Question

Define electronegativity. Discuss the favorable conditions for the formation of non-polar covalent bonds, polar covalent bonds, and ionic bonds, based on the electronegativity difference between bonded atoms.

Answer 1

Step1 : Electronegativity:

• The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is known as electronegativity.
• The element with a higher value of electronegativity more readily attracts an electron.

Step 2: Favorable conditions for the formation of non-polar covalent bonds, polar covalent bonds, and ionic bonds based on the electronegativity

Bond Formation and its types:

• A chemical bond is formed between two or more atoms, molecules, or ions either by sharing or transferring electrons.
• There are three major bonds namely- The ionic bond, the Covalent, and the Metallic bond.
• Again covalent bond is classified into two types: Non-polar covalent bond and Polar covalent bond.

Favorable conditions for the Bond formation and electronegativity:

Covalent Bond:

• Covalent bonds occur between the atoms by sharing electrons.
• For example, in an $\mathrm{HCl}$ molecule- One Hydrogen atom with one valence electron is shared with one Chlorine atom with seven valence electrons.
• Polar covalent bonds occur when two or more atoms with different electronegativities share electrons in a covalent bond.
• A few examples of polar covalent bonds are water$\left({\mathrm{H}}_2\mathrm{O}\right)$ and ammonia$\left({\mathrm{NH}}_3\right)$.
• Non-Polar covalent bonds occur when two or more atoms with the same electronegativities share electrons in a covalent bond.
• A few examples of non-polar covalent bonds are Oxygen molecules($O_2$), Hydrogen molecules($H_2$), and Nitrogen molecules($N_2$).

Ionic Bond:

• Ionic bonds occur between the atoms by transferring one or more electrons from one atom to another atom.
• Ionic bonds occur when the electronegativity of any one atom must be high.
• An example of an ionic bond is Sodium chloride($NaCl$).

Electronegativity difference:

• The electronegativity difference value is between 0 to 0.3 for non-polar covalent bonds.
• For example Hydrogen molecules, Hydrogen has an electronegativity of 2.1 and its difference becomes zero in the hydrogen molecules.
• The electronegativity difference value is between 0.4 to 1.8 for a polar covalent bond.
• For example Water, Hydrogen$\left(\mathrm{H}\right)$ has an electronegativity of 2.1, Oxygen$\left(\mathrm{O}\right)$ has a 3.5 and the difference is 1.4
• The electronegativity difference value is greater than 1.8 for an ionic bond.
• Example Sodium chloride$\left(\mathrm{NaCl}\right)$, Sodium$\left(\mathrm{Na}\right)$ has an electronegativity of 0.93, Chlorine has 3.16 and the difference is 2.23