Molecules that show an appropriate number of bonds around each carbon atom are those in which each carbon forms four covalent bonds, fulfilling the octet rule and ensuring carbon's tetravalency. This means each carbon atom typically forms:
- Four single bonds, as in methane (CH4), where carbon bonds to four hydrogens.
- A combination of single and multiple bonds (double or triple) that add up to four bonds total. For example, carbon can form two single bonds and one double bond, or one single bond and one triple bond, as long as the total number of bonds is four.
- Bonds with other carbon atoms or heteroatoms (like oxygen, nitrogen, sulfur) while maintaining four bonds per carbon.
Examples include:
- Methane (CH4), where carbon has four single bonds.
- Ethane (C2H6), with carbons bonded to each other and hydrogens.
- Ethene (C2H4), where each carbon has a double bond plus two single bonds.
- Molecules with carbonyl groups (C=O), where the carbon forms a double bond with oxygen and two other bonds to satisfy four total bonds.
Carbons that do not have four bonds (e.g., three bonds with an unfilled valence shell) often carry a formal charge and are less stable or reactive intermediates (carbocations or carbanions)
. In summary, molecules showing an appropriate number of bonds around each carbon atom are those where each carbon is tetravalent, bonded to a total of four atoms or bonds (counting multiple bonds as multiple bonds), such as methane, ethane, ethene, and other typical organic molecules
