Question

name:
block:
date:
unit: energy in chemical reactions
lesson: covalent bonding
standard:
objective: students will understand the concept of covalent bonding (the sharing of electrons).
a molecule of carbon dioxide (co₂) contains one carbon atom and two oxygen atoms. carbon has 4 valence electrons, and oxygen has 6 valence electrons.
part a:
explain why carbon forms two double covalent bonds in a co₂ molecule instead of single bonds.

Explanation:

Carbon has 4 valence electrons. It needs 4 more electrons to achieve a stable octet (like noble gases). Each oxygen has 6 valence electrons and needs 2 more. If carbon formed single bonds with two oxygens (each single bond shares 1 pair of electrons), carbon would only gain 2 electrons (total 6, not stable). By forming double bonds (each double bond shares 2 pairs of electrons), carbon gains 4 electrons (total 8, stable) and each oxygen gains 2 electrons (total 8, stable).

Answer:

Carbon forms two double covalent bonds in \(CO_2\) to achieve a stable electron configuration (octet rule). With double bonds, carbon (4 valence electrons) gains 4 electrons (total 8) and each oxygen (6 valence electrons) gains 2 electrons (total 8). Single bonds would not satisfy the octet for carbon (only 6 electrons if two single bonds).