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8th grade Read a chemical formula and its ball-and-stick model worksheet

6 printable versionsBuilding Confidence10 questions · answer keyFree · no account

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Read a chemical formula and its ball-and-stick model

Grade 8 Science Worksheet - Building Confidence

NameDate

Circle the best answer.

  1. Ari labels a water drop drawing with its formula, H₂O. How many oxygen atoms are in one water molecule?

    • 0 oxygen atoms
    • 3 oxygen atoms
    • 1 oxygen atom
    • 2 oxygen atoms

  2. Bo blows up a balloon, and the breath inside holds some carbon dioxide, CO₂. How many carbon atoms are in one CO₂ molecule?

    • 1 carbon atom
    • 3 carbon atoms
    • 2 carbon atoms
    • 0 carbon atoms

  3. Kira draws an ammonia model: 1 N ball joined by 3 sticks to 3 H balls. It looks a bit like a tiny tripod. How many atoms does it show?

    • 2 atoms
    • 4 atoms
    • 6 atoms
    • 3 atoms

  4. Luz looks at a hydrogen peroxide model: H–O–O–H, with 3 sticks joining 4 balls in a zigzag. How many atoms does the model show?

    • 2 atoms
    • 7 atoms
    • 3 atoms
    • 4 atoms

  5. Symbol and name. N nitrogen; Na sodium; Ne neon; Cl chlorine. Milo reads that table salt is NaCl. Which element does the symbol Na stand for?

    • Neon
    • Sodium
    • Two elements, N and a
    • Nitrogen

  6. Symbol and name. C carbon; Ca calcium; Co cobalt; O oxygen. Noah finds a seashell on the beach. Shells are mostly CaCO₃. Which element does the symbol Ca stand for?

    • Carbon
    • Calcium
    • Cobalt
    • Two elements, C and a

  7. Symbol and name. C carbon; Co cobalt; O oxygen. Pia compares two formulas on a card: Co and CO. Which one shows atoms of two different elements?

    • Co: carbon and o
    • Neither one
    • Both show the same two elements
    • CO: carbon and oxygen

  8. The gas that heats Ren's cooking pot is mostly methane, CH₄. What does one CH₄ molecule hold?

    • 4 hydrogen atoms and no carbon atom
    • 2 atoms: 1 carbon, 1 hydrogen
    • 4 carbon atoms and 1 hydrogen atom
    • 1 carbon atom and 4 hydrogen atoms

  9. Tala fills a party balloon with air from a pump. Air is mostly nitrogen, N₂. What does one N₂ molecule hold?

    • 1 nitrogen atom
    • 3 nitrogen atoms
    • 4 nitrogen atoms
    • 2 nitrogen atoms

  10. Zee reads the label H₂O on a science poster. What does one water molecule hold?

    • 2 hydrogen atoms and 1 oxygen atom
    • 1 hydrogen atom and 2 oxygen atoms
    • 2 atoms: 1 hydrogen, 1 oxygen
    • 2 hydrogen atoms and no oxygen
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8th grade Read a chemical formula and its ball-and-stick model worksheet – printable
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About this worksheet

Chemical formulas and ball-and-stick models. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can read a formula: each small number (subscript) counts the atoms of the symbol just before it, and no number means one atom.
  • I can match a formula to a ball-and-stick model and write the formula from a model.
  • I can count all the atoms in one or more molecules, using a big number in front (coefficient) when there is one.

Standard: MS-PS1-1

Words to know

chemical formula: Symbols and small numbers that show the atoms in a substance

symbol: One or two letters for an element; the first is always a capital

subscript: The small low number after a symbol: how many of that atom

molecule: A group of atoms joined together

ball-and-stick model: A drawing where balls are atoms and sticks are the bonds joining them

bond: The link that holds two atoms together, drawn as a stick

coefficient: A big number in front of a formula: how many molecules

Common mistakes

Your child treated a symbol with no small number as zero atoms. In H₂O, point to the O together: no number means one atom.

Your child gave a small number to the wrong element. In CO₂, the 2 belongs to the O just before it, so there are two oxygens and one carbon.

Your child counted the kinds of atoms instead of all the atoms. Count the balls of a model together, one ball at a time.

Questions parents ask

What is the most common mistake with read a chemical formula and its ball-and-stick model?

Your child treated a symbol with no small number as zero atoms. In H₂O, point to the O together: no number means one atom.

Are these 8th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

More grade 8 science

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