Grade 8: Chemistry

Here is a comprehensive overview of the Grade 8 Chemistry content, aligned with the British Columbia (BC) Curriculum.

In BC, the Grade 8 Chemistry unit is centered on the fundamental building blocks of all matter and the changes they undergo.

BC Grade 8 Science: Chemistry Unit – The Nature of Matter

This unit explores the world at the particulate level, answering the questions: “What is everything made of?” and “How and why does matter change?”

Overarching Big Ideas (for the Chemistry Unit)

• The behaviour of matter can be explained by the kinetic molecular theory and atomic theory.

• Elements are composed of one kind of atom and are the primary building blocks of matter.

Core Components of the Grade 8 Chemistry Unit

Part A: The Particle Model of Matter & Kinetic Molecular Theory

• Key Concepts: All matter is made of particles, states of matter, and energy’s role.

• Learning Goals:

  • State the main ideas of the Particle Model of Matter:

    1. All matter is made of tiny, indivisible particles.

    2. These particles are in constant, random motion.

    3. The particles have spaces between them.

    4. The particles are attracted to one another (forces of attraction).

  • Use the model to explain the properties and behaviour of the three states of matter:

    • Solid: Definite shape and volume; particles vibrate in place.

    • Liquid: Definite volume, no definite shape; particles can slide past one another.

    • Gas: No definite shape or volume; particles move quickly and are far apart.

  • Explain how adding or removing thermal energy (heating/cooling) causes changes of state (melting, freezing, evaporation, condensation, sublimation).

Part B: Atomic Theory and the Periodic Table

• Key Concepts: Atoms, elements, and the organization of the periodic table.

• Learning Goals:

  • Define an atom as the smallest unit of an element that retains its properties.

  • Define an element as a pure substance made of only one kind of atom.

  • Identify the information in a periodic table square: Atomic Number, Element Name, Chemical Symbol, and Atomic Mass.

  • Understand that the atomic number is the number of protons in an atom and defines the element.

  • Recognize that the periodic table is organized into metals, non-metals, and metalloids, and that elements in the same vertical column (group) have similar chemical properties.

Part C: Compounds, Chemical Formulas, and Reactions

• Key Concepts: How atoms combine, evidence of chemical changes.

• Learning Goals:

  • Define a compound as a pure substance formed when atoms of two or more different elements chemically combine (e.g., H₂O, CO₂).

  • Interpret simple chemical formulas (e.g., H₂O: 2 hydrogen atoms, 1 oxygen atom).

  • Differentiate between a physical change (change in state or form, no new substance, often reversible) and a chemical change (produces new substances with new properties, often irreversible).

  • Identify evidence that a chemical reaction has occurred:

    • Change in colour

    • Formation of a gas (bubbling, fizzing)

    • Formation of a precipitate (a solid forms in a liquid)

    • Energy change (production of heat or light)

Part D: The Law of Conservation of Mass

• Key Concepts: Mass is conserved in chemical reactions.

• Learning Goals:

  • State the Law of Conservation of Mass: In a chemical reaction, atoms are rearranged but not created or destroyed. Therefore, the total mass of the reactants equals the total mass of the products.

  • Explain that because atoms are just rearranged, the total number of each type of atom is the same before and after a chemical reaction.

Curricular Competencies in Action (The “Doing” of Science)

• Questioning and Predicting:

  • “If I freeze a sealed bottle of water, will its mass change? Why or why not?”

  • “What evidence would tell me if baking soda mixed with vinegar is a physical or chemical change?”

• Planning and Conducting:

  • Lab: Modeling States of Matter. Use beads in a sealed container to model the arrangement and movement of particles in a solid, liquid, and gas.

  • Investigation: Conservation of Mass. Perform a simple reaction like Alka-Seltzer in a sealed Ziploc bag or vinegar and baking soda in a closed system, measuring mass before and after to demonstrate the law.

• Processing and Analyzing Data and Information:

  • Draw particle diagrams to represent matter in different states and during changes of state.

  • Analyze simple chemical formulas to count the number of each type of atom.

• Evaluating:

  • Evaluate different models of the atom (e.g., the Bohr model vs. a fuzzy electron cloud model) and discuss their strengths and limitations.

• Applying and Innovating:

  • Contribute to care for self, others, and community by researching and explaining the chemistry behind a local environmental issue, like the effect of CO₂ (a compound) on the atmosphere.

• Communicating:

  • Use scientific language to write a clear, step-by-step explanation of what happens to the particles when water boils.

Sample Learning Standards from the BC Curriculum

• Content: “Explain the relationship between the properties of a substance and its molecular structure.”

• Content: “Explain the law of conservation of mass.”

• Content: “Distinguish between elements and compounds.”

• Curricular Competency: “Experience and interpret the local environment.” (e.g., observing physical and chemical changes in nature).

Key Connections to Other Grade 8 Science Units

• Connection to Physics (Energy): The concepts of thermal energy and energy transfer are crucial for understanding changes of state in chemistry.

• Connection to Biology: The chemical elements (especially Carbon, Hydrogen, Oxygen, Nitrogen) are the building blocks of all living things. The process of photosynthesis is a key chemical reaction in biology.

• Connection to Earth Science: The chemistry of the atmosphere (gases) and the geosphere (minerals and rocks as compounds) is fundamental to understanding Earth’s systems.

This unit provides the foundational knowledge for all future chemistry studies and empowers students to see the unseen world of atoms and molecules that makes up everything they interact with.