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Key Concepts for AQA GCSE Chemistry

May 15, 2025

AQA GCSE Chemistry Paper 1 Overview

Topics Covered

  • Atoms
  • Bonding
  • Quantitative Chemistry
  • Chemical and Energy Changes

Substances and Reactions

  • Atoms and Elements: Represented by symbols in the periodic table.
  • Compounds: Substances with two or more different atoms chemically bonded (e.g., H2O).
  • Mixtures: Combinations of elements/compounds not chemically bonded (e.g., air).
    • Filtration: Separates solids from liquids.
    • Distillation: Separates liquids based on boiling points.

States of Matter

  • Solid: Particles vibrate in fixed positions.
  • Liquid: Particles move past each other.
  • Gas: Particles far apart and move randomly.
  • State Changes: Physical processes; no new substances are made.
  • State Symbols: (s) solid, (l) liquid, (g) gas, (aq) aqueous.

Atomic Theories

  • JJ Thompson: Plum pudding model.
  • Ernest Rutherford: Nucleus discovery.
  • Niels Bohr: Electron shells.
  • James Chadwick: Neutrons.

The Periodic Table

  • Atomic Number: Number of protons.
  • Mass Number (RAM): Protons + Neutrons.
  • Isotopes: Same element, different neutrons.
  • Arrangement: Based on atomic number and properties.

Electron Configuration

  • Electrons fill shells: Each shell has a maximum capacity (2, 8, 8, 2).
  • Transition metals have complex configurations.

Chemical Bonding

  • Metallic Bonding: Delocalized electrons around a lattice.
  • Ionic Bonding: Metal donates electrons to nonmetals.
    • Ionic compounds form crystal lattices and conduct electricity when liquid.
  • Covalent Bonding: Nonmetals share electrons.
    • Simple covalent have low melting points; giant covalent (e.g., diamond) have high melting points.
  • Molecular Ions: E.g., hydroxide (OH-).

Quantitative Chemistry

  • Conservation of Mass: Mass is conserved in reactions.
  • Relative Atomic/Formular Mass: Sum of atomic masses.
  • Moles: Measure of substance amount.
    • Equation: Moles = Mass/RAM.

Chemical Changes

  • Reactivity Series: Metals compared for reactivity.
  • Displacement: More reactive metal displaces less reactive.
  • Reduction/Oxidation (Redox): OIL RIG - Oxidation Is Loss, Reduction Is Gain of electrons.
  • Acids and Bases: Neutralization results in salt and water.

Energy Changes

  • Exothermic: Releases energy (e.g., combustion).
  • Endothermic: Absorbs energy.
  • Energy Profiles: Show energy changes in reactions.

Triple Only

  • Nanoparticles: High surface-to-volume ratio, significant in reactions.
  • Titrations: Determine concentrations in solutions.
  • Electrolysis: Splits compounds using electricity; metals purified/extracted.
  • Fuel Cells: Use hydrogen and oxygen to produce electricity.

Conclusion

  • This summary provides an overview of key concepts for AQA GCSE Chemistry Paper 1. Understanding these foundational principles is crucial for success in the exam.