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Counting Atoms in Chemical Formulas

A Grade 12 chemistry worksheet to practice counting atoms in various chemical formulas, including those with parentheses and coefficients.

Grade 12 Science ChemistryCounting Atoms in Chemical Formulas
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Standards

HS-PS1-1HS-PS1-7

Topics

chemistryatomschemical formulasstoichiometrygrade 12
9 sections · Free to use · Printable
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Counting Atoms in Chemical Formulas

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Carefully analyze each chemical formula and determine the total number of atoms for each element present. Pay close attention to subscripts, parentheses, and coefficients.

1. In H₂O, there are   hydrogen atoms and   oxygen atoms.

2. In CO₂, there is   carbon atom and   oxygen atoms.

3. In NaCl, there is   sodium atom and   chlorine atom.

4. In C₆H₁₂O₆, there are   carbon atoms,   hydrogen atoms, and   oxygen atoms.

5. How many oxygen atoms are in Mg(OH)₂?

a

1

b

2

c

3

d

4

6. How many total atoms are in (NH₄)₃PO₄?

a

18

b

20

c

21

d

23

7. For the compound 2H₂SO₄, list the number of atoms for each element.

8. How many total oxygen atoms are present in 3Ca(NO₃)₂?

9. In the formula 4Fe₂(SO₄)₃, there are 12 sulfur atoms.

T

True

F

False

10. The coefficient in a chemical formula multiplies all atoms in the entire formula.

T

True

F

False

11. Consider the compound 2K₃[Fe(CN)₆]. Determine the total number of potassium, iron, carbon, and nitrogen atoms.