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For CCl4, describe the central atom and number of unshared pairs of electrons, if any,...

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tdj4325 | Salutatorian

Posted July 6, 2012 at 6:43 PM via web

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For CCl4, describe the central atom and number of unshared pairs of electrons, if any, in the molecule.

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted July 7, 2012 at 2:10 AM (Answer #1)

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Carbon tetrachloride is a tetrahedral molecule formed when carbon combines with 4 chlorine atoms.

The carbon atom has 4 electrons in its outermost electron shell. Each chlorine atom has 7 electrons in its outermost electron shell. When one electron is shared by carbon with each of the four chlorine atoms all the 5 atoms achieve a stable outermost electron shell configuration of a noble gas.

As carbon which is the central atom in CCl4 has to share all four of it electrons with each of the 4 chlorine atoms there are no unshared pairs of electrons.

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llltkl | College Teacher | Valedictorian

Posted July 22, 2012 at 5:27 PM (Answer #2)

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Carbon tetrachloride is a tetrahedral molecule formed when carbon combines with 4 chlorine atoms through single covalent bonds.

The carbon atom has 4 electrons in its valence (outermost) electron shell. Each chlorine atom has 7 electrons in its valence (outermost) electron shell, out of which one is shared with carbon. The other six electrons sit idle atop each chlorine and are termed unpaired electrons. As a result of such sharing, all the 5 atoms achieve a stable valence (outermost) electron shell configuration of a noble gas i.e 8 electrons.

As carbon is the central atom and it has to share all four of its electrons with the four chlorine atoms there are no unshared pairs of electrons over it.

Though there are three unshared pairs of electrons over each of the four chlorine atoms. Hence strictly speaking, the molecule shall have 4x3 +0 = 12 pairs of unpaired electrons in total. These electrons, however, play no role in determining overall molecular geometry as they are not seated atop the central atom.

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