Science

Chapter 5 Test Review: Matter and Classification

Matter Overview

  • Matter makes up everything in the world.

  • All matter is categorized into two main categories:

    • Pure Substances: Contain only one type of atom. Includes:

      • Elements (found on the periodic table)

      • Compounds

      • Molecules

    • Mixtures: Contain two or more types of atoms.

      • Solutions: Have one phase visible.

      • Mechanical Mixtures: Have multiple phases visible.

Elements and Compounds

  • Element: A pure substance with only one type of atom.

    • Examples: Oxygen (O), Hydrogen (H).

  • Compound: Two or more elements chemically bonded.

    • Examples: H2O (water), CO2 (carbon dioxide), NaCl (sodium chloride).

Physical and Chemical Changes

  • Physical Change: Change in form or appearance; does not create new substances.

    • Examples: Melting, boiling, dissolving, breaking, evaporation/condensation.

  • Chemical Change: Results in the formation of one or more new substances.

    • Examples: Combustion, corrosion (rusting), reactions with acids.

    • Clues of a chemical change:

      • Heat or light is produced.

      • Gas bubbles produced.

      • Precipitate is formed.

      • Change is difficult to reverse.

      • New color (as a weak clue).

    • Unquestionable clue: Formation of a new substance.

Atoms

  • Atom: The smallest unit of an element.

    • Components:

      • Protons and Neutrons located in the nucleus.

      • Electrons located in valence shells.

  • Group Number: Indicates the number of valence electrons.

  • Anion: An atom with a net negative charge; usually has a full valence shell.

Bohr-Rutherford and Lewis Dot Diagrams

  • Bohr-Rutherford Diagrams: Illustrate the arrangement of electrons in an atom.

    • Examples include diagrams for Sodium, Sulfur, Chlorine, and Potassium.

Lewis Dot Diagrams

  • Lewis Dot Diagram for Sodium: Illustrates valence electrons around the atom.

    • Example notation: Na: ••.

  • Charges for Stable Ions:

    • Calcium: +2

    • Oxygen: -2

    • Zinc: +2

    • Sulfur: -2

    • Chlorine: -1

    • Potassium: +1

Ionic Compounds

  • Ionic Compound: Formed when a positive cation (metal ion) attracts a negative anion (non-metal ion).

    • Opposites are attracted to form compounds.

  • Multivalent Ionic Compounds: Formed with transition metals (which can have multiple charges) and a non-metal.

  • Polyatomic Compounds: Contain regular or transition metals with polyatomic ions.

    • A polyatomic ion contains two or more atoms that are bonded and share a charge.

  • Molecules: Groups of ions held together by chemical bonds; involve sharing of electrons.

  • Diatomic Molecules: Composed of two of the same atom bonded together.

    • Examples: H2 (hydrogen), O2 (oxygen), Br2 (bromine).

Determining Ionic vs Molecular Compounds

  • To identify if a compound is ionic or molecular:

    • Ionic: Contains at least one metal.

    • Molecular: Contains two non-metals.

Labelling Examples

  • CaF2: Ionic

  • PCl3: Molecular

  • Al(OH)3: Ionic

  • CaH2: Ionic

Periodic Table

  • Structure:

    • Horizontal rows called Periods.

    • Vertical columns called Groups or Families (e.g., Alkali metals, Alkaline earth metals, Halogens, Noble gases).

  • Noble Gases: Do not form ions as they have a full valence shell.

  • Electron Shell Capacity: Maximum electrons per shell is 2, 8, 8 respectively.

  • Diatomic Elements: The 7 diatomic elements are: H2, O2, N2, F2, Cl2, Br2, I2.