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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 8 protons and 3 neutrons. What is its mass number?

    8 p⁺ · 3 n⁰ · A = Z + N = ?

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

    19 p⁺ · 5 n⁰ · A = Z + N = ?

  3. 3. An atom has 16 protons and 2 neutrons. What is its mass number?

    16 p⁺ · 2 n⁰ · A = Z + N = ?

  4. 4. An atom has 9 protons and 4 neutrons. What is its mass number?

    9 p⁺ · 4 n⁰ · A = Z + N = ?

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

    12 p⁺ · 10 n⁰ · A = Z + N = ?

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

    13 p⁺ · 12 n⁰ · A = Z + N = ?

  7. 7. An atom has 6 protons and 9 neutrons. What is its mass number?

    6 p⁺ · 9 n⁰ · A = Z + N = ?

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

    6 p⁺ · 6 n⁰ · A = Z + N = ?

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

    4 p⁺ · 17 n⁰ · A = Z + N = ?

  10. 10. An atom has 14 protons and 4 neutrons. What is its mass number?

    14 p⁺ · 4 n⁰ · A = Z + N = ?

  11. 11. An atom has 16 protons and 11 neutrons. What is its mass number?

    16 p⁺ · 11 n⁰ · A = Z + N = ?

  12. 12. An atom has 12 protons and 29 neutrons. What is its mass number?

    12 p⁺ · 29 n⁰ · A = Z + N = ?
12 questions · Seed 104732 · 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 8 protons and 3 neutrons. What is its mass number?

    11

    Mass number counts protons and neutrons: 8 + 3 = 11.

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

    24

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

  3. 3. An atom has 16 protons and 2 neutrons. What is its mass number?

    18

    Mass number counts protons and neutrons: 16 + 2 = 18.

  4. 4. An atom has 9 protons and 4 neutrons. What is its mass number?

    13

    Mass number counts protons and neutrons: 9 + 4 = 13.

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

    22

    Mass number counts protons and neutrons: 12 + 10 = 22.

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

    25

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

  7. 7. An atom has 6 protons and 9 neutrons. What is its mass number?

    15

    Mass number counts protons and neutrons: 6 + 9 = 15.

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

    12

    Mass number counts protons and neutrons: 6 + 6 = 12.

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

    21

    Mass number counts protons and neutrons: 4 + 17 = 21.

  10. 10. An atom has 14 protons and 4 neutrons. What is its mass number?

    18

    Mass number counts protons and neutrons: 14 + 4 = 18.

  11. 11. An atom has 16 protons and 11 neutrons. What is its mass number?

    27

    Mass number counts protons and neutrons: 16 + 11 = 27.

  12. 12. An atom has 12 protons and 29 neutrons. What is its mass number?

    41

    Mass number counts protons and neutrons: 12 + 29 = 41.

12 questions · Seed 104732 · 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 8 protons and 3 neutrons. What is its mass number?

    8 p⁺ · 3 n⁰ · A = Z + N = ?

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

    19 p⁺ · 5 n⁰ · A = Z + N = ?

  3. 3. An atom has 16 protons and 2 neutrons. What is its mass number?

    16 p⁺ · 2 n⁰ · A = Z + N = ?

  4. 4. An atom has 9 protons and 4 neutrons. What is its mass number?

    9 p⁺ · 4 n⁰ · A = Z + N = ?

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

    12 p⁺ · 10 n⁰ · A = Z + N = ?

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

    13 p⁺ · 12 n⁰ · A = Z + N = ?

  7. 7. An atom has 6 protons and 9 neutrons. What is its mass number?

    6 p⁺ · 9 n⁰ · A = Z + N = ?

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

    6 p⁺ · 6 n⁰ · A = Z + N = ?

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

    4 p⁺ · 17 n⁰ · A = Z + N = ?

  10. 10. An atom has 14 protons and 4 neutrons. What is its mass number?

    14 p⁺ · 4 n⁰ · A = Z + N = ?

  11. 11. An atom has 16 protons and 11 neutrons. What is its mass number?

    16 p⁺ · 11 n⁰ · A = Z + N = ?

  12. 12. An atom has 12 protons and 29 neutrons. What is its mass number?

    12 p⁺ · 29 n⁰ · A = Z + N = ?
12 questions · Seed 104732 · 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 8 protons and 3 neutrons. What is its mass number?

    11

    Mass number counts protons and neutrons: 8 + 3 = 11.

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

    24

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

  3. 3. An atom has 16 protons and 2 neutrons. What is its mass number?

    18

    Mass number counts protons and neutrons: 16 + 2 = 18.

  4. 4. An atom has 9 protons and 4 neutrons. What is its mass number?

    13

    Mass number counts protons and neutrons: 9 + 4 = 13.

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

    22

    Mass number counts protons and neutrons: 12 + 10 = 22.

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

    25

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

  7. 7. An atom has 6 protons and 9 neutrons. What is its mass number?

    15

    Mass number counts protons and neutrons: 6 + 9 = 15.

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

    12

    Mass number counts protons and neutrons: 6 + 6 = 12.

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

    21

    Mass number counts protons and neutrons: 4 + 17 = 21.

  10. 10. An atom has 14 protons and 4 neutrons. What is its mass number?

    18

    Mass number counts protons and neutrons: 14 + 4 = 18.

  11. 11. An atom has 16 protons and 11 neutrons. What is its mass number?

    27

    Mass number counts protons and neutrons: 16 + 11 = 27.

  12. 12. An atom has 12 protons and 29 neutrons. What is its mass number?

    41

    Mass number counts protons and neutrons: 12 + 29 = 41.

12 questions · Seed 104732 · Age guidance, not curriculum certification