26. All atoms in the following molecules satisfy the structure with 8 electrons in the outermost layer ( )
(1) $\mathrm { BeCl } _ { 2 }$ (2) $\mathrm { PCl } _ { 5 }$ (3) $\mathrm { SF } _ { 6 }$ (4) $\mathrm { CS } _ { 2 }$ (5) $\mathrm { CH } _ { 4 }$ (6) $\mathrm { SiO } _ { 2 } ( 7 ) \mathrm { CF } _ { 2 } \mathrm { Cl } _ { 2 }$ (7) $\mathrm { SiO } _ { 2 } ( 7 ) \mathrm { CF } _ { 2 } \mathrm { Cl } _ { 2 }$ (7) $\mathrm { SiO } _ { 2 } ( 7 ) \mathrm { CF } _ { 2 } \mathrm { Cl } _ { 2 }$ (8) FORMULA_5]]
- A. A. (1) (2) (5)
- B. B. (4) (6) (7)
- C. C. (3) (4) (7)
- D. D. (3) (4) (6)
Answer: B
Solution: (1) The element beryllium in $\mathrm { BeCl } _ { 2 }$ has 2 electrons in the outermost layer with a valence of + 2, so the total number of electrons in the outermost layer is $2 + 2 = 4$, so it is wrong; (2) The number of electrons in the outermost layer of the atom phosphorus in $\mathrm { PCl } _ { 5 }$ is 5, and the valence of the element is + 5, so the total number of electrons in the outermost layer is [[[]]]. INLINE_FORMULA_3]] electrons, so it is wrong; (3) The sulfur atom in $\mathrm { SF } _ { 6 }$ has 6 electrons in the outermost layer, and the valence is + 6, so the total number of $6 + 6 = 12$ electrons in the outermost layer is wrong; (4) The number of electrons in the outermost layer of $\mathrm { CS } _ { 2 }$ is 5, and the valence is + 5, so there are a total of $6 + 6 = 12$ electrons in the outermost layer. In $\mathrm { CS } _ { 2 }$, the carbon atom has $4 + 4 = 8$ and the sulfur atom has $6 + 2 = 8$ electrons in its outermost layer, so it is correct; (5) In $\mathrm { CH } _ { 4 }$, the hydrogen atom has 2 electrons in its outermost layer, so it is wrong; (6) In $\mathrm { SiO } _ { 2 }$, the silicon atom has $\mathrm { SiO } _ { 2 }$ electrons in its outermost layer. In $\mathrm { SiO } _ { 2 }$, the silicon atom has $4 + 4 = 8$ and the oxygen atom has $6 + 2 = 8$, so it is correct; (7) The carbon atom in $\mathrm { CF } _ { 2 } \mathrm { Cl } _ { 2 }$ has $4 + 4 = 8$ and $7 + 1 = 8$ in $7 + 1 = 8$.
$4 + 4 = 8$, the number of outermost electrons of fluorine atom is $7 + 1 = 8$, and the number of outermost electrons of chlorine atom is $7 + 1 = 8$, so it is correct. Therefore, choose B.
[Eyesight] in determining whether all atoms in the molecule to meet the outermost layer of the 8-electron structure, can be based on the following steps to compare the simple, first of all, to see whether the molecule contains hydrogen or rare gas elements, these elements do not meet the 8-electron stabilization of the structure, and secondly, to see whether to write the electronic formulas, if they have been written to write the electronic formulas of the 8-electron stabilization of the structure can be met, and finally through the calculation of the judgment, the atom according to the outermost layer of the Finally, by calculation, according to the outermost layer of the atom, the absolute value of electrons + valence is calculated, and if the result is 8, then 8 electrons are satisfied, otherwise it is not satisfied. This 3-step process can reduce the amount of calculations and increase the rate of doing the problem.