In an electron dot diagram of propane (C3H8), how many double bonds are present?
one
two
three
none
The Correct Answer and explanation is :
In an electron dot diagram (also known as a Lewis dot structure) of propane (C₃H₈), there are none present. Propane is an alkane, which means it consists of single bonds between carbon atoms and is fully saturated with hydrogen atoms.
Explanation
- Structure of Propane: Propane has three carbon (C) atoms and eight hydrogen (H) atoms. The molecular formula indicates that propane is a straight-chain hydrocarbon with the structure: H₃C-CH₂-CH₃.
- Bonding in Propane: Each carbon atom in propane forms four bonds to achieve a full octet, which is a stable electron configuration. In propane, the two terminal carbon atoms (CH₃ groups) each bond with three hydrogen atoms and one bond to the middle carbon atom (CH₂). The middle carbon atom bonds to the two terminal carbons, completing its four bonds with two hydrogen atoms and two carbon-carbon single bonds.
- Electron Dot Diagram: In the Lewis dot structure of propane, the carbon atoms are represented with their valence electrons and lines indicating bonds. For each bond between carbon and hydrogen (C-H) or between carbon and carbon (C-C), a single line (representing a single bond) is drawn. This means that each bond consists of two shared electrons. When constructing the electron dot diagram for propane, you will see that all bonds are single bonds, with no double or triple bonds present.
- Saturation: Since propane is an alkane (a saturated hydrocarbon), it does not contain double or triple bonds, which are characteristic of unsaturated hydrocarbons like alkenes and alkynes. The presence of double bonds would imply that there are fewer hydrogen atoms than what would be found in a saturated hydrocarbon.
In conclusion, the electron dot diagram of propane (C₃H₈) reveals that there are no double bonds; all the bonds are single, fulfilling the requirements of a saturated compound.