Predict the correct order among the following:
- lone pair-lone pair > bond pair-bond pair > lone pair - bond pair
- bond pair - bond pair > lone pair - bond pair > lone pair - lone pair
- lone pair - bond pair > bond pair - bond pair > lone pair - lone pair
- lone pair - lone pair > lone pair - bond pair > bond pair - bond pair
The Correct Option is D
Solution and Explanation
VSEPR Theory: Lone Pair Repulsion
According to the Valence Shell Electron Pair Repulsion Theory (VSEPR), the repulsion between electron pairs in the valence shell of an atom determines the shape of a molecule. In this theory, it is important to understand that lone pairs of electrons experience greater repulsion than bonding pairs.
Lone Pair-Lone Pair Repulsion
Lone pairs are electron pairs that are not involved in bonding. These lone pairs are localized on one atom and are held more tightly by the nucleus of that atom, which makes them occupy more space. As a result, lone pairs repel each other more strongly than bonding pairs.
The order of repulsion strength according to VSEPR theory is:
lone pair-lone pair>lone pair-bond pair>bond pair-bond pair
Explanation:
- Lone Pair-Lone Pair Repulsion: This is the strongest repulsion because both lone pairs are localized on the same atom and are held tightly by the nucleus, leading to significant spatial demand.
- Lone Pair-Bond Pair Repulsion: The repulsion between a lone pair and a bonding pair is less than that between two lone pairs, as the bonding pair is shared between atoms.
- Bond Pair-Bond Pair Repulsion: This is the weakest repulsion because bonding pairs are spread out over the bond and are held by two nuclei, reducing their spatial repulsion.
In summary, lone pairs occupy more space due to their stronger attraction to the nucleus, which leads to greater repulsion compared to bonding pairs.
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Concepts Used:
Chemical Bonding and Molecular Structure
Such a group of atoms is called a molecule. Obviously, there must be some force that holds these constituent atoms together in the molecules. The attractive force which holds various constituents (atoms, ions, etc.) together in different chemical species is called a chemical bond.
Types of Chemical Bonds:
There are 4 types of chemical bonds which are formed by atoms or molecules to yield compounds.
- Ionic Bonds - Ionic bonding is a type of chemical bonding which involves a transfer of electrons from one atom or molecule to another.
- Covalent Bonds - Compounds that contain carbon commonly exhibit this type of chemical bonding.
- Hydrogen Bonds - It is a type of polar covalent bonding between oxygen and hydrogen wherein the hydrogen develops a partial positive charge
- Polar Bonds - In Polar Covalent chemical bonding, electrons are shared unequally since the more electronegative atom pulls the electron pair closer to itself and away from the less electronegative atom.
Factors Affecting Bond Enthalpy in Chemical Bonding:
- Size of the Atom
- Multiplicity of Bonds
- Number of Lone Pair of Electrons Present
- Bond Angle