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Covalent Bond

A covalent bond is a chemical bond formed when two atoms share one or more pairs of electrons.

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Student-friendly explanation

Carbon and many non-metals prefer sharing electrons instead of losing or gaining them completely. By sharing, each atom gets a more stable outer shell. In carbon compounds, this idea is central because carbon usually forms strong covalent bonds with hydrogen, oxygen, nitrogen, and other carbon atoms. That is why organic chemistry is built mainly around covalent bonding.

How to write this in exams

  1. 1

    Start with the exact idea

    A covalent bond is a chemical bond formed when two atoms share one or more pairs of electrons.

  2. 2

    Then show how to use it

    1. Count the valence electrons of the atoms. 2. Check whether transfer is easy or difficult. 3. Show sharing of electron pairs. 4. Write the structure. 5. Verify that outer shells become stable.

  3. 3

    Add one concrete example

    In methane, CH4, carbon shares one electron each with four hydrogen atoms and forms four single covalent bonds.

  4. 4

    Avoid this incomplete answer

    A common wrong answer is that carbon donates four electrons. That is wrong because carbon does not easily lose four electrons in normal organic compounds.

Definition

A covalent bond is a chemical bond formed when two atoms share one or more pairs of electrons.

Example

In methane, CH4, carbon shares one electron each with four hydrogen atoms and forms four single covalent bonds.

Rule to remember

A covalent bond is a shared electron pair. Carbon is tetravalent, so it can form four covalent bonds. Single, double, and triple bonds mean one, two, or three shared pairs of electrons.

Memory hook

Share electrons, do not transfer them, when carbon makes stable molecules.

Examples and method

Worked example

In CH4, carbon has four valence electrons and each hydrogen has one. Carbon shares one electron with each hydrogen, so four shared pairs are formed. This gives carbon a stable octet and each hydrogen a stable duplet.

Method to apply

1. Count the valence electrons of the atoms. 2. Check whether transfer is easy or difficult. 3. Show sharing of electron pairs. 4. Write the structure. 5. Verify that outer shells become stable.

Diagram support

Draw overlapping shells or electron-dot structures to show shared electron pairs in methane, ethene, or other simple carbon compounds.

How CBSE asks it

Questions usually ask why carbon forms covalent compounds, how methane is bonded, or to draw an electron-dot structure of a simple molecule.

Avoid common mistakes

Common confusion

Students often think carbon gives away four electrons like a metal. Carbon does not usually form ions in simple carbon compounds.

Common wrong answer

A common wrong answer is that carbon donates four electrons. That is wrong because carbon does not easily lose four electrons in normal organic compounds.

Exam tip

While answering exam questions, always mention electron sharing and outer-shell stability, not electron transfer.

Quick check

Why does carbon usually form covalent bonds in its compounds?

Carbon has four valence electrons, so losing or gaining four electrons is difficult. It becomes stable by sharing electrons with other atoms, which is why it usually forms covalent bonds.

Answer writing and exam use

1-mark answer

A covalent bond is a chemical bond formed when two atoms share one or more pairs of electrons.

2-mark answer

A covalent bond is a chemical bond formed when two atoms share one or more pairs of electrons. A covalent bond is a shared electron pair. Carbon is tetravalent, so it can form four covalent bonds. Single, double, and triple bonds mean one, two, or three shared pairs of electrons. In methane, CH4, carbon shares one electron each with four hydrogen atoms and forms four single covalent bonds.

3-mark answer

Carbon and many non-metals prefer sharing electrons instead of losing or gaining them completely. By sharing, each atom gets a more stable outer shell. In carbon compounds, this idea is central because carbon usually forms strong covalent bonds with hydrogen, oxygen, nitrogen, and other carbon atoms. That is why organic chemistry is built mainly around covalent bonding. A covalent bond is a shared electron pair. Carbon is tetravalent, so it can form four covalent bonds. Single, double, and triple bonds mean one, two, or three shared pairs of electrons. In CH4, carbon has four valence electrons and each hydrogen has one. Carbon shares one electron with each hydrogen, so four shared pairs are formed. This gives carbon a stable octet and each hydrogen a stable duplet. Questions usually ask why carbon forms covalent compounds, how methane is bonded, or to draw an electron-dot structure of a simple molecule. A common wrong answer is that carbon donates four electrons. That is wrong because carbon does not easily lose four electrons in normal organic compounds.
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