Answer:
Explanation:
A molecule with one bonding pair (BP) and one lone pair (LP), or one bonding pair and two lone pairs, does not typically exist due to the requirements for forming a stable molecule. Here's why:
1. **Molecule with 1 Bonding Pair and 1 Lone Pair:**
- For a molecule to exist with a single bonding pair and a single lone pair, there would need to be at least two atoms. A diatomic molecule with only one bonding pair already forms a stable structure (like HCl, HF, etc.). The lone pair would imply the presence of another atom that is not involved in bonding, which would create a radical or ion rather than a stable molecule.
2. **Molecule with 1 Bonding Pair and 2 Lone Pairs:**
- Similarly, a molecule with one bonding pair and two lone pairs would imply a very specific arrangement of electrons. The simplest case would be a triatomic species with one central atom having two lone pairs and forming a single bond with another atom. For example, a neutral molecule like this is not feasible because a single bond with two lone pairs would leave an incomplete octet for many elements, especially those from the second period of the periodic table.
### More Detail:
- **One Bonding Pair and One Lone Pair:**
- A typical molecule like this is not feasible because, with only one bonding pair, the second atom involved in bonding would not leave an extra lone pair without leading to either an incomplete or expanded octet.
- **One Bonding Pair and Two Lone Pairs:**
- If we consider a hypothetical molecule like X with one bonding pair and two lone pairs (e.g., X-BY), X must be able to accommodate five electrons in its valence shell. However, most elements that can form stable bonds (like second-period elements) do not fit this description as they typically follow the octet rule. A neutral stable molecule with this configuration doesn't exist for these reasons. Examples like water (H₂O) have two bonding pairs and two lone pairs instead.
### Conclusion:
Molecules are usually structured to follow the octet rule (for second-period elements) or to achieve a stable electron configuration. The hypothetical configurations you mentioned don't form stable molecules under normal circumstances due to the limitations of electron pairing and the requirement for stable bonding structures.
