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 $C_2H_4$. Each carbon atom has 3 bonding regions and 0 lone pairs. There is a $C = C$ double - bond. Using the VSEPR (Valence - Shell Electron - Pair Repulsion) theory, when a central atom has 3 bonding regions and 0 lone pairs, the electron and molecular geometry around that atom is trigonal planar.

Step3: Analyze $C_2H_6$

$C_2H_6$ has only single bonds ($C - C$ and $C - H$), no double - bonds.

Step4: Analyze $CH_4$

$CH_4$ has a central carbon atom bonded to 4 hydrogen atoms with single bonds only, no double - bonds.

Answer:

1. $C_2H_4$