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ScienceAges 13-15

Protons, neutrons & mass number

Calculate an atom’s mass number from its proton and neutron counts. This is not relative atomic mass. Review suitability for your learners before teaching.

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Age band:Ages 13-15Ages 16-18

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Worksheet StudioPractice pack · Ages 13-15

Protons, neutrons & mass number

Take your time. Show your thinking.

  1. 1. An atom has 5 protons and 7 neutrons. What is its mass number?

    5 p⁺ · 7 n⁰ · A = Z + N = ?

  2. 2. An atom has 5 protons and 19 neutrons. What is its mass number?

    5 p⁺ · 19 n⁰ · A = Z + N = ?

  3. 3. An atom has 9 protons and 5 neutrons. What is its mass number?

    9 p⁺ · 5 n⁰ · A = Z + N = ?

  4. 4. An atom has 17 protons and 10 neutrons. What is its mass number?

    17 p⁺ · 10 n⁰ · A = Z + N = ?

  5. 5. An atom has 9 protons and 25 neutrons. What is its mass number?

    9 p⁺ · 25 n⁰ · A = Z + N = ?

  6. 6. An atom has 11 protons and 24 neutrons. What is its mass number?

    11 p⁺ · 24 n⁰ · A = Z + N = ?

  7. 7. An atom has 17 protons and 9 neutrons. What is its mass number?

    17 p⁺ · 9 n⁰ · A = Z + N = ?

  8. 8. An atom has 11 protons and 10 neutrons. What is its mass number?

    11 p⁺ · 10 n⁰ · A = Z + N = ?

  9. 9. An atom has 8 protons and 18 neutrons. What is its mass number?

    8 p⁺ · 18 n⁰ · A = Z + N = ?

  10. 10. An atom has 6 protons and 13 neutrons. What is its mass number?

    6 p⁺ · 13 n⁰ · A = Z + N = ?

  11. 11. An atom has 9 protons and 23 neutrons. What is its mass number?

    9 p⁺ · 23 n⁰ · A = Z + N = ?

  12. 12. An atom has 14 protons and 27 neutrons. What is its mass number?

    14 p⁺ · 27 n⁰ · A = Z + N = ?
12 questions · Seed 49 · Age guidance, not curriculum certification
View the answer key
Worksheet StudioAnswer key · Ages 13-15

Protons, neutrons & mass number

Answers and reasoning. Review before teaching.

  1. 1. An atom has 5 protons and 7 neutrons. What is its mass number?

    12

    Mass number counts protons and neutrons: 5 + 7 = 12.

  2. 2. An atom has 5 protons and 19 neutrons. What is its mass number?

    24

    Mass number counts protons and neutrons: 5 + 19 = 24.

  3. 3. An atom has 9 protons and 5 neutrons. What is its mass number?

    14

    Mass number counts protons and neutrons: 9 + 5 = 14.

  4. 4. An atom has 17 protons and 10 neutrons. What is its mass number?

    27

    Mass number counts protons and neutrons: 17 + 10 = 27.

  5. 5. An atom has 9 protons and 25 neutrons. What is its mass number?

    34

    Mass number counts protons and neutrons: 9 + 25 = 34.

  6. 6. An atom has 11 protons and 24 neutrons. What is its mass number?

    35

    Mass number counts protons and neutrons: 11 + 24 = 35.

  7. 7. An atom has 17 protons and 9 neutrons. What is its mass number?

    26

    Mass number counts protons and neutrons: 17 + 9 = 26.

  8. 8. An atom has 11 protons and 10 neutrons. What is its mass number?

    21

    Mass number counts protons and neutrons: 11 + 10 = 21.

  9. 9. An atom has 8 protons and 18 neutrons. What is its mass number?

    26

    Mass number counts protons and neutrons: 8 + 18 = 26.

  10. 10. An atom has 6 protons and 13 neutrons. What is its mass number?

    19

    Mass number counts protons and neutrons: 6 + 13 = 19.

  11. 11. An atom has 9 protons and 23 neutrons. What is its mass number?

    32

    Mass number counts protons and neutrons: 9 + 23 = 32.

  12. 12. An atom has 14 protons and 27 neutrons. What is its mass number?

    41

    Mass number counts protons and neutrons: 14 + 27 = 41.

12 questions · Seed 49 · Age guidance, not curriculum certification
Worksheet StudioPractice pack · Ages 13-15

Protons, neutrons & mass number

Take your time. Show your thinking.

  1. 1. An atom has 5 protons and 7 neutrons. What is its mass number?

    5 p⁺ · 7 n⁰ · A = Z + N = ?

  2. 2. An atom has 5 protons and 19 neutrons. What is its mass number?

    5 p⁺ · 19 n⁰ · A = Z + N = ?

  3. 3. An atom has 9 protons and 5 neutrons. What is its mass number?

    9 p⁺ · 5 n⁰ · A = Z + N = ?

  4. 4. An atom has 17 protons and 10 neutrons. What is its mass number?

    17 p⁺ · 10 n⁰ · A = Z + N = ?

  5. 5. An atom has 9 protons and 25 neutrons. What is its mass number?

    9 p⁺ · 25 n⁰ · A = Z + N = ?

  6. 6. An atom has 11 protons and 24 neutrons. What is its mass number?

    11 p⁺ · 24 n⁰ · A = Z + N = ?

  7. 7. An atom has 17 protons and 9 neutrons. What is its mass number?

    17 p⁺ · 9 n⁰ · A = Z + N = ?

  8. 8. An atom has 11 protons and 10 neutrons. What is its mass number?

    11 p⁺ · 10 n⁰ · A = Z + N = ?

  9. 9. An atom has 8 protons and 18 neutrons. What is its mass number?

    8 p⁺ · 18 n⁰ · A = Z + N = ?

  10. 10. An atom has 6 protons and 13 neutrons. What is its mass number?

    6 p⁺ · 13 n⁰ · A = Z + N = ?

  11. 11. An atom has 9 protons and 23 neutrons. What is its mass number?

    9 p⁺ · 23 n⁰ · A = Z + N = ?

  12. 12. An atom has 14 protons and 27 neutrons. What is its mass number?

    14 p⁺ · 27 n⁰ · A = Z + N = ?
12 questions · Seed 49 · Age guidance, not curriculum certification
Worksheet StudioAnswer key · Ages 13-15

Protons, neutrons & mass number

Answers and reasoning. Review before teaching.

  1. 1. An atom has 5 protons and 7 neutrons. What is its mass number?

    12

    Mass number counts protons and neutrons: 5 + 7 = 12.

  2. 2. An atom has 5 protons and 19 neutrons. What is its mass number?

    24

    Mass number counts protons and neutrons: 5 + 19 = 24.

  3. 3. An atom has 9 protons and 5 neutrons. What is its mass number?

    14

    Mass number counts protons and neutrons: 9 + 5 = 14.

  4. 4. An atom has 17 protons and 10 neutrons. What is its mass number?

    27

    Mass number counts protons and neutrons: 17 + 10 = 27.

  5. 5. An atom has 9 protons and 25 neutrons. What is its mass number?

    34

    Mass number counts protons and neutrons: 9 + 25 = 34.

  6. 6. An atom has 11 protons and 24 neutrons. What is its mass number?

    35

    Mass number counts protons and neutrons: 11 + 24 = 35.

  7. 7. An atom has 17 protons and 9 neutrons. What is its mass number?

    26

    Mass number counts protons and neutrons: 17 + 9 = 26.

  8. 8. An atom has 11 protons and 10 neutrons. What is its mass number?

    21

    Mass number counts protons and neutrons: 11 + 10 = 21.

  9. 9. An atom has 8 protons and 18 neutrons. What is its mass number?

    26

    Mass number counts protons and neutrons: 8 + 18 = 26.

  10. 10. An atom has 6 protons and 13 neutrons. What is its mass number?

    19

    Mass number counts protons and neutrons: 6 + 13 = 19.

  11. 11. An atom has 9 protons and 23 neutrons. What is its mass number?

    32

    Mass number counts protons and neutrons: 9 + 23 = 32.

  12. 12. An atom has 14 protons and 27 neutrons. What is its mass number?

    41

    Mass number counts protons and neutrons: 14 + 27 = 41.

12 questions · Seed 49 · Age guidance, not curriculum certification