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Chapter 4 — chapter 4
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📘Easy summary
A mole is the amount of substance that contains as many particles (atoms, molecules, ions or formula units) as there are atoms in exactly 12 g of carbon-12, i.e. Avogadro's number Nₐ = 6.022 × 10²³. Thus the mole is derived from Avogadro's number: 1 mol of any substance contains 6.022 × 10²³ particles. 1 mol of O₃ contains Nₐ molecules but 3Nₐ oxygen atoms. Equal moles of different elements (39 g K and 56 g Fe, each 1 mol) contain equal numbers of atoms.
⭐Key points
- 1 mol = 6.022 × 10²³ particles.
- Particles = moles × Nₐ.
- Atoms = molecules × atomicity.
🔬Diagram
🌿Real-life example
14.0 g N₂ = 0.5 mol = 3.01 × 10²³ molecules = 6.02 × 10²³ N atoms.
💡Exam tip
- Distinguish molecules from atoms.
✅Quick check
1. Atoms in 1 mol O₃:
2. Particles in 12 g C-12:
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