Small practice. Bright discoveries.Explore the free starter collection
worksheetstudio.
Sign in
Back to worksheets
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.

New variationTry interactive challengeBrowse templates
Age band:Ages 13-15Ages 16-18

Choose “Save as PDF” to keep a copy. Use your browser’s paper setting for A4 or Letter.

Worksheet StudioPractice pack · Ages 16-18

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 16-18

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 16-18

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 16-18

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