science

Drawing Electron Dot Diagrams

  • Potassium and Chlorine

    • Electron dot diagram:

    • K: ( ext{K} \cdot \cdot \text{Cl} )

    • Chemical formula: ( \text{KCl} )

  • Magnesium and Iodide

    • Electron dot diagram:

    • ( \text{Mg.} \quad \text{I.} )

    • Chemical formula: ( \text{MgI}_2 )

  • Calcium and Oxygen

    • Electron dot diagram:

    • ( \text{Ca.} \quad \text{O:} )

    • Chemical formula: ( \text{CaO} )

  • Sodium and Oxygen

    • Electron dot diagram:

    • ( \text{Na.} \quad \text{O:} )

    • Chemical formula: ( \text{Na}_2O )

  • Aluminum and Chlorine

    • Electron dot diagram:

    • ( \text{Al} \quad \text{Cl:} )

    • Chemical formula: ( \text{AlCl}_3 )

  • Barium and Nitrogen

    • Electron dot diagram:

    • ( \text{Ba} \quad \text{N} )

    • Chemical formula: ( \text{Ba}3N2 )

Determining the Chemical Formula for Ionic Compounds

  1. Write down the ions of each element with charge (symbol with oxidation number)

  2. Determine the number of each ion needed to create a neutral compound (using the "crisscross applesauce" method).

  3. Write the formula using subscripts to indicate the quantity of each ion.

  4. Simplify if needed.

Example: Magnesium and Phosphorus

  • Ions: ( \text{Mg}^{2+} \quad \text{P}^{3-} )

  • Neutral compound:( ext{Mg}3 ext{P}2)

Naming Ionic Compounds

Basic Steps:

  1. Write the name of the metal (first element).

  2. Write the name of the non-metal (second element) with an -ide ending.

Examples:

  • Calcium sulfide:

    • Formula: ( \text{CaS} )

  • Sodium oxide:

    • Formula: ( \text{Na}_2 ext{O} )

Writing Names with Polyatomic Ions

  • Steps:

  1. Write the name of the first element (metal).

    • If polyatomic ion, use the special name.

  2. Write the name of the second element (nonmetal) with an -ide ending.

    • If polyatomic ion, use the special name without -ide.

Common Polyatomic Ions:

  • Ammonium: ( ext{NH}_4^+ )

  • Sulfate: ( ext{SO}_4^{2-} )

  • Nitrate: ( ext{NO}_3^- )

  • Phosphate: ( ext{PO}_4^{3-} )

Practice Examples:

  1. ( ext{NaNO}_3 ): Sodium Nitrate

  2. ( ext{CaSO}_4 ): Calcium Sulfate

  3. ( ( ext{NH}4)2 ext{O} ): Ammonium Oxide

  4. ( ext{Mg}3( ext{PO}4)_2 ): Magnesium Phosphate

  5. ( ext{NH}4 ext{NO}3 ): Ammonium Nitrate

Practice Time (Polyatomic Ions):

  • For each formula, identify the correct name using the same structure:

  1. ( ext{BaSO}_4 ): Barium Sulfate

  2. ( ext{Al}2 ext{(CO}3 ext{)}_3 ): Aluminum Carbonate

  3. ( ext{Ca(NO}3 ext{)}2 ): Calcium Nitrate

  4. ( ext{NaC}2 ext{H}3 ext{O}_2 ): Sodium Acetate

  5. ( ext{K}3 ext{PO}4 ): Potassium Phosphate

Recap of Policies for Ionic Compounds:

  • Always use parentheses for polyatomic ions when needed.

  • Charges must balance to create a neutral compound.

  • Reduce subscripts if possible to simplify the formula but do not change the internal structure of polyatomic ions.

Determining the Chemical Formula for Ionic Compounds

  1. Write down the ions of each element with charge (symbol with oxidation number).

  2. Determine the number of each ion needed to create a neutral compound (using the "crisscross applesauce" method).

  3. Write the formula using subscripts to indicate the quantity of each ion.

  4. Simplify if needed.

Example: Magnesium and Phosphorus

  • Ions: ( \text{Mg}^{2+} \quad \text{P}^{3-} )

  • Neutral compound: ( \text{Mg}3 \text{P}2 )

Naming Ionic Compounds
Basic Steps:

  1. Write the name of the metal (first element).

  2. Write the name of the non-metal (second element) with an -ide ending.

Examples:

  • Calcium sulfide:

    • Formula: ( \text{CaS} )

  • Sodium oxide:

    • Formula: ( \text{Na}_2 \text{O} )

Writing Names with Polyatomic Ions
Steps:

  1. Write the name of the first element (metal).

    • If polyatomic ion, use the special name.

  2. Write the name of the second element (nonmetal) with an -ide ending.

    • If polyatomic ion, use the special name without -ide.

Common Polyatomic Ions:

  • Ammonium: ( \text{NH}_4^+ )

  • Sulfate: ( \text{SO}_4^{2-} )

  • Nitrate: ( \text{NO}_3^- )

  • Phosphate: ( \text{PO}_4^{3-} )

Recap of Policies for Ionic Compounds:

  • Always use parentheses for polyatomic ions when needed.

  • Charges must balance to create a neutral compound.

  • Reduce subscripts if possible to simplify the formula but do not change the internal structure of poly