, and oxygen in the center with double bonds: Chemistry 2019-02-14T00:00:00Z If nitrite ions do indeed contain a single and a double bond, we would expect for the two bond lengths to be different. Chemistry 2019-02-14T00:00:00Z For example, an atom with four single bonds, a double bond, and a lone pair has an octahedral electron-group geometry and a square pyramidal molecular structure. Chemistry 2019-02-14T00:00:00Z This molecule has regions of high electron density that consist of two single bonds and one double bond. Chemistry 2019-02-14T00:00:00Z Unsaturated fatty acids have one or more double bonds. Biology for AP Courses 2022-06-09T00:00:00Z Using the standard enthalpy of formation data in Appendix G, calculate the bond energy of the carbon- sulfur double bond in CS2. Chemistry 2019-02-14T00:00:00Z The location of the double bond is identified by naming the smaller of the numbers of the carbon atoms participating in the double bond: Chemistry 2019-02-14T00:00:00Z Carbon atoms are free to rotate around a single bond but not around a double bond; a double bond is rigid. Chemistry 2019-02-14T00:00:00Z This shows us two regions of high electron density around the carbon atom—each double bond counts as one region, and there are no lone pairs on the carbon atom. Chemistry 2019-02-14T00:00:00Z A cis double bond causes a kink in the chain. Biology for AP Courses 2022-06-09T00:00:00Z This makes it possible to have two isomers of 2-butene, one with both methyl groups on the same side of the double bond and one with the methyl groups on opposite sides. Chemistry 2019-02-14T00:00:00Z We begin counting at the end of the chain closest to the double bond—in this case, from the left—the double bond spans carbons 2 and 3, so the name becomes 2-pentene. Chemistry 2019-02-14T00:00:00Z The product of the halogenation reaction will have two chlorine atoms attached to the carbon atoms that were a part of the carbon-carbon double bond: Chemistry 2019-02-14T00:00:00Z There is an O=O double bond, and each oxygen atom has eight electrons around it. Chemistry 2019-02-14T00:00:00Z The hydrogenation of oil makes the trans fat, which contains double bonds in its structure. Biology for AP Courses 2022-06-09T00:00:00Z Each of the six bonds between its carbon atoms is equivalent and exhibits properties that are intermediate between those of a C–C single bond and a double bond. Chemistry 2019-02-14T00:00:00Z When two carbon atoms form a double bond, the shape is planar, or flat. Biology for AP Courses 2022-06-09T00:00:00Z Ring structures are found in hydrocarbons, sometimes with the presence of double bonds, which can be seen by comparing the structure of cyclohexane to benzene in Figure 2.25. Biology for AP Courses 2022-06-09T00:00:00Z The presence of the double bond is signified by replacing the suffix -ane with the suffix -ene. Chemistry 2019-02-14T00:00:00Z There are no double bonds between adjacent carbon atoms. Biology for AP Courses 2022-06-09T00:00:00Z Single or double bonds may connect the carbons in the ring, and nitrogen may be substituted for carbon. Biology for AP Courses 2022-06-09T00:00:00Z Geometric isomers, on the other hand, have similar placements of their covalent bonds but differ in how these bonds are made to the surrounding atoms, especially in carbon-to-carbon double bonds. Biology for AP Courses 2022-06-09T00:00:00Z When the carbons are bound on the same side of the double bond, this is the cis configuration; if they are on opposite sides of the double bond, it is a trans configuration. Biology for AP Courses 2022-06-09T00:00:00Z When structures of butene are drawn with 120° bond angles around the sp2-hybridized carbon atoms participating in the double bond, the isomers are apparent. Chemistry 2019-02-14T00:00:00Z We know that the temperature of the environment is sensed by E. coli through the temperature-dependent confirmation of enzymes that convert a single bond in the lipid tail to a double bond, and vice versa. Biology for AP Courses 2022-06-09T00:00:00Z Saturated triglycerides contain double bonds and are solids at room temperature, while unsaturated triglycerides contain single bonds and are liquids at room temperature. Biology for AP Courses 2022-06-09T00:00:00Z Saturated triglycerides contain single bonds and are liquids at room temperature, while unsaturated triglycerides contain double bonds and are solids at room temperature. Biology for AP Courses 2022-06-09T00:00:00Z Unsaturated fatty acids may have one or more double bonds in the hydrocarbon chain. Biology for AP Courses 2022-06-09T00:00:00Z For example, halogens add to the double bond in an alkene instead of replacing hydrogen, as occurs in an alkane: Chemistry 2019-02-14T00:00:00Z Double and triple bonds change the geometry of the molecule: single bonds allow rotation along the axis of the bond, whereas double bonds lead to a planar configuration and triple bonds to a linear one. Biology for AP Courses 2022-06-09T00:00:00Z |
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