chem

A) Key Terms & Definitions:

• Accuracy: How close a measurement is to the accepted value.

• Precision: How close multiple measurements are to each other.

• Matter: Anything that has mass and takes up space.

• Element: A pure substance that cannot be broken down into simpler substances.

• Compound: A pure substance made of two or more elements chemically bonded.

• Mixture: A combination of two or more substances that are not chemically bonded.

• Physical Property: Observable without changing composition (e.g., color, density, melting point).

• Chemical Property: Describes how a substance reacts (e.g., flammability, reactivity).

• Physical Change: A change that does not alter the substance’s identity (e.g., melting, dissolving).

• Chemical Change: A change where a new substance is formed (e.g., rusting, combustion).

• WHMIS (Workplace Hazardous Materials Information System): A system for classifying and labeling hazardous materials.

• Scientific Notation: A way of writing very large or small numbers using powers of ten (e.g., 3.0 × 10³).

• Significant Digits: The meaningful digits in a number, based on measurement accuracy.

• STSE (Science, Technology, Society, and Environment): Connections between scientific concepts and real-world applications.

• Empirical Knowledge: Knowledge from experimentation and observation.

• Theoretical Knowledge: Knowledge based on scientific explanations and models.

• Theory: An explanation based on evidence that can be revised or discarded.

• IUPAC (International Union of Pure and Applied Chemistry): Organization that standardizes chemical terminology and practices.

B) Major Topics:

1. The Nature of Chemistry

• Chemistry is the study of matter, its composition, and how substances interact.

• Chemistry is known as the Central Science, as it connects biology, physics, and other sciences.

• Branches of chemistry include organic, inorganic, nuclear, environmental, biochemistry, physical, and analytical chemistry.

• Chemistry is practical and impacts daily life, from medicine to food production.

2. WHMIS & Safety in the Lab

• WHMIS is used across Canada, while GHS (Globally Harmonized System) is used internationally.

• Three parts of WHMIS:

  1. Labels (English & French, pictograms, cautionary sentences).

  2. SDS Sheets (16-section safety data sheets).

  3. Training (education on chemical handling and safety).

• WHMIS Symbols & Hazards:

  • Exploding Bomb: Explosion hazard.

  • Flame: Fire hazard (e.g., gasoline).

  • Oxidizing Agent: Causes fire (e.g., H2O2).

  • Toxicity: Poisonous (e.g., rat poison).

  • Environmental Toxin: Damages the environment (e.g., oil spill).

  • Health Hazard: Causes serious health problems (e.g., carcinogens).

  • Gas Cylinder: May explode if heated (e.g., oxygen gas).

  • Corrosive: Causes burns (e.g., sulfuric acid).

  • Biohazard: Infectious materials (e.g., blood).

3. Properties of Matter

• Physical Properties: Observable without changing composition (e.g., boiling point, density).

• Chemical Properties: Describe how a substance reacts (e.g., reactivity with acid).

4. States of Matter

• Solid: Definite shape and volume.

• Liquid: Definite volume, takes shape of the container.

• Gas: No definite shape or volume.

5. Physical vs. Chemical Changes

• Physical Changes: No new substance (e.g., melting, freezing, cutting).

• Chemical Changes: New substance formed (e.g., burning, rusting).

6. Classifying Matter (Flow Diagrams)

• Pure substances: Elements & compounds.

• Mixtures: Homogeneous (uniform) & heterogeneous (not uniform).

7. Conversions (Metric System)

• Basic units: grams (g), meters (m), liters (L).

• Conversion example: 1 km = 1000 m, 1 g = 1000 mg.

8. Significant Digits Rules

• Non-zero digits are always significant.

• Zeros between non-zero digits are significant.

• Leading zeros are NOT significant.

• Trailing zeros in a decimal are significant.

9. Accuracy vs. Precision

• Accuracy: How close a measurement is to the actual value.

• Precision: How consistent multiple measurements are.

10. Scientific Notation

• Express large/small numbers in the form: a × 10ⁿ.

  • Example: 0.00042 → 4.2 × 10⁻⁴

11. Types of Errors in Science

• Random Errors: Caused by unpredictable variations; reduced by repeated trials.

• Systematic Errors: Due to equipment flaws or design flaws. Cannot be corrected by repetition.

C) Atoms and Their Composition

1. History of the Atom (Scientists & Models)

• Dalton: Atoms are indivisible particles (wrong).

• Thomson: Discovered electrons (plum pudding model).

• Rutherford: Gold foil experiment, discovered nucleus.

• Bohr: Electrons in energy levels.

• Schrödinger: Quantum mechanical model.

2. Atomic Structure

• Atomic Number (Z): Number of protons.

• Mass Number (A): Protons + neutrons.

• Isotopes: Same element, different number of neutrons.

• Radioisotopes: Unstable isotopes that decay over time.

3. Standard Notation

Example:

(A = mass number, Z = atomic number).