1. Chapter #7 Chemical Formulas and Chemical Compounds NearingZero.net

2. Section 1 Chemical Names and Formulas Chemical Formulas C 6 H 12 O 6 Al 2 (SO 4 ) 3 Subscript indicates that there are 6 carbon atoms

3. Monatomic Ions Positive Ions 1.Write the name of the element 2.Write the word ion Na + = Sodium ion Transition elements use Roman Numerals Fe +2 = Iron (II) ion Negative Ions 1.Write the name of the element 2.Change the ending to –ide 3.Write the word ion Cl - = Chloride ion

4. Binary Ionic Compounds 2 elements= Binary Metal + nonmetal = ionic 1.Write the name of the 1 st element 2.Write the name of the 2 nd element 3.Change the ending to –ide NaCl = Sodium Chloride MgCl 2 = Magnesium Chloride

5. Stock System Uses roman numerals 1.Write the name of the 1 st element 2.Write the oxidation number of the 1 st element 3.Write the name of the 2 nd element 4.Change the ending to –ide CrF 3 = Chromium (III) Flouride NiF

6. Binary Molecular Compounds Molecular= covalent PG 212 Prefixes 1.Write the name of the 1 st element 2.Write the name of the 2 nd element 3.Change the ending to –ide 4.Put in prefixes  Only use prefixes on the 1 st element if it is more than 1 NO 2 = Nitrogen Dioxide N 2 O 3

7. Binary Acids Acids always begin with H Acids that consist of 2 elements 1.Write hydro 2.Write the 2 nd element 3.Change the ending to –ic 4.Write the word ACID HF= Hydrofluoric Acid HBr

8. Oxyacids Are acids that contain hydrogen, oxygen, and a third element.  Never use Hydro 1.Write the name of the polyatomic (pg 210) 2.Change the ending to –ic or –ous (ate -ic & ite –ous) 1.Write the word ACID H 2 SO 4 = sulfuric acid H 3 PO 4

9. Polyatomic Compounds 1.Write the name of the 1 st element 2.Write the name of the polyatomic (pg 210) NaNO 3 = Sodium Nitrate AgNO 2

10. Section 2 Oxidation Numbers Oxidation numbers- are assigned to the atoms in molecules, including molecular ions, to show the general distributions of electrons among the bonded atoms. +1 +2+3 +/- 4 -3-2

11. Oxidation numbers Rules pg 216 1.UF 6 UF 6 criss cross the numbers up Check the 2 nd element using the periodic table U= +6 F= -1 2.Polyatomic compounds do a math line +3 -8 =0 H= +1 P= 5 O=-2 +1 -2 H 3 PO 4 3.If there is an ION (charge) do a math line

12. Practice oxidation numbers GeCl 2 CS 2 ClO 3 - H 2 SO 4 PCl 3 HNO 3 GeO SO 4 -2 NO 2 -

13. Section 3 Using Chemical Formulas Formula mass (molar mass or weight) of any compound or polyatomic ion is the sum of the average atomic masses of all the atoms represented in the formula. H 2 0 H x 2= 2.014g O x 1 = 15.999g 18.013 g of H 2 O

14. Old stuff Mole to grams Grams to moles Moles to particles Particles to moles Grams to particles Particles to grams

15. Percent Composition % comp= Mass of element in the sample mass of sample (formula mass) Calculate the % comp of H 2 O X 100

16. Section 4 Determining Chemical Formulas Empirical Formula- (simplest formula) consists of the symbols for the elements combined in a compound, with subscripts showing the smallest whole-number mole ratio of the different atoms in the compound. C 2 H 6 simplest formula would be CH 3

17. Empirical Formulas 1.Drop the % signs and add grams 2.Covert to moles of each element 3.Take the smallest number of moles and divide it into all the other values 4.Write the formula Determine the empirical formula for a sample that contains 78.1% B & 21.9% H

18. Molecular Formulas Do the same 4 steps for determining empirical formulas 5.Add up the formula mass of the empirical formula 6.Use the molecular formula mass in the question 7.Use the formula X= Molecular formula mass empirical formula mass 8.Use the x and multiply your empirical formula using it

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