Together At Last: Writing Chemical Formulas!
Each of these groupings shows the atoms that create compounds. Write the formula that
shows the makeup of the compound.
_____________ 1. hydrogen chloride
_____________ 2. ammonia
H
H
N
H
Cl
H
_____________ 3. dihydrogen monoxide
H
O
H
_____________ 5. carbon dioxide
O
C
O
_____________ 4. hydrogen peroxide
H
O
O
H
_____________ 6. sand (silicon dioxide)
O
Si
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TEKS 8.5 (D) Chemical Formulas
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O
____________ 7. diphosphorous pentoxide
O
O
______________ 8. chalk (calcium carbonate)
O
O
P
Ca
O
P
O
O
O
__________ 9. baking soda (sodium bicarbonate)
______________ 10. methane
O
H
Na
C
C
Cl
H
H
O
_____________ 11. salt (sodium chloride)
H
H
O
Na
C
______________ 12. carbon monoxide
C
O
Sometimes, you want to represent more than one of the same kind of molecule. To do this, you add a big number
in front, called a coefficient. No coefficient is needed when there’s only one molecule.
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TEKS 8.5 (D) Chemical Formulas
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H
H
O
H
H
H
O
H
O
3H2O
_____________ 13. hydrogen gas
H
_____________ 14. carbon monoxide
H
H
H
H
H
H
C
H
O
C
H
O
C
H
_________ 15. silver nitrate
_________ 16. oxygen
O
O
N
O
Ag
O
O
O
N
O
Ag
O
Discussion Questions:
1. What do the numbers to the right of the chemical symbols represent?
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TEKS 8.5 (D) Chemical Formulas
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O
2. What is the name of the number found to the right of the chemical symbols?
3. How is a single atom of an element represented in written form? Given an example and
describe.
4. If an elements chemical symbol is composed of more than one letter, how is it written?
Give an example and describe.
5. Describe what the numbers to the left of the chemical symbols tell about a compound.
6. What is the name of the number to the left of chemical symbols?
7. Write a chemical formula that shows four molecules of hydrochloric acid (HCl)?
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TEKS 8.5 (D) Chemical Formulas
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