1/7/09

Post date: Jan 07, 2009 2:33:39 AM

Bell Activity: What words do you know that have a prefix (first part of the word) that tells about the number of something (example: bicycle - bi = 2 wheels)

• • Ionic and Covalent bonds quiz due

  • Naming Covalent Compounds

    • Slightly different from ionic compounds

  • Made from two elements on the right side of the table

    • Element farther to the left on the periodic table is named first

    • Element on right on periodic table is named second, and the ending is changed to -ide.

  • Use prefixes to tell how many of each atom is in a molecule. If there is only one of the first atom, no prefix is needed

• • • Example: One atom of Boron bonds with three atoms of fluorine, BF3

      • Boron is farther to the left, so it is named first

      • Fluorine is farther to the right, so it comes second and changes to fluoride

      • There are 3 fluorine atoms, so we put the prefix "tri" in front of fluoride

      • Name: Boron trifluoride

    • Example: Two atoms of Nitrogen bond with 4 atoms of Oxygen, N2O4

      • Nitrogen is on the left, named first

      • Oxygen is on the right, named second and changed to oxide

      • 2 Nitrogens, so use the prefix "di"

      • 4 oxygens, so use the prefix "tetra"

      • Name: Dinitrogen tetroxide

• • Naming and empirical formulas assignment

    • • Given below are either the name or the formula for covalent compounds. Complete the table with the missing names or formulas.

• • Empirical Formulas

    • Smallest ratio of atoms in a compound

    • For ionic compounds, the chemical formula is the same as the empirical formula

    • For covalent compounds, the two may or may not be the same

      • Example: H2O is the molecular formula for water. It is also the smallest ratio, so it is the empirical formula as well.

      • Example: C6H12O6 is the molecular formula for glucose. They all have a common factor of six, so if we divide the numbers by 6, we get CH2O, which is the empirical formula.

    • Using masses to find the empirical formula

      • Given the mass of a certain element in a compound for each element

      • Divide each mass by the element's atomic mass

      • smallest whole number ratio of these numbers tells number of each atom for empirical formula

      • Example: Page 196

• Naming and empirical formulas assignment

  • • Add on page 196: 1-7