What is Covalent Bonding?
Covalent bonding is when two atoms share one or more pairs of electrons to achieve stable, filled outer shells. It's the primary bonding in molecules and is very common in organic compounds, water, and gases.
In covalent bonding, atoms share electrons rather than transfer them. A single bond shares 1 electron pair (1 line), double bonds share 2 pairs (2 lines), and triple bonds share 3 pairs (3 lines).
- •Electron transfer
- •Cation + anion
- •Electrostatic attraction
- •e.g., NaCl, MgO
- •Electron sharing
- •Two atoms
- •Shared electron pair
- •e.g., H₂, H₂O, O₂
Step-by-step worked examples
Hydrogen (H) forms H₂ by sharing electrons. How many electron pairs are shared?
Hydrogen: 1 proton, 1 electron (needs 2 electrons for stability) Two H atoms approach each other Each contributes 1 electron to a shared pair Shared pair: 1 electron pair (single bond H—H)
In water (H₂O), oxygen bonds with two hydrogens. How many single bonds?
Oxygen: 8 protons, 6 valence electrons (needs 2 more) Hydrogen: 1 proton, 1 valence electron (needs 1 more each) O shares 1 electron pair with each H Total: 2 single bonds (H—O—H)
In carbon dioxide (CO₂), carbon shares electrons with two oxygens. What type of bonds?
Carbon: 6 protons, 4 valence electrons (needs 4 more) Oxygen: 8 protons, 6 valence electrons (needs 2 more each) Each C=O shares 2 electron pairs Total: 2 double bonds (O=C=O)
Flashcards
Quick quiz
Q1.In covalent bonding, electrons are ___.
Q2.How many electron pairs does a single bond contain?
Q3.In O=C=O (carbon dioxide), how many double bonds are there?
Q4.Which molecule has only single bonds: H₂O, O₂, or N₂?
The full card deck, worked steps and AI-tutor support for “What is Covalent Bonding?” are in Notek — study by hand before your exam.
Common mistakes
Covalent bonding is the same as ionic bonding. — Correct: Covalent bonding shares electrons; ionic bonding transfers electrons.
Only metals can form covalent bonds. — Correct: Non-metals typically form covalent bonds with each other.
A double bond is always stronger than a single bond. — Correct: Double bonds are stronger (2 pairs vs 1), but a triple bond is even stronger.
Covalent compounds are always molecular. — Correct: Most are molecular, but some (like diamonds) are network covalent solids.
FAQ
Why do atoms form covalent bonds?
Atoms share electrons to achieve stable, filled outer electron shells (octet rule for most non-metals).
What is the difference between a single, double, and triple bond?
Single bond = 1 shared pair, double bond = 2 shared pairs, triple bond = 3 shared pairs. Triple bonds are strongest.
Can an atom form more than one covalent bond?
Yes — most atoms form multiple bonds (e.g., carbon typically forms 4 covalent bonds).
What are examples of covalent molecules?
H₂, H₂O, CO₂, NH₃, O₂, N₂, and most organic molecules.