**An Easy Method for Constructing Dot Structures - Example: The Dicarbide ion C**_{2}^{-2}
A

**simple procedure**for writing**Lewis structures**is given in a previous article entitled “Lewis Structures and the Octet Rule”.
Several worked examples relevant to this procedure were given in previous posts please see the Sitemap - Table of Contents (Lewis Electron Dot Structures).

Let us consider the case of

**C**_{2}^{-2}.__Step 1__: Connect the atoms with single bonds.

Fig. 1: Connecting the atoms of C_{2}^{-2} with single bonds
(Step 1 of the method) |

__Step 2__: Calculate the # of electrons in π bonds (multiple bonds) using

**formula (1)**:

Where n in this
case is 2 since

**C**consists of 2 atoms._{2}^{-2}
Calculate the number of the

Where V = 2*4 – (-2) = 10

**valence electons**(V) of**C**:_{2}^{-2}Where V = 2*4 – (-2) = 10

Therefore, P = 6n
+ 2 – V = 6 *2 + 2 – 10 = 4

**Therefore, there are either 2 double bonds or 1 triple bond.**
The structure in
Figure 1 cannot have 2 double bonds. The only possibility is 1 triple bond.

__Step 3 & 4__: The Lewis

**dot structure**of

**C**is as follows:

_{2}^{-2}Fig.1: Lewis structure of dicarbide C2-2 |

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