9.3.8 Ionic Compounds vs Covalent Compounds
This is the eighth lecture from Chapter 3: “Chemical Bonding” in the new Class 9 Chemistry book (Punjab Board – PCTB). It covers the differences between ionic compounds and covalent compounds. The lecture also includes a multiple-choice quiz, short question and long question notes.
MCQs Based Quiz
Short Questions
Why do ionic compounds have high melting and boiling points?
Ionic compounds have high melting and boiling points because their ions are firmly held by strong electrostatic attractions. For example, melting point of NaCl is 801°C.
What is the difference between the solubility of ionic and covalent compounds?
Ionic compounds are generally soluble in polar solvents such as water.
Polar covalent compounds also dissolve in water, while non-polar covalent compounds are soluble in non-polar solvents like ether, benzene, or acetone.
Write three properties of ionic compounds.
- They are made of at least one metal and one non-metal.
- Electrostatic force of attraction is present between cations and anions.
- They are generally soluble in polar solvents like water.
Write three properties of covalent compounds.
- Covalent compounds mostly exist as individual neutral units.
- They are made of two or more non-metals.
- They are usually bad conductors of electricity.
Descriptive Question
Q1. Give a detailed comparison between ionic compounds and covalent compounds?
Ionic Compounds
Covalent Compounds
In ionic compounds, oppositely charged ions are perfectly arranged in a crystalline structure. As a whole, the compound is neutral.
Covalent compounds mostly exist as individual neutral units.
They are made of at least one metal and one non-metal.
They are made of two or more non-metals.
Electrostatic forces of attraction exist between the cations and anions.
Electrostatic force of attraction exists between nuclei and shared electrons.
They usually have very high melting and boiling points due to strong electrostatic attractions between ions, which are difficult to break. For example, the melting point of NaCl is 801°C.
Their lower molecular mass compounds are gases and have low melting and boiling points. High molecular mass compounds are solids, but they also have lower melting and boiling points than ionic compounds.
Most ionic compounds are solids at room temperature. Example: sodium chloride (NaCl).
They exist in all states, i.e., solid, liquid and gas.
They are generally soluble in polar solvents, such as water.
Polar compounds are soluble in polar solvents, while non-polar compounds are soluble in non-polar solvents.
They are good conductors of electricity in molten or aqueous solution form, because in these states, the ions are free to move.
They are usually bad conductors of electricity.
Examples: NaCl, KCl, CaCl2
Examples: H2O, CO2 and HCl