Incomplete octets w/ lone pair

[susan__t]

I was just wondering how you might use Lewis theory to predict the reaction of molecules with an incomplete octet with a molecule that contains a lone pair? The idea is very abstract to me, I'd appreciate any ideas.

 

[Borek]

Check if after reaction you will not get full octets (with some electrons shared).

 

[Blueshift5]

Lewis theory, also known as the octet rule, states that atoms tend to gain, lose, or share electrons in order to achieve a stable octet (8 valence electrons) in their outermost energy level. However, there are exceptions to this rule, particularly with elements in the third period or higher on the periodic table.

In the case of molecules with incomplete octets, such as boron trifluoride (BF3) or beryllium chloride (BeCl2), these molecules have an odd number of valence electrons and cannot achieve a stable octet through bonding alone. This is where the concept of a lone pair comes into play. A lone pair is a pair of valence electrons that are not involved in bonding and are located on an atom's outermost energy level.

When a molecule with an incomplete octet comes into contact with a molecule containing a lone pair, such as ammonia (NH3) or water (H2O), the lone pair can form a bond with the incomplete octet molecule. This results in the formation of a coordinate covalent bond, where the shared pair of electrons comes from only one of the atoms involved in the bond.

For example, in the reaction between boron trifluoride and ammonia, the lone pair on the nitrogen atom can bond with the incomplete octet on the boron atom, resulting in the formation of a stable molecule, boron trifluoride ammonia complex (BF3-NH3). This reaction can be predicted using Lewis theory by looking at the number of valence electrons on each atom and determining if they can achieve a stable octet through bonding.

In summary, Lewis theory can be used to predict the reaction of molecules with incomplete octets with molecules containing lone pairs by considering the concept of coordinate covalent bonds. This understanding is important in chemistry as it helps explain the behavior and stability of molecules that do not follow the octet rule.