Chemistry Review - Grade 9

Chemistry Review - Grade 9

• Terms to Review: Atom, Electron, Element, Group (chemical), Ionic compound, Matter, Mechanical mixture, Molecular compounds, Neutron, Period, Proton, Pure substance, Solution, Suspension

Key Concepts

• Physical vs. Chemical Properties:

  • Diamonds are hard - physical property
  • Gallium melts in the palm of your hand - physical property
  • Wood burns easily - chemical property
  • Iron is magnetic - physical property
  • Some cleaners are corrosive - chemical property

• Boiling and Melting Points:

  • Boiling point is the temperature at which a liquid turns to a gas
  • Melting point is the temperature at which a solid turns to a liquid
  • Examples: Water's melting point converts ice to liquid water, and its boiling point turns water into water vapor.

• Melting and Particle Theory:

  • When a solid is heated, its particles gain energy
  • This overcomes the forces holding them in place, allowing the particles to move more freely, turning the solid to a liquid.

• Groups and Periods:

  • Periods are horizontal rows in the periodic table
  • Groups are vertical columns in the periodic table
  • Atomic number increases across periods and down groups

• Metals, Nonmetals & Metalloids:

  • Metals are typically on the left side of the periodic table
  • Non-metals are typically on the right side of the periodic table
  • Metalloids are located along a dividing line separating the metals and non-metals.

• Valence Electrons: Each of the elements below are listed with their relevant number of valence electrons

  • Hydrogen - 1
  • Aluminum - 3
  • Carbon - 4
  • Oxygen - 6
  • Chlorine - 7

• Ions and Ion Charges:

  • Ions are atoms that have gained or lost electrons
  • Anions are negatively charged ions
  • Cations are positively charged ions
  • The number of the ion charge crossed over becomes the subscript of the other ion in a compound.

• Metals and Ions:

  • Metals tend to lose electrons and form positively charged ions (cations)
  • Non-metals tend to gain electrons and form negatively charged ions (anions)

• Compound Names and Types:

  • Examples of compounds and their types are listed below:
    • LiCl - Lithium and Chlorine (ionic)
    • Al2S3 - Aluminum and Sulfur (ionic)
    • AgF - Silver and Fluorine (ionic)
    • ZnO - Zinc and Oxygen (ionic)
    • N2S3 - Nitrogen and Sulfur (molecular)
  • These can be identified as types, ionic or molecular, based on the elements involved

• Periodic Table Patterns

• Elements in a group have a similar number of outer electrons (electron configuration)

• Rows are arranged from left to right with increasing atomic numbers (ascending).

• Bohr Diagrams: These are diagrams that show the electron configuration of an atom (electron arrangement).

• Chemical Names of Compounds: Examples of compounds listed with their corresponding chemical names

  • MgBr2 - Magnesium bromide
  • Ba3N2 - Barium nitride
  • Ca3P2 - Calcium phosphide
  • Al2O3 - Aluminum oxide
  • NaI - Sodium iodide
  • CaCl2 - Calcium chloride
  • K2CO3 - Potassium carbonate
  • MgSO4 - Magnesium sulfate
  • Cl2O5 - Dichlorine pentaoxide

• Identifying Compounds as Ionic or Molecular: Examples of compounds and their types are listed below.

  • Mg3P2 - Magnesium Phosphide (ionic)
  • Li3N - Lithium Nitride (ionic)
  • PCl5 - Phosphorus Pentachloride (molecular)
  • AlBr3 - Aluminum Bromide (ionic)
  • CaS - Calcium Sulphide (ionic)
  • SO2 - Sulfur Dioxide (molecular)
  • KI - Potassium Iodide (ionic)
  • Na2O - Sodium Oxide (ionic)
  • Ca(OH)2 - Calcium Hydroxide (ionic)
  • Al2(CO3)3 - Aluminum Carbonate (ionic)
  • NCl3 - Nitrogen Trichloride (molecular)

• Atomic Structure Table: A table has been provided giving the relevant information for the elements listed.

  • Atomic Number
  • Atomic Mass
  • Protons
  • Neutrons