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ScienceAges 16-18

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 16-18

Protons, neutrons & mass number

Take your time. Show your thinking.

  1. 1. An atom has 15 protons and 18 neutrons. What is its mass number?

    15 p⁺ · 18 n⁰ · A = Z + N = ?

  2. 2. An atom has 2 protons and 6 neutrons. What is its mass number?

    2 p⁺ · 6 n⁰ · A = Z + N = ?

  3. 3. An atom has 2 protons and 26 neutrons. What is its mass number?

    2 p⁺ · 26 n⁰ · A = Z + N = ?

  4. 4. An atom has 12 protons and 13 neutrons. What is its mass number?

    12 p⁺ · 13 n⁰ · A = Z + N = ?

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

    13 p⁺ · 14 n⁰ · A = Z + N = ?

  6. 6. An atom has 1 protons and 3 neutrons. What is its mass number?

    1 p⁺ · 3 n⁰ · A = Z + N = ?

  7. 7. An atom has 17 protons and 28 neutrons. What is its mass number?

    17 p⁺ · 28 n⁰ · A = Z + N = ?

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

    9 p⁺ · 17 n⁰ · A = Z + N = ?

  9. 9. An atom has 5 protons and 24 neutrons. What is its mass number?

    5 p⁺ · 24 n⁰ · A = Z + N = ?

  10. 10. An atom has 20 protons and 25 neutrons. What is its mass number?

    20 p⁺ · 25 n⁰ · A = Z + N = ?

  11. 11. An atom has 18 protons and 24 neutrons. What is its mass number?

    18 p⁺ · 24 n⁰ · A = Z + N = ?

  12. 12. An atom has 14 protons and 19 neutrons. What is its mass number?

    14 p⁺ · 19 n⁰ · A = Z + N = ?
12 questions · Seed 53 · Age guidance, not curriculum certification
View the answer key
Worksheet StudioAnswer key · Ages 16-18

Protons, neutrons & mass number

Answers and reasoning. Review before teaching.

  1. 1. An atom has 15 protons and 18 neutrons. What is its mass number?

    33

    Mass number counts protons and neutrons: 15 + 18 = 33.

  2. 2. An atom has 2 protons and 6 neutrons. What is its mass number?

    8

    Mass number counts protons and neutrons: 2 + 6 = 8.

  3. 3. An atom has 2 protons and 26 neutrons. What is its mass number?

    28

    Mass number counts protons and neutrons: 2 + 26 = 28.

  4. 4. An atom has 12 protons and 13 neutrons. What is its mass number?

    25

    Mass number counts protons and neutrons: 12 + 13 = 25.

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

    27

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

  6. 6. An atom has 1 protons and 3 neutrons. What is its mass number?

    4

    Mass number counts protons and neutrons: 1 + 3 = 4.

  7. 7. An atom has 17 protons and 28 neutrons. What is its mass number?

    45

    Mass number counts protons and neutrons: 17 + 28 = 45.

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

    26

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

  9. 9. An atom has 5 protons and 24 neutrons. What is its mass number?

    29

    Mass number counts protons and neutrons: 5 + 24 = 29.

  10. 10. An atom has 20 protons and 25 neutrons. What is its mass number?

    45

    Mass number counts protons and neutrons: 20 + 25 = 45.

  11. 11. An atom has 18 protons and 24 neutrons. What is its mass number?

    42

    Mass number counts protons and neutrons: 18 + 24 = 42.

  12. 12. An atom has 14 protons and 19 neutrons. What is its mass number?

    33

    Mass number counts protons and neutrons: 14 + 19 = 33.

12 questions · Seed 53 · Age guidance, not curriculum certification
Worksheet StudioPractice pack · Ages 16-18

Protons, neutrons & mass number

Take your time. Show your thinking.

  1. 1. An atom has 15 protons and 18 neutrons. What is its mass number?

    15 p⁺ · 18 n⁰ · A = Z + N = ?

  2. 2. An atom has 2 protons and 6 neutrons. What is its mass number?

    2 p⁺ · 6 n⁰ · A = Z + N = ?

  3. 3. An atom has 2 protons and 26 neutrons. What is its mass number?

    2 p⁺ · 26 n⁰ · A = Z + N = ?

  4. 4. An atom has 12 protons and 13 neutrons. What is its mass number?

    12 p⁺ · 13 n⁰ · A = Z + N = ?

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

    13 p⁺ · 14 n⁰ · A = Z + N = ?

  6. 6. An atom has 1 protons and 3 neutrons. What is its mass number?

    1 p⁺ · 3 n⁰ · A = Z + N = ?

  7. 7. An atom has 17 protons and 28 neutrons. What is its mass number?

    17 p⁺ · 28 n⁰ · A = Z + N = ?

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

    9 p⁺ · 17 n⁰ · A = Z + N = ?

  9. 9. An atom has 5 protons and 24 neutrons. What is its mass number?

    5 p⁺ · 24 n⁰ · A = Z + N = ?

  10. 10. An atom has 20 protons and 25 neutrons. What is its mass number?

    20 p⁺ · 25 n⁰ · A = Z + N = ?

  11. 11. An atom has 18 protons and 24 neutrons. What is its mass number?

    18 p⁺ · 24 n⁰ · A = Z + N = ?

  12. 12. An atom has 14 protons and 19 neutrons. What is its mass number?

    14 p⁺ · 19 n⁰ · A = Z + N = ?
12 questions · Seed 53 · Age guidance, not curriculum certification
Worksheet StudioAnswer key · Ages 16-18

Protons, neutrons & mass number

Answers and reasoning. Review before teaching.

  1. 1. An atom has 15 protons and 18 neutrons. What is its mass number?

    33

    Mass number counts protons and neutrons: 15 + 18 = 33.

  2. 2. An atom has 2 protons and 6 neutrons. What is its mass number?

    8

    Mass number counts protons and neutrons: 2 + 6 = 8.

  3. 3. An atom has 2 protons and 26 neutrons. What is its mass number?

    28

    Mass number counts protons and neutrons: 2 + 26 = 28.

  4. 4. An atom has 12 protons and 13 neutrons. What is its mass number?

    25

    Mass number counts protons and neutrons: 12 + 13 = 25.

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

    27

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

  6. 6. An atom has 1 protons and 3 neutrons. What is its mass number?

    4

    Mass number counts protons and neutrons: 1 + 3 = 4.

  7. 7. An atom has 17 protons and 28 neutrons. What is its mass number?

    45

    Mass number counts protons and neutrons: 17 + 28 = 45.

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

    26

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

  9. 9. An atom has 5 protons and 24 neutrons. What is its mass number?

    29

    Mass number counts protons and neutrons: 5 + 24 = 29.

  10. 10. An atom has 20 protons and 25 neutrons. What is its mass number?

    45

    Mass number counts protons and neutrons: 20 + 25 = 45.

  11. 11. An atom has 18 protons and 24 neutrons. What is its mass number?

    42

    Mass number counts protons and neutrons: 18 + 24 = 42.

  12. 12. An atom has 14 protons and 19 neutrons. What is its mass number?

    33

    Mass number counts protons and neutrons: 14 + 19 = 33.

12 questions · Seed 53 · Age guidance, not curriculum certification