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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 6 protons and 5 neutrons. What is its mass number?

    6 p⁺ · 5 n⁰ · A = Z + N = ?

  2. 2. An atom has 12 protons and 15 neutrons. What is its mass number?

    12 p⁺ · 15 n⁰ · A = Z + N = ?

  3. 3. An atom has 17 protons and 26 neutrons. What is its mass number?

    17 p⁺ · 26 n⁰ · A = Z + N = ?

  4. 4. An atom has 15 protons and 17 neutrons. What is its mass number?

    15 p⁺ · 17 n⁰ · A = Z + N = ?

  5. 5. An atom has 18 protons and 28 neutrons. What is its mass number?

    18 p⁺ · 28 n⁰ · A = Z + N = ?

  6. 6. An atom has 7 protons and 23 neutrons. What is its mass number?

    7 p⁺ · 23 n⁰ · A = Z + N = ?

  7. 7. An atom has 19 protons and 26 neutrons. What is its mass number?

    19 p⁺ · 26 n⁰ · A = Z + N = ?

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

    9 p⁺ · 8 n⁰ · A = Z + N = ?

  9. 9. An atom has 14 protons and 13 neutrons. What is its mass number?

    14 p⁺ · 13 n⁰ · A = Z + N = ?

  10. 10. An atom has 8 protons and 20 neutrons. What is its mass number?

    8 p⁺ · 20 n⁰ · A = Z + N = ?

  11. 11. An atom has 7 protons and 29 neutrons. What is its mass number?

    7 p⁺ · 29 n⁰ · A = Z + N = ?

  12. 12. An atom has 10 protons and 3 neutrons. What is its mass number?

    10 p⁺ · 3 n⁰ · A = Z + N = ?
12 questions · Seed 55 · 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 6 protons and 5 neutrons. What is its mass number?

    11

    Mass number counts protons and neutrons: 6 + 5 = 11.

  2. 2. An atom has 12 protons and 15 neutrons. What is its mass number?

    27

    Mass number counts protons and neutrons: 12 + 15 = 27.

  3. 3. An atom has 17 protons and 26 neutrons. What is its mass number?

    43

    Mass number counts protons and neutrons: 17 + 26 = 43.

  4. 4. An atom has 15 protons and 17 neutrons. What is its mass number?

    32

    Mass number counts protons and neutrons: 15 + 17 = 32.

  5. 5. An atom has 18 protons and 28 neutrons. What is its mass number?

    46

    Mass number counts protons and neutrons: 18 + 28 = 46.

  6. 6. An atom has 7 protons and 23 neutrons. What is its mass number?

    30

    Mass number counts protons and neutrons: 7 + 23 = 30.

  7. 7. An atom has 19 protons and 26 neutrons. What is its mass number?

    45

    Mass number counts protons and neutrons: 19 + 26 = 45.

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

    17

    Mass number counts protons and neutrons: 9 + 8 = 17.

  9. 9. An atom has 14 protons and 13 neutrons. What is its mass number?

    27

    Mass number counts protons and neutrons: 14 + 13 = 27.

  10. 10. An atom has 8 protons and 20 neutrons. What is its mass number?

    28

    Mass number counts protons and neutrons: 8 + 20 = 28.

  11. 11. An atom has 7 protons and 29 neutrons. What is its mass number?

    36

    Mass number counts protons and neutrons: 7 + 29 = 36.

  12. 12. An atom has 10 protons and 3 neutrons. What is its mass number?

    13

    Mass number counts protons and neutrons: 10 + 3 = 13.

12 questions · Seed 55 · 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 6 protons and 5 neutrons. What is its mass number?

    6 p⁺ · 5 n⁰ · A = Z + N = ?

  2. 2. An atom has 12 protons and 15 neutrons. What is its mass number?

    12 p⁺ · 15 n⁰ · A = Z + N = ?

  3. 3. An atom has 17 protons and 26 neutrons. What is its mass number?

    17 p⁺ · 26 n⁰ · A = Z + N = ?

  4. 4. An atom has 15 protons and 17 neutrons. What is its mass number?

    15 p⁺ · 17 n⁰ · A = Z + N = ?

  5. 5. An atom has 18 protons and 28 neutrons. What is its mass number?

    18 p⁺ · 28 n⁰ · A = Z + N = ?

  6. 6. An atom has 7 protons and 23 neutrons. What is its mass number?

    7 p⁺ · 23 n⁰ · A = Z + N = ?

  7. 7. An atom has 19 protons and 26 neutrons. What is its mass number?

    19 p⁺ · 26 n⁰ · A = Z + N = ?

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

    9 p⁺ · 8 n⁰ · A = Z + N = ?

  9. 9. An atom has 14 protons and 13 neutrons. What is its mass number?

    14 p⁺ · 13 n⁰ · A = Z + N = ?

  10. 10. An atom has 8 protons and 20 neutrons. What is its mass number?

    8 p⁺ · 20 n⁰ · A = Z + N = ?

  11. 11. An atom has 7 protons and 29 neutrons. What is its mass number?

    7 p⁺ · 29 n⁰ · A = Z + N = ?

  12. 12. An atom has 10 protons and 3 neutrons. What is its mass number?

    10 p⁺ · 3 n⁰ · A = Z + N = ?
12 questions · Seed 55 · 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 6 protons and 5 neutrons. What is its mass number?

    11

    Mass number counts protons and neutrons: 6 + 5 = 11.

  2. 2. An atom has 12 protons and 15 neutrons. What is its mass number?

    27

    Mass number counts protons and neutrons: 12 + 15 = 27.

  3. 3. An atom has 17 protons and 26 neutrons. What is its mass number?

    43

    Mass number counts protons and neutrons: 17 + 26 = 43.

  4. 4. An atom has 15 protons and 17 neutrons. What is its mass number?

    32

    Mass number counts protons and neutrons: 15 + 17 = 32.

  5. 5. An atom has 18 protons and 28 neutrons. What is its mass number?

    46

    Mass number counts protons and neutrons: 18 + 28 = 46.

  6. 6. An atom has 7 protons and 23 neutrons. What is its mass number?

    30

    Mass number counts protons and neutrons: 7 + 23 = 30.

  7. 7. An atom has 19 protons and 26 neutrons. What is its mass number?

    45

    Mass number counts protons and neutrons: 19 + 26 = 45.

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

    17

    Mass number counts protons and neutrons: 9 + 8 = 17.

  9. 9. An atom has 14 protons and 13 neutrons. What is its mass number?

    27

    Mass number counts protons and neutrons: 14 + 13 = 27.

  10. 10. An atom has 8 protons and 20 neutrons. What is its mass number?

    28

    Mass number counts protons and neutrons: 8 + 20 = 28.

  11. 11. An atom has 7 protons and 29 neutrons. What is its mass number?

    36

    Mass number counts protons and neutrons: 7 + 29 = 36.

  12. 12. An atom has 10 protons and 3 neutrons. What is its mass number?

    13

    Mass number counts protons and neutrons: 10 + 3 = 13.

12 questions · Seed 55 · Age guidance, not curriculum certification