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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Worksheet StudioPractice pack · Ages 16-18

Protons, neutrons & mass number

Take your time. Show your thinking.

1. An atom has 14 protons and 1 neutrons. What is its mass number?
14 p⁺ · 1 n⁰ · A = Z + N = ?
2. An atom has 6 protons and 14 neutrons. What is its mass number?
6 p⁺ · 14 n⁰ · A = Z + N = ?
3. An atom has 17 protons and 25 neutrons. What is its mass number?
17 p⁺ · 25 n⁰ · A = Z + N = ?
4. An atom has 6 protons and 12 neutrons. What is its mass number?
6 p⁺ · 12 n⁰ · A = Z + N = ?
5. An atom has 13 protons and 8 neutrons. What is its mass number?
13 p⁺ · 8 n⁰ · A = Z + N = ?
6. An atom has 20 protons and 16 neutrons. What is its mass number?
20 p⁺ · 16 n⁰ · A = Z + N = ?
7. An atom has 18 protons and 3 neutrons. What is its mass number?
18 p⁺ · 3 n⁰ · A = Z + N = ?
8. An atom has 18 protons and 15 neutrons. What is its mass number?
18 p⁺ · 15 n⁰ · A = Z + N = ?
9. An atom has 2 protons and 1 neutrons. What is its mass number?
2 p⁺ · 1 n⁰ · A = Z + N = ?
10. An atom has 17 protons and 13 neutrons. What is its mass number?
17 p⁺ · 13 n⁰ · A = Z + N = ?
11. An atom has 17 protons and 16 neutrons. What is its mass number?
17 p⁺ · 16 n⁰ · A = Z + N = ?
12. An atom has 8 protons and 17 neutrons. What is its mass number?
8 p⁺ · 17 n⁰ · A = Z + N = ?

12 questions · Seed 52 · 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. An atom has 14 protons and 1 neutrons. What is its mass number?
15
Mass number counts protons and neutrons: 14 + 1 = 15.
2. An atom has 6 protons and 14 neutrons. What is its mass number?
20
Mass number counts protons and neutrons: 6 + 14 = 20.
3. An atom has 17 protons and 25 neutrons. What is its mass number?
42
Mass number counts protons and neutrons: 17 + 25 = 42.
4. An atom has 6 protons and 12 neutrons. What is its mass number?
18
Mass number counts protons and neutrons: 6 + 12 = 18.
5. An atom has 13 protons and 8 neutrons. What is its mass number?
21
Mass number counts protons and neutrons: 13 + 8 = 21.
6. An atom has 20 protons and 16 neutrons. What is its mass number?
36
Mass number counts protons and neutrons: 20 + 16 = 36.
7. An atom has 18 protons and 3 neutrons. What is its mass number?
21
Mass number counts protons and neutrons: 18 + 3 = 21.
8. An atom has 18 protons and 15 neutrons. What is its mass number?
33
Mass number counts protons and neutrons: 18 + 15 = 33.
9. An atom has 2 protons and 1 neutrons. What is its mass number?
3
Mass number counts protons and neutrons: 2 + 1 = 3.
10. An atom has 17 protons and 13 neutrons. What is its mass number?
30
Mass number counts protons and neutrons: 17 + 13 = 30.
11. An atom has 17 protons and 16 neutrons. What is its mass number?
33
Mass number counts protons and neutrons: 17 + 16 = 33.
12. An atom has 8 protons and 17 neutrons. What is its mass number?
25
Mass number counts protons and neutrons: 8 + 17 = 25.

12 questions · Seed 52 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 16-18

Protons, neutrons & mass number

Take your time. Show your thinking.

1. An atom has 14 protons and 1 neutrons. What is its mass number?
14 p⁺ · 1 n⁰ · A = Z + N = ?
2. An atom has 6 protons and 14 neutrons. What is its mass number?
6 p⁺ · 14 n⁰ · A = Z + N = ?
3. An atom has 17 protons and 25 neutrons. What is its mass number?
17 p⁺ · 25 n⁰ · A = Z + N = ?
4. An atom has 6 protons and 12 neutrons. What is its mass number?
6 p⁺ · 12 n⁰ · A = Z + N = ?
5. An atom has 13 protons and 8 neutrons. What is its mass number?
13 p⁺ · 8 n⁰ · A = Z + N = ?
6. An atom has 20 protons and 16 neutrons. What is its mass number?
20 p⁺ · 16 n⁰ · A = Z + N = ?
7. An atom has 18 protons and 3 neutrons. What is its mass number?
18 p⁺ · 3 n⁰ · A = Z + N = ?
8. An atom has 18 protons and 15 neutrons. What is its mass number?
18 p⁺ · 15 n⁰ · A = Z + N = ?
9. An atom has 2 protons and 1 neutrons. What is its mass number?
2 p⁺ · 1 n⁰ · A = Z + N = ?
10. An atom has 17 protons and 13 neutrons. What is its mass number?
17 p⁺ · 13 n⁰ · A = Z + N = ?
11. An atom has 17 protons and 16 neutrons. What is its mass number?
17 p⁺ · 16 n⁰ · A = Z + N = ?
12. An atom has 8 protons and 17 neutrons. What is its mass number?
8 p⁺ · 17 n⁰ · A = Z + N = ?

12 questions · Seed 52 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 16-18

Protons, neutrons & mass number

Answers and reasoning. Review before teaching.

1. An atom has 14 protons and 1 neutrons. What is its mass number?
15
Mass number counts protons and neutrons: 14 + 1 = 15.
2. An atom has 6 protons and 14 neutrons. What is its mass number?
20
Mass number counts protons and neutrons: 6 + 14 = 20.
3. An atom has 17 protons and 25 neutrons. What is its mass number?
42
Mass number counts protons and neutrons: 17 + 25 = 42.
4. An atom has 6 protons and 12 neutrons. What is its mass number?
18
Mass number counts protons and neutrons: 6 + 12 = 18.
5. An atom has 13 protons and 8 neutrons. What is its mass number?
21
Mass number counts protons and neutrons: 13 + 8 = 21.
6. An atom has 20 protons and 16 neutrons. What is its mass number?
36
Mass number counts protons and neutrons: 20 + 16 = 36.
7. An atom has 18 protons and 3 neutrons. What is its mass number?
21
Mass number counts protons and neutrons: 18 + 3 = 21.
8. An atom has 18 protons and 15 neutrons. What is its mass number?
33
Mass number counts protons and neutrons: 18 + 15 = 33.
9. An atom has 2 protons and 1 neutrons. What is its mass number?
3
Mass number counts protons and neutrons: 2 + 1 = 3.
10. An atom has 17 protons and 13 neutrons. What is its mass number?
30
Mass number counts protons and neutrons: 17 + 13 = 30.
11. An atom has 17 protons and 16 neutrons. What is its mass number?
33
Mass number counts protons and neutrons: 17 + 16 = 33.
12. An atom has 8 protons and 17 neutrons. What is its mass number?
25
Mass number counts protons and neutrons: 8 + 17 = 25.

12 questions · Seed 52 · Age guidance, not curriculum certification