Chapter 4: Problem 32
Octet rule is not valid for the molecule (1) \(\mathrm{CO}_{2}\) (2) \(\mathrm{H}_{2} \mathrm{O}\) (3) \(\mathrm{O}_{2}\) (4) CO
Short Answer
Step by step solution
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Valence Electrons
These electrons determine how atoms interact and bond with each other.
In most cases, atoms bond to achieve a stable electron configuration similar to noble gases, which typically means having eight valence electrons—known as the octet rule.
For example, oxygen in the molecule \(\text{H}_{2}\text{O}\) has six valence electrons and needs two more to complete its octet. By forming two single bonds with hydrogen, oxygen achieves the octet configuration.
Similarly, carbon in \(\text{CO}_{2}\) shares four valence electrons with two oxygen atoms through double bonds, allowing all atoms to fulfill the octet rule.
Chemical Bonding
There are three primary types of chemical bonds: ionic, covalent, and metallic bonds.
In covalent bonding, atoms share valence electrons. This sharing can be equal (non-polar) or unequal (polar), depending on the atoms involved.
For instance, in the molecule \(\text{O}_{2}\), each oxygen atom shares two electrons with another oxygen atom, creating a double bond.
In covalent bonds, atoms can share one pair (single bond), two pairs (double bond), or three pairs (triple bond) of electrons, depending on the molecule's requirements.
Molecular Structure
How atoms are bonded in a molecule determines its geometry and shape.
For example, in the \(\text{CO}_{2}\) molecule, the carbon atom is at the center with double bonds connecting to each oxygen atom, forming a linear structure.
Molecular structure also determines whether a molecule adheres to the octet rule. In \(\text{H}_{2}\text{O}\), the bent structure arises because oxygen not only forms two single bonds with hydrogen but also holds two lone pairs of electrons.
The placement and sharing of electrons in these structures are crucial in dictating how molecules interact with each other.
Triple Bond
This bond significantly impacts the molecular structure and properties of the molecule.
For instance, in the molecule carbon monoxide (CO), a triple bond forms between the carbon and oxygen atoms. This causes the molecule to be linear and contributes to its unique chemical properties.
The triple bond in CO means each carbon and oxygen atom shares three electrons, but carbon ends up with only six valence electrons, violating the octet rule.
Triple bonds are shorter and stronger than single and double bonds, owing to the greater number of shared electrons between the bonded atoms.