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COUNTING ATOMS: Notes & Practice
Law of Conservation of Mass:
When you count atoms in a chemical formula or a chemical equation, you
will deal with two types of numbers: coefficients and subscripts.
Coefficients are BEFORE the element & they are multipliers. For example –
There are 4 Hydrogen atoms on the reactant side of the example equation
because 2 X 2 = 4. Subscripts go with the element they are BEHIND. For
example – The 2 behind the Oxygen on the reactant side means there are 2
Oxygen atoms. Now you try
– How many Hydrogens on the product side? ______
_ How many Oxygens on the product side? ________
Counting Atoms Sheet
Write the number of atoms with the name of the element. For example, H 2O has
2 Hydrogen atoms and one Oxygen atom.
1)
CaF2 ______________________________________________________
2)
Be(OH)2 ____________________________________________________
3)
NO2 ______________________________________________________
4)
Al2(SO4)3 ___________________________________________________
5)
NH4NO3 ____________________________________________________
6)
S2F2 ______________________________________________________
7)
Na2CO3 ____________________________________________________
8)
CH4 ______________________________________________________