Chemistry Review

Study Notes

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