Molecules, Compounds and Chemical Equations by TpVChV

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									Molecules, Compounds and
   Chemical Equations

          CHM 108
         SUROVIEC
         FALL 2011
         I. Hydrogen, Oxygen and Water
                            2

 Hydrogen is an explosive gas
 Oxygen is a gas needed for burning
 Water is a very different molecule then either of
 these
3
                II. Chemical Bonds
                            4

 Hold atoms together and are a result of interactions
  of the electrons of the atoms
 2 main types of bonds
                   A. Ionic Bond
                           5

 Since metals tend to lose electrons and nonmetals
 tend to gain electrons we often see when a metal and
 a nonmetal react to make an ionic bond
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    6
               B. Covalent Bonds
                          7

 Nonmetal to nonmetal and the electrons are shared
             III. Chemical Formulas
                           8

A. Chemical Formulas: indicate the elements present
   with the relative number of atoms or ions of each.
1. Empirical Formula: gives the relative number of
   atoms of each element in a molecule
2. Molecular Formula: gives actual number of atoms
   of each element in a molecule
3. Structural Formula: uses lines to show bonds
               IV. Atomic Level View
                           9
1. Atomic elements are         3. Molecular compounds
   those that exist in           are composed of 2 or
   nature using single           more covalently bound
   atoms of an element           nonmetals

2. Molecular elements          4. Ionic compounds are
   exist as 2 or more            composed of a charged
   atoms as a basic unit         metal and nonmetal
               V. Ionic Compounds
                             10
 Ionic compounds have
 an overall charge of zero
 and many elements form
 only 1 type of ion with a
 predicable charge
          VI. Molecular Compounds
                          11

 As opposed to ionic compounds molecular
 compounds are not as straight forward to figure out
 as they can combine in several different ways
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VII. Formula Mass and Moles of Compounds
                          13

 The average mass of a molecule of a compound is its
 molecular mass
 A. Molar Mass of a Compound and Conversion
                          14

 Molar mass of a compound is the mass in grams of 1
 mole of molecules
                      Example
                           15

1.   If I have 72.5 grams of C3H8O how many molecules
     of C3H8O is this?



2. How many carbon atoms are in that many
     molecules?
       VIII. Composition of Compounds
                          16

 A chemical formula can also give additional
  information.
 The formula along with knowing the molecular
  weight of the elements can tell us about how much of
  an element is in a compound
                     Example
                          17

 Acetic acid which is CH3COOH, is an active
 ingredient in vinegar. What is the mass percent of
 the C, H, and O in acetic acid.
 C. Conversion Factors from Chemical Formulas
                           18

 Chemical formulas contain within them
 relationships between atoms and molecules.




 Given 50.0 grams of CH3COOH how many grams of
 carbon in the molecule?
     IX. Determining Chemical Formulas
                           19

 We just calculated the mass percent of acetic acid
 because we knew the formula. But what if we
 determined the formula from the mass percent?
                     Example
                          20

 Given the experimentally determined mass percents
  below what is the chemical formula?
 K = 24.75%
 Mn = 34.77%
 O = 40.51%
     A. Empirical to Molecular Formulas
                            21

 A molecular formula is just a whole number multiple
 of the empirical formula

 Example: Acetylene is the gas used in welding. It is
 92.26% carbon and 7.74% hydrogen. The molecular
 weight is 26.06g/mole. What is the empirical and
 molecular formula?
       X. Balancing Chemical Equations
                          22

 Chemical reaction is a process in which one or more
 substances are converted to different ones.
                   A. Balancing
                           23

1. Write a skeletal equation by writing formulas of
   reactant and product
2. Balance atoms that occur in more complex
   molecules
3. Balance atoms that occur as free elements
4. Check both sides for the same number of atoms

								
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