Chemical Formulas

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Chemical Formulas
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Chemical Formulas
-We use chemical symbols to abbreviate an
elements name. EX. (Rules first letter is
always_______________. If it has a second
letter it is always _________________.) -When
one or more atoms of different elements bond
together they form a __________________. -To
abbreviate the name of a compound we write a
____________________.
H, Fe, Ca, Hg, Au, Ag, K, Cs, Hf
capitalized
lower case
compound
O
H
H
chemical formula
3
orbital

H
H
O
H
O
1 atom of ____ 1 atom of ____ 1 atom of
_____ 1 molecule of_________ -This
combination of atoms makes a compound called
_________ or _______
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water
H
O
2
4
H2O
If there is no number it is understood to be
________.
1
one
The H comes before the O, just like it
does going left to right on the periodic table
This number is called a __________ It only
applies to the letter to the ________.
subscript
left
Other examples CO2 _______________ H2O2
________________ C12H22O11___________
NaCl ________________
Carbon Dioxide
Hydrogen Peroxide
Sugar
Sodium Chloride
-Prefixes (like di- or pre-) or suffixes
(like ide or ate) can be added to the formula
name (usually the second element) This is done so
that it is understood that you are talking about
a compound and not just listing elements.
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What if I you have two molecules of water? How do
you write that?
2 H2O


This number is called a ___________ It tells you
the number of molecules of the compound are
present.
coefficient
-If there is no coefficient, it is understood to
be a 1.
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-Sample problems
Sulfur
1
Oxygen
11
3
Lead
Chlorine
8
Carbon
9
Aluminum
8
Silver
10
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Why isnt Ba(OH)2 just written as BaO2H2?
(OH)2
O2H2
means
means
Oxygen


Oxygen
Oxygen
Barium

Barium
Hydrogen
Hydrogen
Hydrogen
Oxygen
Hydrogen
-The way its written tells you the history of
how the Molecule was formed.
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-Sample problems
Sulfur
1
Oxygen
11
3
Lead
Chlorine
8
Carbon
9
Aluminum
8
Silver
10
6
Hydrogen
Oxygen
18