Welcome to Chemistry 121

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Welcome to Chemistry 121
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Syllabus

• http//www.albion.edu/chemistry/abeilstein/121/F07
  

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What is chemistry all about?

• Observe changes (macroscopic properties)
• Color, taste, wavelength emitted/absorbed, change
  in temperature, change in physical state
• Understand unobservable causes (atomic/molecular
  properties and behavior)
• What makes it that way?

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Types of changes
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Check-in questions

• If I drive my car until the "empty gas tank"
  light comes on (I am not recommending you try
  this!), it can then be filled with 15.3 gallons
  of gas.  How many liters of gasoline is this?

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Check-in

• My idea of perfect weather is a sunny, 77 degree
  (Fahrenheit) day with a light breeze.  What
  temperature is this on the Celcius scale?What
  temperature is this in Kelvin?

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Check-in

• My house is a short walk to campus (0.50 miles to
  my office).  How many meters is this?

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Law of Definite Composition

• No matter what its source, a particular compound
  is composed of the same elements in the same
  parts (fractions) by mass
• In other words, a pure substance will have a
  fixed mass of a particular element

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Law of Multiple Proportions

• If elements A and B react to form 2 compounds,
  the different masses of B that combine with a
  fixed mass of A can be expressed as a ratio of
  small whole numbers
• The compounds differ in the number of atoms of
  each kind that combine

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Check-in

• In a series of experiments, a chemist prepared
  three different compounds that contain only
  iodine and fluorine and determined the mass of
  each element in each compound 
• compound 1   ________ Fcompound 2   ________
  Fcompound 3   ________ F
• The formulas of these compounds are IF5, IF7, and
  IF3, in no particular order.  Assign a formula to
  each compound and briefly explain your reasoning.

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Law of Mass Conservation

• The total mass of substances does not change
  during a chemical reaction
• Number of substances may change
• Their chemical properties must change

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Ionic bonding
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Ionic bonding
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Figure 2.14
The relationship between ions formed and the
nearest noble gas.
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Ionic bonding
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Polyatomic ion
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Covalent bonding
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Ions formed by some of the elements
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Name the following

• NiCl2               
• NiCl2.6H2O   
• K2SO4           
• NH4Br           
• CF4               
• HI                   
• NaH               

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Check-in

• As you've probably noticed, the prefixes in table
  2.6 are not used very often.  What types of
  compounds require the use of these prefixes? 
• Why are the prefixes needed for these compounds
  but not for others?

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Mole

• SI unit for amount of substance
• Used for counting (pair, dozen, score)
• Amount of a substance that contains the same
  number of entities as there are atoms in exactly
  12 g of carbon-12
• Avogadros number, NA 6.022 x 1023

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Mass

• Atomic mass of an element or molecular mass of a
  molecule in atomic mass units is numerically
  equivalent to the molar mass expressed in grams
• Mass of one Ne atom 20.18 amu (on average)
  mass of a mole of Ne atoms 20.18 grams
• Molar mass (M) of Ne is 20.18 g/mol
• Also works for molecules
• Mass of C3H8O3 molecule 92.093 amumass of a
  mole of C3H8O3 molecules 92.093 g/mol