Chemistry

Key Concepts in Chemistry

  1. Types of Substances:

    • Pure Substance: Contains only one type of particle (e.g., Oxygen gas, O₂).

    • Compound: Made of two or more elements chemically combined (e.g., Water, H₂O).

    • Solution: Homogeneous mixture with evenly distributed components (e.g., Saltwater).

    • Mechanical Mixture: Heterogeneous mixture with uneven distribution (e.g., Trail mix).

  2. Physical vs. Chemical Properties:

    • Physical Property: Observed without changing the substance (e.g., Water's density, 1 g/mL).

    • Chemical Property: Describes a substance's ability to undergo a chemical change (e.g., Iron rusting).

  3. Signs of Chemical Change:

    • Change in color.

    • Formation of gas (bubbles).

    • Production of heat/light.

    • Formation of a precipitate.

    • Irreversibility (e.g., overcooked steak).

  4. Scientific Method Steps:

    1. Observation

    2. Question/Problem

    3. Hypothesis

    4. Experiment

    5. Analysis and Conclusion

  5. Elements and Compounds:

    • Element: Pure substance with one type of atom (e.g., Gold, Au).

    • Compound: Made of two or more elements (e.g., H₂O, CO₂).

  6. Metallic vs. Non-Metallic Elements:

    • Metallic: e.g., Sodium (Na)

    • Non-metallic: e.g., Chlorine (Cl)

    • Similarities: Specific properties; can form compounds.

    • Differences: Metals are shiny and malleable; non-metals are dull and brittle.

  7. Periodic Table:

    • Group: Vertical column with similar properties (e.g., Group 1: Alkali Metals).

    • Period: Horizontal row with progressive changes.

  8. Subatomic Particles:

    • Proton: Positively charged (in nucleus).

    • Electron: Negatively charged (orbits nucleus).

    • Neutron: Neutral particle (in nucleus).

  9. Atomic Notation:

    • Example for Sodium (Na), Potassium (K), and Neon (Ne).

  10. Chart Completion:

  • Example entries:

    • Helium (He): Atomic # 2, Mass # 4, 2 Protons, 2 Electrons, 2 Neutrons.

    • Chlorine (Cl): Atomic # 17, Mass # 35, 17 Protons, 17 Electrons, 18 Neutrons.

  1. Bohr and Lewis Dot Diagrams:

  • Begin drawing using the number of valence electrons.

  1. Isotopes:

  • Atoms of the same element with different neutron counts (e.g., Carbon-12 and Carbon-14).

  1. Mass Number vs. Atomic Number:

  • Mass Number: Total Protons + Neutrons.

  • Atomic Number: Number of Protons.

  1. Density and Volume Calculations:

  • Includes calculations for unknown blocks and volume of mercury.

  1. WHMIS Symbols:

  • Identify each symbol (e.g. Flame, skull).