9/29/09
Post date: Sep 28, 2009 8:40:56 PM
Bell Ringer: Write the formulas for Lithium oxide, Calcium bromide, and Iron (III) chloride.
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 covalents 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 covalents assignment
Add on page 196: 1-7