Key Summary & High-Yield Concept Takeaways
Curated by senior faculty at Hodu Academy for fast revision, formula derivations, and standard board & competitive exam marking schemes.
- ✓IGCSE Chemistry Syllabus Chapters
- ✓Chapter-wise Formulas, Facts & Worked Examples
- ✓Organic Chemistry Reactions & Shortcuts
- ✓Summary Tables & Units
IGCSE Chemistry Formulas & Key Facts – Cambridge 0620/0971 [All Chapters]
IGCSE Chemistry (0620/0971) covers the foundation of chemistry—atomic structure, bonding, periodicity, reactions, calculations, acids-bases, organic chemistry, and more. Hodu Academy presents an organized chapter-wise collection of all-important formulas, equations, definitions, worked examples, and exam tips—all mapped to the Cambridge syllabus for your best exam performance.
Use these formula sheets, summary tables, worked examples, and revision notes for rapid recall before your IGCSE exams or checkpoints. Suitable for Cambridge IGCSE, O Level, and similar international boards.
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Get in-depth explanations and walkthroughs for every chapter on our YouTube Chemistry Playlist. Perfect for visual learning and step-by-step guidance!
Table of Contents
IGCSE Chemistry Syllabus Chapters
| Syllabus Section | Topics |
|---|---|
| 1. The Particulate Nature of Matter | States of matter, diffusion, changes of state |
| 2. Experimental Techniques | Purification, separation, measurement |
| 3. Atoms, Elements & Compounds | Atomic structure, isotopes, bonding |
| 4. Stoichiometry | Mole, equations, calculations |
| 5. Electricity & Chemistry | Electrolysis, conductors, half-equations |
| 6. Chemical Energetics | Exo/endothermic, enthalpy, calorimetry |
| 7. Chemical Reactions | Types, rates, reversible, redox |
| 8. Acids, Bases & Salts | pH, indicators, neutralization, titration |
| 9. The Periodic Table | Groups, trends, metals/nonmetals |
| 10. Metals | Extraction, reactivity, corrosion |
| 11. Air and Water | Water treatment, air pollution |
| 12. Sulfur, Carbonates, Organic Chemistry | Sulfur, carbonates, organic basics |
IGCSE Chemistry: Chapter-wise Formulas, Facts & Worked Examples
1. The Particulate Nature of Matter
- Matter: made of particles (atoms, ions, molecules)
- States: solid, liquid, gas; Interparticle spacing increases → solid < liquid < gas
- Diffusion: movement from high to low concentration
Worked Example:
Explain why gases diffuse faster than liquids.
Solution: Gas particles move more rapidly and have more space between them, allowing faster mixing.
Common Mistakes & Exam Tips:
Explain why gases diffuse faster than liquids.
Solution: Gas particles move more rapidly and have more space between them, allowing faster mixing.
- Always refer to “particle movement” in explanations.
- Do not confuse changes of state with chemical change.
2. Experimental Techniques
- Filtration: separates insoluble solids from liquids.
- Evaporation: separates dissolved solids from solutions.
- Simple & Fractional Distillation: separates liquids by boiling points.
- Chromatography: separates mixtures based on solubility.
Worked Example:
How would you obtain pure water from salty water?
Solution: Use simple distillation—boil to evaporate water, then condense to collect pure water.
Common Mistakes & Exam Tips:
How would you obtain pure water from salty water?
Solution: Use simple distillation—boil to evaporate water, then condense to collect pure water.
- Chromatography: always use pencil for baseline (pen may run).
- Label solvent, residue, and filtrate in diagrams.
3. Atoms, Elements & Compounds
- Atomic Number = No. of protons, Mass Number = protons + neutrons
- Isotopes: atoms of same element, different neutrons
- Ionic Bonding: transfer of electrons; Covalent Bonding: sharing electrons
Worked Example:
A magnesium atom has 12 protons and 12 neutrons. What is its mass number?
Solution: 12 + 12 = 24.
Common Mistakes & Exam Tips:
A magnesium atom has 12 protons and 12 neutrons. What is its mass number?
Solution: 12 + 12 = 24.
- Don’t mix up mass number and atomic number.
- Remember: metals form positive ions, nonmetals form negative ions.
4. Stoichiometry
- Moles = mass / Mr
- Concentration = moles / volume (dm³)
- Volume (gas at rtp) = moles × 24 dm³
Worked Example:
How many moles in 10g NaOH (Mr = 40)?
Solution: 10 / 40 = 0.25 mol
How many moles in 10g NaOH (Mr = 40)?
Solution: 10 / 40 = 0.25 mol
Worked Example:
What volume of O2 (at rtp) does 0.5 mol occupy?
Solution: 0.5 × 24 = 12 dm³
Common Mistakes & Exam Tips:
What volume of O2 (at rtp) does 0.5 mol occupy?
Solution: 0.5 × 24 = 12 dm³
- Check units! Convert cm³ to dm³ by dividing by 1000.
- Use the periodic table for accurate relative atomic masses.
5. Electricity & Chemistry
- Electrolysis: Decomposition using electricity
- At cathode: reduction (gain of e⁻), at anode: oxidation (loss of e⁻)
- Half-equations: show electron transfer
Worked Example:
Write half-equation for formation of hydrogen at cathode in electrolysis of acidified water.
Solution: 2H⁺ + 2e⁻ → H₂(g)
Common Mistakes & Exam Tips:
Write half-equation for formation of hydrogen at cathode in electrolysis of acidified water.
Solution: 2H⁺ + 2e⁻ → H₂(g)
- Always balance charges and atoms in half-equations.
- Identify products at each electrode for given electrolytes.
6. Chemical Energetics
- Exothermic: gives out heat (ΔH negative), Endothermic: takes in heat (ΔH positive)
- Enthalpy change (ΔH), Calorimetry: Q = m × c × ΔT
Worked Example:
Calculate heat absorbed when 100g water (c = 4.2 J/g°C) is heated by 10°C.
Solution: Q = 100 × 4.2 × 10 = 4200 J
Common Mistakes & Exam Tips:
Calculate heat absorbed when 100g water (c = 4.2 J/g°C) is heated by 10°C.
Solution: Q = 100 × 4.2 × 10 = 4200 J
- State if reaction is exo/endothermic (use “ΔH sign”!).
- Watch out for unit conversions (g to kg, °C to K).
7. Chemical Reactions
- Types: combustion, decomposition, displacement, precipitation
- Redox: oxidation (loss of e⁻), reduction (gain of e⁻)
- Rates: increased by higher temp, concentration, surface area, catalyst
Worked Example:
What happens to rate if temperature increases?
Solution: Rate increases due to more frequent and energetic collisions.
Common Mistakes & Exam Tips:
What happens to rate if temperature increases?
Solution: Rate increases due to more frequent and energetic collisions.
- Explain rate changes using “collision theory.”
- Don’t mix up oxidation and reduction!
8. Acids, Bases & Salts
- Acid: releases H⁺ in water; Base: accepts H⁺ or releases OH⁻
- pH scale: 0 (strong acid) to 14 (strong alkali); pH = –log[H⁺]
- Neutralization: Acid + Base → Salt + Water
- Titration: calculate concentration using burette readings
Worked Example:
If 25cm³ HCl is neutralized by 50cm³ NaOH of same concentration, which is stronger?
Solution: Both are equally strong as they neutralize each other in a 1:2 ratio.
Common Mistakes & Exam Tips:
If 25cm³ HCl is neutralized by 50cm³ NaOH of same concentration, which is stronger?
Solution: Both are equally strong as they neutralize each other in a 1:2 ratio.
- Units: Always convert cm³ to dm³ (divide by 1000) for concentration.
- Show balanced equation in titration calculations.
9. The Periodic Table
- Groups: columns (similar properties); Periods: rows (same no. of shells)
- Group I: Alkali metals; Group VII: Halogens; Group 0: Noble gases
- Metals (left), non-metals (right), metalloids (staircase)
Worked Example:
Why are noble gases unreactive?
Solution: They have a full outer electron shell (stable).
Common Mistakes & Exam Tips:
Why are noble gases unreactive?
Solution: They have a full outer electron shell (stable).
- Don’t mix up group number with number of electrons in shell for transition elements.
- Learn trends for reactivity and melting points!
10. Metals
- Extraction: e.g., iron by blast furnace, aluminium by electrolysis
- Properties: good conductors, malleable, ductile, sonorous
- Corrosion: iron rusts (needs water and oxygen); prevention by painting, galvanizing
Worked Example:
Write a word equation for rusting of iron.
Solution: Iron + Oxygen + Water → Hydrated Iron(III) oxide
Common Mistakes & Exam Tips:
Write a word equation for rusting of iron.
Solution: Iron + Oxygen + Water → Hydrated Iron(III) oxide
- Extraction method depends on reactivity series (don’t forget carbon and hydrogen as benchmarks).
- “Alloy” = mixture of metals (not compound!)
11. Air and Water
- Water treatment: filtration, chlorination, distillation
- Pollutants: CO, SO₂, NOₓ, lead compounds—sources and effects
- Tests for water: anhydrous copper(II) sulfate turns blue, cobalt chloride turns pink
Worked Example:
How do you test for pure water?
Solution: Boiling point is exactly 100°C; use chemical tests above.
Common Mistakes & Exam Tips:
How do you test for pure water?
Solution: Boiling point is exactly 100°C; use chemical tests above.
- Don’t confuse hard and soft water (know removal methods).
- State both “source” and “effect” for each air pollutant.
12. Sulfur, Carbonates, Organic Chemistry
- Sulfur: manufacture of H₂SO₄ (Contact process), uses in industry
- Carbonates: lime (CaO), limestone (CaCO₃), slaked lime (Ca(OH)₂)
- Organic chemistry: see next section!
Worked Example:
Write the reaction for thermal decomposition of CaCO₃.
Solution: CaCO₃(s) → CaO(s) + CO₂(g) [on heating]
Common Mistakes & Exam Tips:
Write the reaction for thermal decomposition of CaCO₃.
Solution: CaCO₃(s) → CaO(s) + CO₂(g) [on heating]
- For Contact process, always mention catalyst (V₂O₅) and temp (450°C).
- “Slaked lime” is Ca(OH)₂, not CaCO₃!
IGCSE Organic Chemistry Reactions & Shortcuts
- Alkanes (CnH₂n+₂): Saturated, single bonds. Substitution (Cl₂ + UV → chloroalkane).
- Alkenes (CnH₂n): Unsaturated, double bond. Addition reactions:
Alkene + H₂ → Alkane (Ni catalyst, heat)
Alkene + Br₂ → Dibromoalkane (orange to colourless)
Alkene + H₂O (steam) → Alcohol (H₃PO₄, 300°C) - Alcohols: Combustion: C₂H₅OH + O₂ → CO₂ + H₂O
Oxidation: Alcohol + [O] → Carboxylic acid (acidified KMnO₄ or K₂Cr₂O₇) - Carboxylic Acids: Acid properties; react with carbonates, metals, bases to form salt + CO₂/H₂/water.
Worked Example:
What is observed when ethene reacts with bromine water?
Solution: Orange colour of bromine water decolorizes—test for unsaturation (alkene).
Common Mistakes & Exam Tips:
What is observed when ethene reacts with bromine water?
Solution: Orange colour of bromine water decolorizes—test for unsaturation (alkene).
- Distinguish addition (alkenes) vs. substitution (alkanes).
- Conditions (catalyst, temperature) must be quoted for full marks.
Summary Tables & SI Units
| Quantity | Formula / Unit | SI Unit |
|---|---|---|
| Mole | mass / Mr | mol |
| Concentration | mol / dm³ | mol/dm³ |
| Volume (gas at rtp) | moles × 24 | dm³ |
| Mass | - | grams (g) |
| Energy | Q = m × c × ΔT | Joule (J) |
| Pressure | P = F / A | Pascal (Pa) |
| Temperature | K = °C + 273 | Kelvin (K) |
Key IGCSE Chemistry Definitions & Laws
- Element: Substance made of only one kind of atom.
- Compound: Substance with atoms of different elements chemically combined.
- Mixture: Two or more substances physically mixed, not chemically combined.
- Isotope: Atoms of the same element with different numbers of neutrons.
- Acid: Substance that forms H⁺ ions in water; pH less than 7.
- Base: Substance that forms OH⁻ ions in water; pH greater than 7.
- Salt: Compound formed from acid-base neutralization.
- Oxidation: Loss of electrons.
- Reduction: Gain of electrons.
- Catalyst: Substance that speeds up a reaction without being changed itself.
- Electrolysis: Decomposition using electricity.
- Enthalpy Change (ΔH): Heat change at constant pressure.
How to Revise IGCSE Chemistry Effectively
- Make your own summary/formula sheet for every topic
- Practice calculations—always write units and show all working
- Memorize colors of common ions, gases, and test results
- Review common ions and their charges (especially for formulas!)
- Revise the order of reactivity series, group trends, and organic functional groups
- Do lots of past paper questions for each topic and mark them yourself
- Always review mark schemes—note keywords needed for full marks
Tip: Go through this page before every test—focus on equations, organic reactions, and common mistakes for maximum marks!
Frequently Asked Questions (FAQs) – IGCSE Chemistry Formulas
- Q1. Is this enough for scoring high in IGCSE Chemistry?
If you master these formulas, facts, and tips—and practice past papers—you will score well. Check your syllabus for updates! - Q2. Which topics are most important?
Moles & calculations, chemical reactions, acids-bases, organic chemistry, and periodic trends. Practice every calculation type! - Q3. Do I need to remember units for all quantities?
Yes—units are required for full marks, especially in calculations and tables. - Q4. How should I practice?
Use these tables to solve past paper questions, check mark schemes, and test yourself on definitions and formulas.
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