Question

which of the following will have a double bond between c and c, and will have trigonal planar around c for both electron and molecular geometry? (can be any one of the c if there is more than one c) (hint: you will have to try out lewis structures drawings before you can come up with correct answer) 1) c₂h₂ 2) c₂h₄ 3) c₂h₆ 4) ch₄

Explanation:

Step1: Analyze $C_2H_2$

$C_2H_2$ has a triple - bond between the two carbon atoms ($C\equiv C$), not a double - bond. Its electron and molecular geometry around each carbon is linear.

Step2: Analyze $C_2H_4$

Draw the Lewis structure of $C_2H_4$. There is a $C = C$ double - bond. Each carbon atom has 3 regions of electron density (2 $C - H$ single bonds and 1 $C = C$ double - bond). According to VSEPR theory, the electron and molecular geometry around each carbon is trigonal planar.

Step3: Analyze $C_2H_6$

$C_2H_6$ has only single bonds ($C - C$ and $C - H$). There is no double - bond between the carbon atoms. Each carbon has a tetrahedral electron and molecular geometry.

Step4: Analyze $CH_4$

$CH_4$ has only single $C - H$ bonds. The carbon atom has 4 regions of electron density, and its electron and molecular geometry is tetrahedral.

Answer:

1. $C_2H_4$