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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Worksheet StudioPractice pack · Ages 13-15

Protons, neutrons & mass number

Take your time. Show your thinking.

1. An atom has 8 protons and 19 neutrons. What is its mass number?
8 p⁺ · 19 n⁰ · A = Z + N = ?
2. An atom has 14 protons and 14 neutrons. What is its mass number?
14 p⁺ · 14 n⁰ · A = Z + N = ?
3. An atom has 10 protons and 7 neutrons. What is its mass number?
10 p⁺ · 7 n⁰ · A = Z + N = ?
4. An atom has 16 protons and 14 neutrons. What is its mass number?
16 p⁺ · 14 n⁰ · A = Z + N = ?
5. An atom has 13 protons and 6 neutrons. What is its mass number?
13 p⁺ · 6 n⁰ · A = Z + N = ?
6. An atom has 7 protons and 13 neutrons. What is its mass number?
7 p⁺ · 13 n⁰ · A = Z + N = ?
7. An atom has 12 protons and 27 neutrons. What is its mass number?
12 p⁺ · 27 n⁰ · A = Z + N = ?
8. An atom has 6 protons and 26 neutrons. What is its mass number?
6 p⁺ · 26 n⁰ · A = Z + N = ?
9. An atom has 11 protons and 10 neutrons. What is its mass number?
11 p⁺ · 10 n⁰ · A = Z + N = ?
10. An atom has 1 protons and 6 neutrons. What is its mass number?
1 p⁺ · 6 n⁰ · A = Z + N = ?
11. An atom has 3 protons and 27 neutrons. What is its mass number?
3 p⁺ · 27 n⁰ · A = Z + N = ?
12. An atom has 7 protons and 11 neutrons. What is its mass number?
7 p⁺ · 11 n⁰ · A = Z + N = ?

12 questions · Seed 50 · 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. An atom has 8 protons and 19 neutrons. What is its mass number?
27
Mass number counts protons and neutrons: 8 + 19 = 27.
2. An atom has 14 protons and 14 neutrons. What is its mass number?
28
Mass number counts protons and neutrons: 14 + 14 = 28.
3. An atom has 10 protons and 7 neutrons. What is its mass number?
17
Mass number counts protons and neutrons: 10 + 7 = 17.
4. An atom has 16 protons and 14 neutrons. What is its mass number?
30
Mass number counts protons and neutrons: 16 + 14 = 30.
5. An atom has 13 protons and 6 neutrons. What is its mass number?
19
Mass number counts protons and neutrons: 13 + 6 = 19.
6. An atom has 7 protons and 13 neutrons. What is its mass number?
20
Mass number counts protons and neutrons: 7 + 13 = 20.
7. An atom has 12 protons and 27 neutrons. What is its mass number?
39
Mass number counts protons and neutrons: 12 + 27 = 39.
8. An atom has 6 protons and 26 neutrons. What is its mass number?
32
Mass number counts protons and neutrons: 6 + 26 = 32.
9. An atom has 11 protons and 10 neutrons. What is its mass number?
21
Mass number counts protons and neutrons: 11 + 10 = 21.
10. An atom has 1 protons and 6 neutrons. What is its mass number?
7
Mass number counts protons and neutrons: 1 + 6 = 7.
11. An atom has 3 protons and 27 neutrons. What is its mass number?
30
Mass number counts protons and neutrons: 3 + 27 = 30.
12. An atom has 7 protons and 11 neutrons. What is its mass number?
18
Mass number counts protons and neutrons: 7 + 11 = 18.

12 questions · Seed 50 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 13-15

Protons, neutrons & mass number

Take your time. Show your thinking.

1. An atom has 8 protons and 19 neutrons. What is its mass number?
8 p⁺ · 19 n⁰ · A = Z + N = ?
2. An atom has 14 protons and 14 neutrons. What is its mass number?
14 p⁺ · 14 n⁰ · A = Z + N = ?
3. An atom has 10 protons and 7 neutrons. What is its mass number?
10 p⁺ · 7 n⁰ · A = Z + N = ?
4. An atom has 16 protons and 14 neutrons. What is its mass number?
16 p⁺ · 14 n⁰ · A = Z + N = ?
5. An atom has 13 protons and 6 neutrons. What is its mass number?
13 p⁺ · 6 n⁰ · A = Z + N = ?
6. An atom has 7 protons and 13 neutrons. What is its mass number?
7 p⁺ · 13 n⁰ · A = Z + N = ?
7. An atom has 12 protons and 27 neutrons. What is its mass number?
12 p⁺ · 27 n⁰ · A = Z + N = ?
8. An atom has 6 protons and 26 neutrons. What is its mass number?
6 p⁺ · 26 n⁰ · A = Z + N = ?
9. An atom has 11 protons and 10 neutrons. What is its mass number?
11 p⁺ · 10 n⁰ · A = Z + N = ?
10. An atom has 1 protons and 6 neutrons. What is its mass number?
1 p⁺ · 6 n⁰ · A = Z + N = ?
11. An atom has 3 protons and 27 neutrons. What is its mass number?
3 p⁺ · 27 n⁰ · A = Z + N = ?
12. An atom has 7 protons and 11 neutrons. What is its mass number?
7 p⁺ · 11 n⁰ · A = Z + N = ?

12 questions · Seed 50 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 13-15

Protons, neutrons & mass number

Answers and reasoning. Review before teaching.

1. An atom has 8 protons and 19 neutrons. What is its mass number?
27
Mass number counts protons and neutrons: 8 + 19 = 27.
2. An atom has 14 protons and 14 neutrons. What is its mass number?
28
Mass number counts protons and neutrons: 14 + 14 = 28.
3. An atom has 10 protons and 7 neutrons. What is its mass number?
17
Mass number counts protons and neutrons: 10 + 7 = 17.
4. An atom has 16 protons and 14 neutrons. What is its mass number?
30
Mass number counts protons and neutrons: 16 + 14 = 30.
5. An atom has 13 protons and 6 neutrons. What is its mass number?
19
Mass number counts protons and neutrons: 13 + 6 = 19.
6. An atom has 7 protons and 13 neutrons. What is its mass number?
20
Mass number counts protons and neutrons: 7 + 13 = 20.
7. An atom has 12 protons and 27 neutrons. What is its mass number?
39
Mass number counts protons and neutrons: 12 + 27 = 39.
8. An atom has 6 protons and 26 neutrons. What is its mass number?
32
Mass number counts protons and neutrons: 6 + 26 = 32.
9. An atom has 11 protons and 10 neutrons. What is its mass number?
21
Mass number counts protons and neutrons: 11 + 10 = 21.
10. An atom has 1 protons and 6 neutrons. What is its mass number?
7
Mass number counts protons and neutrons: 1 + 6 = 7.
11. An atom has 3 protons and 27 neutrons. What is its mass number?
30
Mass number counts protons and neutrons: 3 + 27 = 30.
12. An atom has 7 protons and 11 neutrons. What is its mass number?
18
Mass number counts protons and neutrons: 7 + 11 = 18.

12 questions · Seed 50 · Age guidance, not curriculum certification