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Organic Chemistry Questions and Short Answers

What is the role of atomic size in London Dispersion? Explain with an example.

London dispersion forces are the weak intermolecular forces that occur when the molecules are in close proximity to each other. The strength of these forces is determined by the atomic size of the element.

In smaller atoms, the atomic radius is smaller, which means that the positively charged nucleus holds the outermost valence electrons more firmly, leaving less room for their dispersion or polarization.

Which molecules show London Dispersion Force?

All atoms and molecules show London Dispersion Force, a primary way atoms and molecules interact. Most of the time, molecules have additional stronger forces than the London Dispersion Force, which is the weakest. Therefore, London Dispersion forces are exclusively seen in the nonpolar molecules since they don't have other competing functional groups leading to other interfering intermolecular interactions.

Why are Debye forces called the induction effect?

Debye intermolecular forces of attraction occur between polar and nonpolar atoms or molecules. When closely placed with a polar molecule (electronegativity difference between 0.5-1.7), the electron cloud of the nonpolar atom (or molecule) is influenced and distorted, leading to the formation of temporary dipoles. As the polarity is induced (forced) in the otherwise nonpolar atom, the Debye forces are said to show an Induction effect.

How to determine the hybridization of C in CH4?

If only valence shells participate in bonding reactions, then Carbon should only form two bonds using its two unpaired electrons. However, Carbon forms four bonds, as seen in CH4, CH3X, H2C=O, and O=C=O molecules. This discrepancy between the number of valence electrons of an atom and the number of bonds it forms (valency) is explained by the hybridization concept, an extension of the Valence Bond (VB) Theory.