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Grade 9 Atomic Structure & Isotopes Worksheet with Answers

Grade 9 (US) · Year 10 (UK) · Class 9 (India) · Chemistry

Unit 2: Atoms & the Periodic TableAtoms & ElementsNGSS HS-PS1-1

Finding protons, neutrons and electrons from atomic number, mass number and charge. This free high 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 9 · Chemistry

Score___ / 16

Name

Class

Date

Learning goal: Atoms & Elements · 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 silicon (atomic number 14) have?

Answer: 14

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

    How many protons does an atom of carbon (C, atomic number 6) have?

  2. 6

    An isotope of argon (atomic number 18) has a mass number of 41. How many protons and neutrons does it have?

  3. 7

    How many protons does an atom of silicon (Si, atomic number 14) have?

  4. 8

    An isotope of potassium (atomic number 19) has a mass number of 40. How many protons and neutrons does it have?

  5. 9

    How many protons does an atom of magnesium (Mg, atomic number 12) have?

  6. 10

    An isotope of magnesium (atomic number 12) has a mass number of 27. How many protons and neutrons does it have?

  7. 11

    An isotope of silicon (atomic number 14) has a mass number of 30. How many protons and neutrons does it have?

  8. 12

    Beryllium-9 has atomic number 4. How many neutrons does it have?

  9. 13

    How many protons does an atom of boron (B, atomic number 5) have?

  10. 14

    An isotope of beryllium (atomic number 4) has a mass number of 11. How many protons and neutrons does it have?

  11. 15

    An isotope of carbon (atomic number 6) has a mass number of 14. How many protons and neutrons does it have?

  12. 16

    How many protons does an atom of beryllium (Be, atomic number 4) 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/chemistry/9/atomic_structure

Answer key (click to show)
  1. 1.nucleus
  2. 2.proton
  3. 3.neutron
  4. 4.electron
  5. 5.6
  6. 6.18 protons, 23 neutrons
  7. 7.14
  8. 8.19 protons, 21 neutrons
  9. 9.12
  10. 10.12 protons, 15 neutrons
  11. 11.14 protons, 16 neutrons
  12. 12.5
  13. 13.5
  14. 14.4 protons, 7 neutrons
  15. 15.6 protons, 8 neutrons
  16. 16.4
  17. ★light travels much faster than sound (challenge corner)

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