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Ionic Bonding

Ionic bonding is the chemical bonding formed by transfer of electrons from one atom to another, producing oppositely charged ions that attract each other strongly.

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Student-friendly explanation

In ionic bonding, a metal atom usually loses electron(s) to form a cation, and a non-metal atom gains electron(s) to form an anion. The strong electrostatic attraction between these ions forms an ionic compound. In solid state, ions are fixed in position, but in molten or aqueous state, ions become mobile and can conduct electricity.

How to write this in exams

  1. 1

    Start with the exact idea

    Ionic bonding is the chemical bonding formed by transfer of electrons from one atom to another, producing oppositely charged ions that attract each other strongly.

  2. 2

    Then show how to use it

    Identify metal and non-metal. Write electron loss and gain. Form cation and anion. Balance charges. State electrostatic attraction and relevant property.

  3. 3

    Add one concrete example

    In sodium chloride, sodium loses one electron to form Na+ and chlorine gains one electron to form Cl-. Oppositely charged ions attract to form an ionic lattice.

  4. 4

    Avoid this incomplete answer

    Saying a solid ionic compound conducts because electrons move freely is wrong because ionic compounds conduct through mobile ions, not free metallic electrons.

Definition

Ionic bonding is the chemical bonding formed by transfer of electrons from one atom to another, producing oppositely charged ions that attract each other strongly.

Example

In sodium chloride, sodium loses one electron to form Na+ and chlorine gains one electron to form Cl-. Oppositely charged ions attract to form an ionic lattice.

Rule to remember

Ionic bond: electron transfer followed by electrostatic attraction between cations and anions.

Memory hook

Fixed ions do not conduct; mobile ions conduct.

Examples and method

Worked example

Magnesium has two valence electrons and oxygen needs two electrons. Magnesium transfers two electrons to oxygen, forming Mg2+ and O2-. Their charges balance to give MgO.

Method to apply

Identify metal and non-metal. Write electron loss and gain. Form cation and anion. Balance charges. State electrostatic attraction and relevant property.

Diagram support

Use an electron-transfer dot diagram showing Na losing one electron to Cl, followed by Na+ and Cl- attraction in an ionic lattice.

How CBSE asks it

Asked through electron-transfer diagrams, conductivity of solid versus molten salt, high melting point, and formula formation from ion charges.

Avoid common mistakes

Common confusion

Students often say solid ionic compounds conduct electricity because they contain ions. They conduct only when ions are mobile, such as in molten or aqueous state.

Common wrong answer

Saying a solid ionic compound conducts because electrons move freely is wrong because ionic compounds conduct through mobile ions, not free metallic electrons.

Exam tip

For properties, write strong electrostatic attraction for high melting point and mobile ions for conductivity in molten or aqueous state.

Quick check

Why does solid sodium chloride not conduct electricity but molten sodium chloride does?

Solid sodium chloride has ions, but they are fixed in the lattice and cannot move. In molten sodium chloride, ions are mobile, so they carry charge and conduct electricity.

Study the ionic bonding diagram carefully

Use the labelled diagram to keep ionic bonding clear in short answers and revision.

What this diagram makes clear

This diagram keeps the labels and direction of ionic bonding in the right order.

Where this helps in exams

Use this for labelled diagram work and short exam answers on ionic bonding.

Revision cue

Revise ionic bonding through the labels before writing the answer.

Answer writing and exam use

1-mark answer

Ionic bonding is the chemical bonding formed by transfer of electrons from one atom to another, producing oppositely charged ions that attract each other strongly.

2-mark answer

Ionic bonding is the chemical bonding formed by transfer of electrons from one atom to another, producing oppositely charged ions that attract each other strongly. Ionic bond: electron transfer followed by electrostatic attraction between cations and anions. In sodium chloride, sodium loses one electron to form Na+ and chlorine gains one electron to form Cl-. Oppositely charged ions attract to form an ionic lattice.

3-mark answer

In ionic bonding, a metal atom usually loses electron(s) to form a cation, and a non-metal atom gains electron(s) to form an anion. The strong electrostatic attraction between these ions forms an ionic compound. In solid state, ions are fixed in position, but in molten or aqueous state, ions become mobile and can conduct electricity. Ionic bond: electron transfer followed by electrostatic attraction between cations and anions. Magnesium has two valence electrons and oxygen needs two electrons. Magnesium transfers two electrons to oxygen, forming Mg2+ and O2-. Their charges balance to give MgO. Asked through electron-transfer diagrams, conductivity of solid versus molten salt, high melting point, and formula formation from ion charges. Saying a solid ionic compound conducts because electrons move freely is wrong because ionic compounds conduct through mobile ions, not free metallic electrons.
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