Question

question 2
1 pts
a double bond consists of
one sigma and one pi bond.
one sigma bond containing four electrons.
two pi bonds
two sigma bonds.
question 3
1 pts
for the molecule ethylene ($c_2h_4$) draw the lewis dot structure. what are the number of $sigma$ and $pi$ bonds, respectively?
6; 0
1; 1
5; 1
3; 1

Explanation:

Question 2

To determine the composition of a double bond, we recall the principles of chemical bonding:

• A sigma ($\sigma$) bond is formed by head - on overlap of atomic orbitals, and a pi ($\pi$) bond is formed by lateral overlap.
• A single bond is only a $\sigma$ bond. A double bond consists of one $\sigma$ bond (from the head - on overlap) and one $\pi$ bond (from the lateral overlap).
• A sigma bond can have a maximum of 2 electrons (since it is a single bond - like overlap in terms of electron capacity for a single bond component), so a sigma bond containing four electrons is incorrect.
• A double bond does not have two $\pi$ bonds (a triple bond has two $\pi$ bonds and one $\sigma$ bond).
• A double bond also does not have two $\sigma$ bonds.

Step 1: Draw the Lewis structure of ethylene ($C_2H_4$)

Ethylene has a double bond between the two carbon atoms ($C = C$) and each carbon is bonded to two hydrogen atoms. The Lewis structure shows that the carbon - carbon double bond consists of one $\sigma$ bond and one $\pi$ bond, and each carbon - hydrogen bond is a $\sigma$ bond.

Step 2: Count the number of $\sigma$ and $\pi$ bonds

• Carbon - hydrogen bonds: Each carbon is bonded to 2 hydrogen atoms, so for 2 carbon atoms, there are $2\times2 = 4$ carbon - hydrogen $\sigma$ bonds.
• Carbon - carbon bond: The double bond between the two carbons has 1 $\sigma$ bond and 1 $\pi$ bond.
• Total $\sigma$ bonds: $4 + 1=5$
• Total $\pi$ bonds: 1 (from the carbon - carbon double bond)

Answer:

A. one sigma and one pi bond.

Question 3