CHM014 · Bonding & Molecular Shape · Classes 7–12
Covalent Bonding
Objective: To build covalent molecules and count shared electron pairs.
🧰 Virtual materials and apparatus
- Virtual ball-and-stick model kit
- Atoms coloured by element (H white, C black, N blue, O red)
📐 Formulas and SI units
bond order = shared pairs between two atoms
💡 Theory
Non-metal atoms bond by sharing pairs of electrons. One shared pair is a single bond, two a double bond and three a triple bond. Each atom then has a full outer shell. Lone pairs are outer electron pairs not used in bonding.
🪜 Guided virtual procedure
- Choose N₂ and count the sticks between the atoms.
- Read the bond list and shared pairs.
- Try O₂ (double) and H₂ (single).
- Build H₂O, NH₃ and CH₄ and count bonds to the central atom.
- Compare lone pairs.
📋 Observations Simulated values
✅ Result and conclusion
N₂ has a triple bond (3 shared pairs), which makes it very unreactive.
🔬 Real lab vs simulation
Sticks are a model: shared electrons are spread in clouds, and bond lengths differ (N≡N 110 pm, O=O 121 pm, H–H 74 pm).
⚠️ Safety
Model kits only. Real laboratory chemicals are handled only by teachers in a school laboratory.
❓ Quick check
1. How many shared pairs in O₂?
2. CH₄ has how many C–H bonds?
3. Covalent bonds form between…
🏋️ Practice
EasyBonds in CO₂?
Answer: Two C=O double bonds
MediumLone pairs on oxygen in H₂O?
Answer: 2
ChallengeType of bond in H₂?
Answer: Single covalent