9/28/09

Post date: Sep 27, 2009 6:7:27 PM

Bell Activity: Why do do people have different names?

• • Just like elements, we give names to compounds to separate them from other compounds

  • Naming ionic compounds

    • Ionic compounds are formed because of attractions between positive and negative ions.

      • Positive ions

        • are positive because they gave up electrons (lost negative charges)

        • are called cations

        • Are usually formed by elements on the left side of the periodic table

      • Negative ions

        • are negative because the gained electrons (gained negative charges)

        • are called anions

        • Are usually formed by elements on the right side of the periodic table

    • Naming cations

      • use the name of the element, plus the word ion

      • ion charges are determined by number of valence electrons

      • cations will have + charge, with the charge number being the same as the number of valence electrons

        • Example: Sodium, Na

          • When sodium gives up electrons, it becomes an ion called sodium ion

          • Sodium is in the first column of the periodic table, so it has 1 valence electron

          • The charge of a Sodium Ion is 1+, so the symbol for this is Na 1+

        • Example: Barium, Ba

          • When barium gives up electrons, it becomes an ion called barium ion

          • Barium is in the second column of the periodic table, so it has 2 valence electrons

          • The charge of a Barium Ion is 2+, so the symbol for this is Ba 2+

      • Some elements (transition metals) form more than one type of cation

        • With these elements, we must include some way to show which ion we're talking about

        • We do this with roman numerals to show the charge of the ion

          • Example: Iron, Fe

            • Iron can give up either 2 or 3 electrons, so it will have either a 2+ or 3+ charge

            • The Iron ion with a 2+ charge is written as Iron (II) ion

            • The Iron ion with a 3+ charge is written as Iron (III) ion

        • Below are the possible charges of the transition metals

• • • Naming Anions

      • use the name of the element, but change the ending to -ide, plus the word ion

      • ion charges are determined by valence electron numbers

      • cations will have - charges, with the number determined by how many electrons they can take

        • Example: Chlorine, Cl

          • When chlorine receives an electron, it becomes Chloride ion

          • Chlorine is in the 7th column (has 7 valence electrons). This means the chlorine takes one more electron, or one negative charge.

          • The charge for this ion, then, is 1-

          • The symbol for the Chloride Ion is Cl 1-

        • Example: Nitrogen, N

          • When Nitrogen receives an electron, it becomes Nitride ion

          • Nitrogen is in the 5th column (has 5 valence electrons). This means the Nitrogen takes 3 more electron, or 3 negative charges.

          • The charge for this ion, then, is 3-

          • The symbol for the nitride ion is N 3-

Writing formulas for ionic compounds

• • Start with a cation and an anion

  • Write the symbols (with charges) for each ion

  • Put them next to each other, with the cation first

  • Cross the charges and bring them down to subscript to show how many of each ion is involved

  • Example: Hydrogen Chloride

• • Example: Iron (III) oxide

Naming ionics assignment

• • Write the name and symbol of the ions formed by the following elements:

    • 1. Lithium

    • 2. Beryllium

    • 3. Bromine

    • 4. Sulfur

    • 5. Calcium

    • 6. Cesium

    • 7. Potassium

    • 8. Phosphorus

    • 9. Astatine

    • 10. Oxygen

      • Example: For Sodium, the name of the ion is Sodium Ion and the symbol is Na 1+

  • Given the following element symbols, write the name of the compound that each pair forms:

    • 1. Na and Cl

    • 2. H and F

    • 3. Copper (II) and O

    • 4. K and Br

    • 5. Mg and P

Given the following compound names, write the formula of each ionic compound

1. Sodium chloride

2. Hydrogen fluoride

3. Copper (II) oxide

4. Potassium bromide

5. Magnesium phosphide