RULES FOR COUNTING ATOMS

#Counting_Atoms
#SUBSCRIPT
#COEFFICIENT
#chemical_formula

HOW TO COUNT ATOMS
HOW TO COUNT ATOMS IN A CHEMICAL FORMULA
(5 Easy Steps)
Step 1: Write the chemical formula
Step 2: List all the atoms
Step 3: Count the number of atoms of each element in 1 molecule.
Step 4: Multiply the number of atoms of each by the coefficient.
Step 5: Make sure your answer makes sense.
Background Information:
• subscripts – the little numbers that tell how many atoms there are
(ex: In 3H2O, the 2 is the subscript)
• coefficients – regular-sized numbers that tell how many molecules there
are (ex: In 3H2O, the 3 is the coefficient)
Example: 3H2O
• The subscript 2 in the example above comes after the H.
This means there are two H’s (hydrogen atoms) in each molecule.
• The coefficient 3 shows that there are three of the H2O molecules.
We could draw each molecule to help show us how many atoms are present.
Now we can count the number of H’s and the number of O’s.
3H2O has 6 hydrogen atoms and 3 oxygen atoms.
However, drawing out each equation is NOT PRACTICAL. The number of atoms
can be counted without having to draw it out.