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Grade 8 Atomic Structure & Isotopes Worksheet with Answers

Grade 8 (US) · Year 9 (UK) · Class 8 (India) · Science

Unit 6: Going FurtherAdvanced: High School PreviewNGSS HS-PS1-1Advanced

Finding protons, neutrons and electrons from atomic number, mass number and charge. This free middle school worksheet has 16 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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Atomic Structure & Isotopes

Grade 8 · Science

Score___ / 16

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Class

Date

Learning goal: Advanced: High School Preview · NGSS HS-PS1-1

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

Example

How many electrons does a neutral atom of beryllium (atomic number 4) have?

Answer: 4

Part A

Label the diagram. Use the words in the box.

Word bank

protonnucleusneutronelectron
+++−−−−−−−−1234
  1. 1
  2. 2
  3. 3
  4. 4
Part B

Answer each question. Use full sentences where you can.

  1. 5

    Nitrogen-14 has atomic number 7. How many neutrons does it have?

  2. 6

    Potassium-39 has atomic number 19. How many neutrons does it have?

  3. 7

    Fluorine-19 has atomic number 9. How many neutrons does it have?

  4. 8

    Argon-40 has atomic number 18. How many neutrons does it have?

  5. 9

    How many protons does an atom of calcium (Ca, atomic number 20) have?

  6. 10

    Magnesium-24 has atomic number 12. How many neutrons does it have?

  7. 11

    How many protons does an atom of aluminum (Al, atomic number 13) have?

  8. 12

    How many protons does an atom of sulfur (S, atomic number 16) have?

  9. 13

    Sulfur-32 has atomic number 16. How many neutrons does it have?

  10. 14

    Phosphorus-31 has atomic number 15. How many neutrons does it have?

  11. 15

    An isotope of oxygen (atomic number 8) has a mass number of 19. How many protons and neutrons does it have?

  12. 16

    How many protons does an atom of oxygen (O, atomic number 8) have?

★ Challenge corner for fast finishers

Why do you see lightning before you hear thunder?

How did I do?

Teacher's comments

Free printable worksheets with answer keys · aethelsystems.com/worksheets/science/8/atomic_structure

Answer key (click to show)
  1. 1.nucleus
  2. 2.proton
  3. 3.neutron
  4. 4.electron
  5. 5.7
  6. 6.20
  7. 7.10
  8. 8.22
  9. 9.20
  10. 10.12
  11. 11.13
  12. 12.16
  13. 13.16
  14. 14.16
  15. 15.8 protons, 11 neutrons
  16. 16.8
  17. ★light travels much faster than sound (challenge corner)

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