AQA GCSE Chemistry Paper 1 Overview

Introduction

• Covers topics 1-5: Atoms, Bonding, Quantitative Chemistry, and Chemical/Energy Changes.
• Applicable for Higher and Foundation Tier, Double Combined Trilogy, and Triple Separate Chemistry.
• Distinctions made for Triple and Higher Tier content.

Atoms and Substances

Basic Concepts

• Substances made of atoms (elements) represented by symbols in the periodic table.
• Compounds consist of two or more different atoms chemically bonded.
  • Example: Water (H₂O) contains hydrogen and oxygen atoms.

Chemical Reactions

• Reactions can be represented by word and symbol equations.
• Conservation of mass: same number of each type of atom on both sides of the equation.
• Balancing equations: focus on compounds first.

Mixtures and Separation Techniques

• Mixtures: combinations of elements/compounds not chemically bonded.
  • Example: Air (oxygen, nitrogen, etc.).
• Separation techniques: Filtration, Crystallization, Distillation, Fractional Distillation.
• States of matter: solid, liquid, gas; energy is required to change states.

Development of Atomic Theory

Historical Models

• JJ Thompson: Plum pudding model (positive charge with electrons).
• Ernest Rutherford: Nuclear model (nucleus existence).
• Niels Bohr: Electrons in shells or orbitals.
• James Chadwick: Discovery of neutrons.

Atomic Structure

• Atomic number (number of protons) determines element.
• Mass number = protons + neutrons.
• Isotopes: same element, different numbers of neutrons.

The Periodic Table

Development and Structure

• Early tables based on atomic weight and properties.
• Dmitri Mendeleev: Organized by properties, predicted undiscovered elements.

Electron Configuration and Groups

• Electrons exist in shells, max 2 on 1st shell, 8 on others.
• Metals (left of staircase) donate electrons, non-metals (right) accept electrons.
• Group number indicates number of outer shell electrons.

Bonding

Types of Bonds

• Metallic bonding: Metal atoms sharing delocalized electrons.
• Ionic bonding: Between metals and non-metals (transfer of electrons).
  • Example: NaCl (sodium chloride) is formed by sodium donating an electron to chlorine.
• Covalent bonding: Non-metals sharing electrons to form molecules.

Bond Properties

• Ionic compounds: high melting/boiling points, conduct electricity when molten.
• Covalent compounds: simple covalent (low boiling points) and giant covalent (like diamond, high melting points).

Quantitative Chemistry

Relative Mass and Moles

• Conservation of mass in reactions.
• Relative atomic mass and relative formula mass.
• Moles as a measure of substance amount (moles = mass/RAM).

Stoichiometry and Calculations

• Use balanced equations to calculate mass and moles.
• Limiting reactants determine the amount of product.
• Concentration conversions: grams per decimeter cubed or moles per decimeter cubed.

Chemical Changes

Reactivity Series

• Metals compared to hydrogen and carbon for extraction.
• More reactive metal displaces less reactive metal.

Oxidation and Reduction

• Oxidation is loss, reduction is gain of electrons.
• Metal extraction using carbon (smelting).

Acids, Bases, and Salts

• Acid + base reactions produce salts.
• pH scale is logarithmic; strong vs. weak acids.

Energy Changes

Exothermic and Endothermic Reactions

• Exothermic: releases more energy, increases temp.
• Endothermic: requires more energy, decreases temp.

Bond Energy and Reaction Profiles

• Energy needed to break/make bonds indicates reaction type.
• Activation energy: energy barrier for reaction initiation.

Electrolysis

• Conduct electricity by moving ions in molten/solution state.
• Extraction methods for metals less reactive than carbon.

Additional Concepts for Triple

Nanoparticles

• Surface area to volume ratio significance.

Titrations

• Determine concentration using neutralization reactions.

Cells and Fuel Cells

• Batteries and fuel cells as energy sources.

Conclusion

• Review all topics thoroughly for exams.
• Utilize playlists and additional resources for deeper understanding.