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Properties of Ionic vs Covalent Compounds

Ionic and covalent compounds differ in properties because ionic compounds have ions in a lattice, while covalent compounds usually have molecules formed by shared electrons.

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Student-friendly explanation

Ionic compounds generally have high melting points due to strong electrostatic attraction between ions. They conduct electricity in molten or aqueous state because ions are mobile. Many covalent compounds have lower melting and boiling points and do not conduct electricity because they have neutral molecules without mobile ions.

How to write this in exams

  1. 1

    Start with the exact idea

    Ionic and covalent compounds differ in properties because ionic compounds have ions in a lattice, while covalent compounds usually have molecules formed by shared electrons.

  2. 2

    Then show how to use it

    Read the observation. Check melting point, conductivity state, and solubility clue. Link each property to structure. Conclude ionic or covalent with reason.

  3. 3

    Add one concrete example

    Sodium chloride has a high melting point and conducts in solution, while sugar is covalent and does not conduct electricity in solution in the same way.

  4. 4

    Avoid this incomplete answer

    Saying a dry ionic solid conducts because it has ions is incomplete and usually wrong, because the ions are fixed and cannot carry charge.

Definition

Ionic and covalent compounds differ in properties because ionic compounds have ions in a lattice, while covalent compounds usually have molecules formed by shared electrons.

Example

Sodium chloride has a high melting point and conducts in solution, while sugar is covalent and does not conduct electricity in solution in the same way.

Rule to remember

Property rule: structure controls property; ionic lattice gives strong attraction and mobile-ion conduction when molten or aqueous, while covalent molecules usually lack mobile ions.

Memory hook

Structure first, property next.

Examples and method

Worked example

If a solid has high melting point and conducts only when dissolved in water, it is likely ionic because fixed ions become mobile in solution.

Method to apply

Read the observation. Check melting point, conductivity state, and solubility clue. Link each property to structure. Conclude ionic or covalent with reason.

Diagram support

A comparison table can show structure, melting point, conductivity, and solubility for ionic and covalent compounds.

How CBSE asks it

Asked as property comparison, identification of compound type from observations, or reason-based questions on conductivity and melting point.

Avoid common mistakes

Common confusion

Students often memorise one property and apply it to all compounds. The correct property depends on structure and the presence of mobile charged particles.

Common wrong answer

Saying a dry ionic solid conducts because it has ions is incomplete and usually wrong, because the ions are fixed and cannot carry charge.

Exam tip

For comparison answers, write property plus reason: high melting point due to strong ion attraction, conductivity due to mobile ions, and poor conductivity of covalent compounds due to neutral molecules.

Quick check

Why do molten ionic compounds conduct electricity but most covalent liquids do not?

Molten ionic compounds contain mobile ions that can carry charge. Most covalent liquids contain neutral molecules, so they do not have mobile ions to conduct electricity.

Answer writing and exam use

1-mark answer

Ionic and covalent compounds differ in properties because ionic compounds have ions in a lattice, while covalent compounds usually have molecules formed by shared electrons.

2-mark answer

Ionic and covalent compounds differ in properties because ionic compounds have ions in a lattice, while covalent compounds usually have molecules formed by shared electrons. Property rule: structure controls property; ionic lattice gives strong attraction and mobile-ion conduction when molten or aqueous, while covalent molecules usually lack mobile ions. Sodium chloride has a high melting point and conducts in solution, while sugar is covalent and does not conduct electricity in solution in the same way.

3-mark answer

Ionic compounds generally have high melting points due to strong electrostatic attraction between ions. They conduct electricity in molten or aqueous state because ions are mobile. Many covalent compounds have lower melting and boiling points and do not conduct electricity because they have neutral molecules without mobile ions. Property rule: structure controls property; ionic lattice gives strong attraction and mobile-ion conduction when molten or aqueous, while covalent molecules usually lack mobile ions. If a solid has high melting point and conducts only when dissolved in water, it is likely ionic because fixed ions become mobile in solution. Asked as property comparison, identification of compound type from observations, or reason-based questions on conductivity and melting point. Saying a dry ionic solid conducts because it has ions is incomplete and usually wrong, because the ions are fixed and cannot carry charge.
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