Covalent bond
- CBSE · NCERT Class 10, Ch 4 Carbon and its Compounds
A covalent bond is a bond formed when two atoms share a pair of electrons, so that each atom gets a full outer shell.
Carbon has 4 electrons in its outer shell. To fill it, it would have to gain 4 or lose 4, and both take too much energy. So carbon shares electrons instead. That sharing is a covalent bond.
- One shared pair: a single bond, as in H–H.
- Two shared pairs: a double bond, as in O=O.
- Three shared pairs: a triple bond, as in N≡N.
Covalent compounds usually have low melting and boiling points. They are poor conductors of electricity, because they form no ions. Compare an ionic compound.
A small example
Methane is CH₄. Carbon shares one of its 4 electrons with each of 4 hydrogen atoms. Each hydrogen shares its 1 electron back. That makes 4 shared pairs, so 4 single bonds. Carbon now has 8 electrons around it, and each hydrogen has 2. All shells are full.
Where marks go
Question 26 of CBSE's 2026-27 Science sample paper describes compound X, C₂H₆O, used in medicines and blended with petrol. Its first part asks for the electron dot structure of X. The 2026-27 Science marking scheme gives 1 mark for the drawing.
X is ethanol. The drawing shows every shared pair between its atoms. Check that each carbon has 8 electrons around it and each hydrogen has 2. See where the marks go in CBSE Science.
Sources
Facts last checked against these sources on 30 September 2026.
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