Why does Cl change in price and are all odd numbers?
Cl shows ionic bond - 1 valence (NaCl), *** valence bond - 1 valence (HCl), *** valence bond 0 valence (Cl2), *** valence bond + 1 valence ( HClO), *** valence bond + 3 valence (HClO2), *** valence bond + 5 valence (HClO3), *** valence bond + 7 valence (HClO4)
The structure determines the properties, but , the atomic structure of Cl given in the high school textbook (page 126 of the textbook: Cl’s electron shell arrangement is 2, 8, 7) is not enough to explain the above facts, and it is necessary to rely on the Cossel atomic model.
Cl is the 17th element, with 17 extranuclear electrons, arranged as
1S2; 2S2, 2P2, 2P2, 2P2; 3S2, 3P2, 3P2, 3P1
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The third layer is the outermost layer, with a half-empty P orbital on which there is an "unmarried" electron (scientific name "lone pair electron") - 3P1,
( 1) Pull in an external electron to use alone, filling all its orbits (...3S2, 3P2, 3P2, 3P1+1) and reaching a stable state. At this time, Cl shows an ionic bond -1 valence, for example, NaCl < /p>
(2) Provide this "unmarried" electron to form a "useful" electron pair with an external electron, which is equivalent to filling all its own orbits (...3S2, 3P2, 3P2, 3P1 +1), reach a stable state, and at the same time bring the "*** electron pair" closer to yourself. At this time, Cl shows a *** valence bond -1 valence, such as HCl
(3) Two When Cl meet, they each provide this "unmarried" electron to form a "primary" electron pair, which is equivalent to filling all their orbits (...3S2, 3P2, 3P2, 3P1+1) and reaching a stable state. This is Cl2.
At this time, the "*** electron pair" is impartial, just in the middle of the two Cl, and Cl shows the *** valence bond 0 valence.
(4) Cl and O meet, Cl provides "unmarried" electrons 3P1, O (1S2; 2S2, 2P2, 2P1, 2P1) provides "unmarried" electrons 2P1, forming an electron pair ,
Since the electronegativity of O is greater than that of Cl ("A Concise Tutorial on Inorganic Chemistry": the electronegativity of O is 3.5 and the electronegativity of Cl is 3.0), we use electron pairs for "***" "Bring O closer and away from Cl. At this time, Cl shows *** valence bond + 1 valence,
For example
H—O—Cl
This The abbreviation of the substance is HClO, and it is named hypochlorous acid.
(5) When Cl and O meet, Cl provides electrons 3P1, 3P2*** 3 electrons, which form ***electrons with O respectively. Yes,
Since the electronegativity of O is greater than that of Cl, the "positive electron pair" is pulled closer to O and away from Cl. At this time, Cl shows a positive valence bond + 3 valence, < /p>
For example
H—O—Cl==O
This substance is abbreviated as HClO2 and named chlorous acid,
( 6) When Cl and O meet, Cl provides electrons 3P1, 3P2, and 3P2 to form ***electron pairs with O respectively.
Since the electronegativity of O is greater than that of Cl, Just pull the "*** electron pair" closer to O and away from Cl. At this time, Cl shows *** valence bond + 5 valence,
For example
H—O— Cl—2O
This substance is abbreviated as HClO3 and named chloric acid.
(7) Cl and O meet, Cl provides electrons 3P1, 3P2, 3P2, 3P2*** 7 electrons, forming primary electron pairs with O respectively,
Since the electronegativity of O is greater than that of Cl, the "positive electron pair" is pulled closer to O and away from Cl. At this time, Cl shows a positive valence bond + 7 valence,
For example< /p>
H—O—Cl—3O
This substance is abbreviated as HClO4 and named perchloric acid.