Chapter 1 – Principles of Chemistry
• States of Matter and Atomic Structure
• IGCSE Chemistry (9–1) – Edexcel
States of Matter (1.1–1.5)
• • Solids: fixed shape, fixed volume, particles in
fixed positions
• • Liquids: fixed volume, take shape of
container, particles move over each other
• • Gases: no fixed shape or volume, particles
move freely
• • Changes of state: melting, freezing,
condensation, evaporation, sublimation
Exam-style Question
• Q: Describe the arrangement and movement
of particles in a gas.
• A: Particles in a gas are far apart and move
rapidly in all directions. They have no fixed
arrangement and can be compressed easily.
Atomic Structure (1.6–1.14)
• • Structure of atom: protons (+), neutrons (0),
electrons (−)
• • Atomic number = number of protons
• • Mass number = protons + neutrons
• • Electron arrangement by shell: 2,8,8...
• • Isotopes and relative atomic mass
Worked Example
• Sodium (Na) has atomic number 11 and mass
number 23.
• Find: Number of protons, neutrons, and
electrons.
• Solution:
• - Protons = 11
• - Neutrons = 23 − 11 = 12
• - Electrons = 11
Question & Answer
• Q: Define an isotope.
• A: Isotopes are atoms of the same element
with the same number of protons but
different numbers of neutrons.
Chapter 2 – Principles of Chemistry
• The Periodic Table and Bonding
• IGCSE Chemistry (9–1) – Edexcel
The Periodic Table (2.1–2.9)
• • Group number = number of outer electrons
• • Period number = number of electron shells
• • Metals vs. non-metals: left vs. right
• • Noble gases (Group 0): unreactive due to full
outer shell
Bonding Overview (2.10–2.23)
• • Ionic: metal + non-metal (electrons
transferred)
• • Covalent: non-metal + non-metal (electrons
shared)
• • Metallic: metal + metal (positive ions in a
sea of electrons)
Example – Ionic Bonding (NaCl)
• Na⁺ gives 1e⁻ to Cl⁻
• Dot-and-cross diagrams show transfer of
electrons
Question & Answer
• Q: What is a covalent bond?
• A: A covalent bond is a shared pair of
electrons between two non-metal atoms.
Metallic Bonding Explained
• • Positive metal ions surrounded by
delocalised electrons
• • Explains conductivity and malleability
Summary
• • States of matter
• • Atomic structure and isotopes
• • Periodic table layout
• • Three bonding types