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Grade 10 Compounds & Molecules Worksheet with Answers

Grade 10 (US) · Year 11 (UK) · Class 10 (India) · Chemistry

Unit 2: Bonding & CompoundsCompoundsNGSS HS-PS1-2

How elements combine into compounds and molecules, and reading chemical formulas. This free high school worksheet has 12 questions and a full answer key. Print it or save it as a PDF — every answer is checked by code, not guessed.

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Compounds & Molecules

Grade 10 · Chemistry

Score___ / 12

Name

Class

Date

Learning goal: Compounds · NGSS HS-PS1-2

Directions: This worksheet has 2 parts. Read the instructions at the start of each part.

Example

What is the chemical formula for water?

Answer: H₂O

RememberAtoms, elements and compounds

H₂O2 hydrogen atoms (the small 2)1 oxygen atom (no number = 1)Atomsmallest pieceElementone kind of atom: OMoleculeatoms bonded: O₂Compounddifferent elements: CO₂Mixturenot bonded: salt water
Part A

Match each clue to the right word. Write the letter in the box.

  1. 1What type of bond forms when electrons are transferred, as in NaCl?
  2. 2What do we call two or more atoms bonded together?
  3. 3What do we call a combination of substances that are not chemically bonded, like salt water?
  4. 4What type of bond forms when atoms share electrons?
  5. 5What is the chemical formula for methane?
  6. 6What is the chemical formula for oxygen gas?
  • AMolecule
  • BMixture
  • CO₂
  • DIonic bond
  • ECovalent bond
  • FCH₄
Part B

Answer each question. Use full sentences where you can.

  1. 7

    How many atoms of each element are in one molecule of CO₂?

  2. 8

    How many atoms are in one molecule of H₂O?

  3. 9

    Why is water (H₂O) a compound but oxygen gas (O₂) is not?

  4. 10

    What do we call a substance made of two or more elements chemically bonded?

  5. 11

    What is the chemical formula for table salt?

  6. 12

    What is a substance made of only one type of atom called?

★ Challenge corner for fast finishers

Why does your breath make fog on a cold window?

How did I do?

Teacher's comments

Free printable worksheets with answer keys · aethelsystems.com/worksheets/chemistry/10/chemistry_compounds

Answer key (click to show)
  1. 1.D — an ionic bond
  2. 2.A — a molecule
  3. 3.B — a mixture
  4. 4.E — a covalent bond
  5. 5.F — CH₄
  6. 6.C — O₂
  7. 7.1 carbon and 2 oxygen
  8. 8.3 (2 hydrogen, 1 oxygen)
  9. 9.water contains two different elements bonded together; O₂ contains only oxygen
  10. 10.a compound
  11. 11.NaCl
  12. 12.an element
  13. ★water vapor in your breath condenses on the cold glass (challenge corner)

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