IGCSE Chemistry Extended Revision Notes and Exam Questions
1. States of Matter
- Solids: Fixed shape and volume, particles vibrate in place.
- Liquids: Fixed volume, shape of container, particles slide past each other.
- Gases: No fixed shape/volume, particles move rapidly and randomly.
- Changes of state: melting, boiling, condensing, freezing, sublimation.
- Interconversion involves energy and changes in particle movement.
2. Experimental Techniques & Chemical Analysis
- Filtration: separates insoluble solids from liquids.
- Crystallisation: separates dissolved solids from liquids by evaporation.
- Distillation: separates liquids based on boiling points.
- Chromatography: separates mixtures based on solubility.
- Purity: pure substances have fixed melting/boiling points.
- Rf value = distance moved by substance / distance moved by solvent.
3. Atoms, Elements, and Compounds
- Atom: smallest unit of an element, consists of protons, neutrons, electrons.
- Atomic number = number of protons.
- Mass number = protons + neutrons.
- Isotopes: atoms with same atomic number, different mass numbers.
- Compounds: formed from chemical bonding between elements.
4. The Periodic Table
- Elements arranged by increasing atomic number.
- Groups: vertical columns, same number of outer electrons.
- Periods: horizontal rows, increasing energy levels.
- Group I: Alkali metals reactive, soft, react with water.
- Group VII: Halogens reactive non-metals, form salts with metals.
- Group 0: Noble gases inert, full outer shells.
5. Stoichiometry
- Relative atomic mass (Ar), relative molecular mass (Mr).
- Mole = mass / Mr.
- Balanced equations: conservation of mass.
- Reacting masses: use mole ratios.
- Empirical formula: simplest whole-number ratio of atoms.
- Molecular formula: actual number of atoms.
IGCSE Chemistry Extended Revision Notes and Exam Questions
Exam-style Questions and Answers
Q1: Describe the differences in arrangement and movement of particles in solids, liquids and gases.
A1: Solids particles tightly packed, vibrate in place. Liquids close together, move over each other. Gases far apart,
move randomly and quickly.
Q2: A student uses chromatography to test ink. The solvent moves 8cm, ink 4cm. Calculate Rf.
A2: Rf = 4 / 8 = 0.5.
Q3: What is the empirical formula of a compound with 40% sulfur and 60% oxygen?
A3: S: 40/32 = 1.25; O: 60/16 = 3.75 divide by 1.25 S1O3.
Q4: Balance: ___H2 + ___O2 ___H2O.
A4: 2H2 + O2 2H2O.
Q5: What are the properties of group I elements?
A5: Soft, low melting points, reactive with water, form alkaline solutions.