Chapter 7_1and 2_3_Foundations of Chemistry_States of Matter (2)

Foundations of Chemistry

Lessons 1 and 2 Condensed Version

Classifying Matter

Learning Goals

• Be able to:

  • Describe matter, atoms, substances, and compounds with examples.

  • Distinguish between types of mixtures, explain differences, and provide examples.

  • Differentiate states of matter, physical and chemical changes, and outline physical properties of matter.

A. Understanding Matter

• Matter: Anything that has mass and occupies space.

  • Atom: Smallest particle and the fundamental building block of matter.

B. Atoms

• Structure: Composed of three subatomic particles:

  • Proton: Positively charged particle.

  • Neutron: No charge (neutral particle).

  • Electron: Negatively charged particle.

• Nucleus: Center of the atom containing protons and neutrons.

C. Substances

• Substance: Matter with a uniform composition.

  • Element: Contains only one type of atom.

  • Compound: Consists of two or more different elements chemically bonded together.

  • Chemical formula: A representation of a compound using symbols and numbers.

  • Symbols show different elements and subscripts show quantity.

  • Properties of compounds differ from those of their constituent elements.

D. Mixtures

• Mixture: Matter that combines physically and can be separated by physical means (e.g., black pepper and sugar).

  • Heterogeneous mixture: Not evenly mixed (e.g., salad).

  • Homogeneous mixture: Evenly mixed (e.g., saltwater).

E. Compounds vs. Solutions

• Compounds: Components are chemically bonded.

• Solutions: Components are physically mixed.

  • Solute: The substance in the least amount.

  • Solvent: The substance in the greatest amount (usually a liquid).

Lesson 2: Physical Properties

• Physical Property: Characteristic observable or measurable without changing the substance's identity.

  • State of matter: Solid, liquid, gas, dependent on temperature (72°F / 21°C).

  • Mass: Size-dependent; measures the amount of matter.

  • Volume: Amount of space occupied, measured in cubic centimeters (cm³) or milliliters (mL).

  • Melting Point: Temperature at which a solid becomes a liquid.

  • Boiling Point: Temperature at which a liquid becomes a gas.

  • Density: Ratio of mass to volume (D = M/V).

  • Electrical Conductivity: Ability to conduct electricity (conductors vs. insulators).

  • Solubility: Ability of a substance to dissolve in another.

• Parts of a mixture can be separated by physical means (e.g., boiling saltwater).

Lesson 3: Physical Changes

A. Physical Changes

• Identity Preservation: The matter retains its identity through size, shape, or state changes.

  • Example: Chewing food changes shape but not identity.

• Matter changes state with thermal energy changes:

  • Solid to Liquid: Added thermal energy loosens bonds.

  • Liquid to Gas: Further added thermal energy.

  • Sublimation: Solid to gas (skipping liquid state).

  • Condensation: Gas to liquid (thermal energy removed).

  • Freezing: Liquid to solid (thermal energy removed).

  • Deposition: Gas to solid.

  • Dissolving: A physical change.

• Reversible Changes: Solid to liquid and back.

• Irreversible Changes: E.g., cutting cloth.

B. Law of Conservation of Mass

• Mass is conserved in physical changes.