Ionic Compounds: Formation, Properties, Examples & Reasoning Questions for Matric Chemistry

Have you ever wondered how salts are formed? Why are some compounds soluble in water while others are not? This is due to the special type of chemical bond called an Ionic Bond. In this blog, we'll explore how ionic bonds are formed, their properties, and daily life examples.

What is an ionic bond?

A type of chemical bond that is formed due to the complete transfer of electrons between two atoms. One atom donates an electron, and the other one accepts an electron.

These oppositely charged ions strongly attract each other due to the Electrostatic force of attraction.

Example:

Let's take an example of table salt (NaCl).

Sodium (Na) is a metal. It belongs to Group I-A and has one electron in its outermost shell. It wants to lose it to become stable, whereas Chlorine (Cl) is a non-metal. It belongs to Group VII-A and has seven electrons in its outermost shell. It wants to gain one electron to complete its octet.

Therefore, sodium gives one electron to chlorine and becomes a sodium ion (Na⁺), whereas Chlorine becomes a chlorine ion (Cl⁻). 

These oppositely charged ions attract each other by electrostatic force of attraction and form sodium chloride, the table salt we use daily.

Properties of Ionic Compounds

1. Ionic compounds form crystal solids with a regular pattern.
2. They are easily soluble in water.
3. They conduct electricity when soluble in water as their freely moving ions carry an electric current through the solution.
4. They have high melting and boiling points.

Everyday Examples of Ionic Compounds

• NaCl is used in food.
• MgCl₂ is used in medicine
• CaCl₂ is used in preserving foods
• MgO is used in medicine and industry.

Reasoning Questions

Explain why ionic compound is considered to have a strong bond.

As ionic compounds have positive (cations) and negative (anions) ions, they are held together by a strong force of attraction called the electrostatic force of attraction. A large amount of heat is required to break these bonds.

Why do ionic compounds conduct electricity in solution but not in the solid state?

The solution of ionic compounds has freely moving ions so they can conduct an electric current in a solution.

Why does sodium form a positive ion after losing an electron?

The atomic number of sodium is 11, so they have 11 electrons and 11 protons. The outermost shell of sodium contains only 1 electron. To gain stability, sodium loses its outer shell electron and forms a positive ion (cation). Now the sodium has 1 more proton than electrons, so it becomes a positively charged ion (Na⁺).

Why do elements form ionic bonds instead of sharing electrons like a covalent bond?

An ionic bond is formed when the electronegativity difference between two atoms is 1.7 or greater. Usually, metals have low electronegativity while non-metals have high electronegativity values. Because of this significant difference in electronegativity value, it is energetically more favourable to transfer electrons than to share.

Why do ionic compounds have high melting and boiling points?

Ionic compounds have high melting and boiling points because of the presence of electrostatic force between oppositely charged ions, which is very strong. A large amount of heat energy is required to break these strong bonds. Therefore, ionic compounds stay solid at room temperature and need a high temperature to break apart.

Conclusion

Ionic compounds play an important role in daily life, from the salt in the kitchen to medicine or industry. They are formed by transferring electrons between two atoms. They have unique features, including high melting and boiling points, conduct electricity in solution, etc. Understanding Ionic compounds helps us to make sense of the structure and behavior of many substances around us.