Question

2. When carbohydrates are oxidized, the C-H bonds of the carbohydrate become C=O bonds of carbon dioxide. Oxidation is defined as a loss of electrons, but carbon does not become positively charged in the process. Why then is this considered oxidation?
A) The shared electrons in C-O bonds spend less time close to the carbon nucleus than the shared electrons in C-H bonds.
B) Electrons in the C=O bonds are higher energy than the electrons in the C-H bonds.
C) C=O bonds in CO2 are double bonds, and C-H bonds are single bonds.
D) The phosphate groups of ATP are ionized, and carbons donate those electrons.

Answer 1

Answer:

A) The shared electrons in C-O bonds spend less time close to the carbon nucleus than the shared electrons in C-H bonds.

Explanation:

The electronegativity from H is 2.2, from C is 2.55 and from O is 3.44. This property is the measure of the attractive force between an atom and a pair of electrons.

So, the difference of electronegativity of H and C is smaller than the difference between O and C. Because oxygen is more electronegative, the electrons stay close to it in the bond C=O. So carbon has a partial positive charge in that bond. For the bond C-H, the shared electrons stay closes to carbon.