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The lewis dot structure for ions normally shows the constituent elements, with their valence electrons, in brackets, with the electric charge shown outside the bracket. For instance, the calcium ion would be shown as
Please note that calcium does not have one valence electron; it has two, and would thus form a +2 ion.
Silicon has 4 valence electrons, and each oxygen has 6, for a total of 22. By using the distribution method, we can determine that one of the possible lewis dot structures for SiO3 is;
:O: = Si - :Ö:
(since I can't really draw 3-dimensionally on here, the electron pairs should be redistributed more evenly over the "surface" of the oxygen atoms.)
This polyatomic ion has a charge of -2, so it balances with a single calcium ion. The lewis dot structure for this arrangement would look something like:
[Ca] +2 :O: = Si - :Ö:
[ | ] -2
with a bracket drawn around the entire SiO3 ion.
Correction: The cation Calcium (Ca) has 2 valence electrons as indicated by its position in column 2 of the Periodic Table, thus it carries a charge of +2
On the other hand, SiO3 is an "oxyanion" and it's stoichiometry and charge are as follows:Stoichiometry: Si + 2 O +2×½ O = SiO3Charge: +4 + (2 × − 2) + (2 × (½ × −2)) = −2
Most silicate minerals are formed via a decondensation reaction in which silica (SiO2) reacts with a basic oxide, in this example:
SiO2 (acid) + CaO (base) → CaSiO3
With this new info, see if you can know draw the Lewis structure for CaSiO3
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