Q14.35 P - Chemistry: Molecular Nature Of Matter And Change

Question

Draw Lewis structures for the following compounds, and predict which member of each pair will form hydrogen bonds:

(a) NF₃ or NH₃ (b) CH₃OCH₃ or CH₃CH₂OH

Step-by-Step Solution

Answer

(a) In the following given pair, only NH₃ will show hydrogen bonding:

(b) In the following given pair, only $C{H}_{3}C{H}_{2}OH$ (ethanol) will show hydrogen bonding:

Step 1: Lewis Structure

Lewis structure, also termed Lewis-dot structure, is a diagrammatical representation of a molecule, which shows bonding between the lone pairs of electrons and molecules or atoms that are located inside the molecule.

Lewis structure of hydronium ion

Step 2: Hydrogen bonding

Hydrogen bonding may be defined as the interaction of a hydrogen atom with an electronegative element, mainly fluorine, oxygen and nitrogen.

A hydrogen bond is weaker than a covalent or ionic bond, but is much stronger than van der Waal’s forces of interaction between the atoms. It is mainly of two types.

Intermolecular hydrogen bonding: This refers to the interaction between the hydrogen atoms of one molecule and an electronegative element of other molecules.

Intramolecular hydrogen bonding: This refers to the interaction between the hydrogen atoms of one molecule and the electronegative element of similar molecules.

 

Step 3: Predicting the molecule showing hydrogen bonding and drawing its Lewis structure

(a) In the following given pair (a), only NH₃ will show hydrogen bonding. This is a type of intramolecular hydrogen bonding.

(b) In the following given pair, only $C{H}_{3}C{H}_{2}OH$ (ethanol) will show hydrogen bonding. This is a type of intramolecular hydrogen bonding.