COUNT ATOM How to count atoms. 2H 2 O COEFFICIENT SUBSCRIPT.
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Transcript of COUNT ATOM How to count atoms. 2H 2 O COEFFICIENT SUBSCRIPT.
COUNT ATOMHow to count atoms
2H2OCOEFFICIENT SUBSCRIPT
2H2OThe coefficient gets applied to the
ENTIRE formula
-this means that there are 2 molecules of water present!
-you MULTIPLY this number by every subscript in the formula
2H2O
2MOLECULES!!!!
2H2OThe subscript only gets applied to the
element it follows
-If there is no subscript present, it is assumed that there is only 1 atom of
that element in the molecule.
2H2OHow many hydrogen atoms are present?
4
How many oxygen atoms are present?
2
The easiest way to count atoms:
1. Write down all of the symbols for all of the elements present in the formula
2. If there is a coefficient, write this number next to each of the symbols
3. Multiply the coefficient by the subscripts of each of the elements present in the formula
Let’s try an example:
4CaCO3
4CaCO3
1. Write down symbols
4CaCO3
Ca
C
O
Write down the coefficient next to each symbol
4CaCO3
Ca
C
O
4
4
4
Multiply by the subscript
4CaCO3
Ca
C
O
4
4
4
X
X
X
1
1
3
Multiply…
4CaCO3
Ca
C
O
4
4
4
X
X
X
1
1
3
=
=
=
4
4
12
Add totals together to get the total amount of atoms
4CaCO3
Ca
C
O
4
4
4
X
X
X
1
1
3
=
=
=
4
4
12
20 atoms
3CO2
3CO2
2C6H12O6
GLUCOSE
2C6H12O6
6K2SO4
6K2SO4
CaMg(CO3)2
CaMg(CO3)2
3Pb(NO3)2
3Pb(NO3)2