Unit 5: Materials and Their
Structure
• Objective: Understand the structure of matter,
atomic theory, purity, climate concepts, and
environmental impact.
• Keywords: atom, purity, weather, climate,
atmosphere, fossil fuels
What is an Atom?
• Atoms are the building blocks of matter.
• Made of 3 subatomic particles: Proton (+),
Neutron (0), Electron (-)
• Nucleus = center (protons + neutrons)
• Electrons orbit nucleus
Atomic History
• 1890s: J.J. Thompson – Plum Pudding Model
• 1911: Rutherford – Nucleus discovered
• 1932: Chadwick – Neutrons discovered
• Current Model: Protons & Neutrons in
nucleus, electrons in shells
Purity and Mixtures
• Pure substance = one type of particle
• Mixture = more than one substance
• Example: 24K gold = pure; 18K gold = alloy
• % Purity = (mass of pure substance / total
mass) × 100
Investigating Salt in Seawater
• Seawater contains multiple salts
• 68% = sodium chloride
• Evaporation method: leave water, collect salts
What is Weather? What is Climate?
• Weather: short-term conditions (temp, rain,
wind)
• Climate: long-term average of weather
• Meteorology = study of weather
• Climatology = study of climate
Climate Zones Around the World
• Polar, Temperate, Tropical, Arid,
Mediterranean
• Activity: Identify countries in each zone
Ice Ages and Climate Cycles
• Glacial = very cold
• Interglacial = warmer
• Ice ages = long periods of cooling
• Evidence: rock formations, fossils, pollen cores
Atmosphere Then and Now
• Early atmosphere: CO2-rich, no O2
• Today: 78% N2, 21% O2, 0.04% CO2
• Change due to photosynthesis & fossil fuel
formation
Greenhouse Effect & Global
Warming
• Gases trap heat like a blanket
• CO2, CH4, H2O = greenhouse gases
• More fossil fuel use = more warming
Renewable vs Non-Renewable
Resources
• Renewable: solar, wind, tidal
• Non-renewable: coal, oil, gas
• Need to reduce emissions
Debate on Climate Change
• Group task: prepare arguments
• Side A: Human-caused warming
• Side B: Natural cycles
• Goal: Use evidence from unit to support
claims
Review & Recap
• Key concepts:
• - Atomic structure
• - Purity & mixtures
• - Weather vs climate
• - Ice ages
• - Atmosphere & global warming
Assessment Preparation
• Focus areas:
• - Diagrams (atom, climate zones, greenhouse
effect)
• - Data interpretation (graphs, tables)
• - Scientific explanations with evidence
• Tip: Use models and analogies in your answers
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