Topic: Chemical Formulas

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Topic Chemical Formulas
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Subscripts in Chemical Formulas

• numbers inside formulas
• lowered below line of type
• show of atoms of each element
• No subscript understood to be 1
• S8
• 8 is the subscript, so there are 8 Sulfur toms

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Chemical Formulas

• H2O has 2 hydrogens and 1 oxygen
• NH3 has 1 nitrogen and 3 hydrogens
• CH4 has ?
• CO2 has ?
• AgNO3 has ?

1 carbon and 4 hydrogen
1 carbon and 2 oxygen
1 silver, 1 nitrogen, 3 oxygen
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atoms in formulas
Subscript outside ( ) multiplied by subscript
inside ( ) of atoms

• Al(NO3)3
• Al
• N
• O
• Total

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Coefficients

• Numbers in front of formulas
• Refers to everything following in formula
• No coefficient? Its understood to be 1
• 4CO2
• 4 is the coefficient

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Coefficients

• 2H2O means 2(H2O)
• To count atoms -
• multiply coefficient x subscript
• 2 x 2 4 Hs
• 2 x 1 2 Os

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Chemical Formulas

• 3H2O has 6 hydrogens and 3 oxygens
• 2NH3 has 2 nitrogen and 6 hydrogens
• 4CH4 has ?
• 3CO2 has ?
• 2AgNO3 has ?

4 carbon and 16 hydrogen
3 carbon and 6 oxygen
2 Ag, 2 N, 6 O
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HI
CH4
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(No Transcript)
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Lets Try one more

• 2Al(NO3)3

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Hydrates

• group of salts that have water molecules stuffed
  in their empty spaces
• Ex CuSO4?5H2O
• ? means is associated with or included
• DOES NOT refer to multiplication
• Not a true chemical bond
• structure is definite so
• empty spaces is definite
• water molecules is definite

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CuSO4?5H2O

• Count up the atoms!

Cu x 1 S x 1 O x 4 H x 10 O x 5 total 21
atoms
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5CuSO4?5H2O

• Count up the atoms!

Cu x 5 S x 5 O x 20 (5x4) H x 50 (5x5x2) O X 25
(5x5) total 105 atoms
Coefficients x Subscripts