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 1 protons and 29 neutrons. What is its mass number?
1 p⁺ · 29 n⁰ · A = Z + N = ?
2. An atom has 5 protons and 5 neutrons. What is its mass number?
5 p⁺ · 5 n⁰ · A = Z + N = ?
3. An atom has 18 protons and 1 neutrons. What is its mass number?
18 p⁺ · 1 n⁰ · A = Z + N = ?
4. An atom has 19 protons and 5 neutrons. What is its mass number?
19 p⁺ · 5 n⁰ · A = Z + N = ?
5. An atom has 6 protons and 12 neutrons. What is its mass number?
6 p⁺ · 12 n⁰ · A = Z + N = ?
6. An atom has 11 protons and 19 neutrons. What is its mass number?
11 p⁺ · 19 n⁰ · A = Z + N = ?
7. An atom has 12 protons and 16 neutrons. What is its mass number?
12 p⁺ · 16 n⁰ · A = Z + N = ?
8. An atom has 7 protons and 16 neutrons. What is its mass number?
7 p⁺ · 16 n⁰ · A = Z + N = ?
9. An atom has 1 protons and 7 neutrons. What is its mass number?
1 p⁺ · 7 n⁰ · A = Z + N = ?
10. An atom has 7 protons and 21 neutrons. What is its mass number?
7 p⁺ · 21 n⁰ · A = Z + N = ?
11. An atom has 4 protons and 29 neutrons. What is its mass number?
4 p⁺ · 29 n⁰ · A = Z + N = ?
12. An atom has 17 protons and 5 neutrons. What is its mass number?
17 p⁺ · 5 n⁰ · A = Z + N = ?

12 questions · Seed 44 · 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 1 protons and 29 neutrons. What is its mass number?
30
Mass number counts protons and neutrons: 1 + 29 = 30.
2. An atom has 5 protons and 5 neutrons. What is its mass number?
10
Mass number counts protons and neutrons: 5 + 5 = 10.
3. An atom has 18 protons and 1 neutrons. What is its mass number?
19
Mass number counts protons and neutrons: 18 + 1 = 19.
4. An atom has 19 protons and 5 neutrons. What is its mass number?
24
Mass number counts protons and neutrons: 19 + 5 = 24.
5. An atom has 6 protons and 12 neutrons. What is its mass number?
18
Mass number counts protons and neutrons: 6 + 12 = 18.
6. An atom has 11 protons and 19 neutrons. What is its mass number?
30
Mass number counts protons and neutrons: 11 + 19 = 30.
7. An atom has 12 protons and 16 neutrons. What is its mass number?
28
Mass number counts protons and neutrons: 12 + 16 = 28.
8. An atom has 7 protons and 16 neutrons. What is its mass number?
23
Mass number counts protons and neutrons: 7 + 16 = 23.
9. An atom has 1 protons and 7 neutrons. What is its mass number?
8
Mass number counts protons and neutrons: 1 + 7 = 8.
10. An atom has 7 protons and 21 neutrons. What is its mass number?
28
Mass number counts protons and neutrons: 7 + 21 = 28.
11. An atom has 4 protons and 29 neutrons. What is its mass number?
33
Mass number counts protons and neutrons: 4 + 29 = 33.
12. An atom has 17 protons and 5 neutrons. What is its mass number?
22
Mass number counts protons and neutrons: 17 + 5 = 22.

12 questions · Seed 44 · 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 1 protons and 29 neutrons. What is its mass number?
1 p⁺ · 29 n⁰ · A = Z + N = ?
2. An atom has 5 protons and 5 neutrons. What is its mass number?
5 p⁺ · 5 n⁰ · A = Z + N = ?
3. An atom has 18 protons and 1 neutrons. What is its mass number?
18 p⁺ · 1 n⁰ · A = Z + N = ?
4. An atom has 19 protons and 5 neutrons. What is its mass number?
19 p⁺ · 5 n⁰ · A = Z + N = ?
5. An atom has 6 protons and 12 neutrons. What is its mass number?
6 p⁺ · 12 n⁰ · A = Z + N = ?
6. An atom has 11 protons and 19 neutrons. What is its mass number?
11 p⁺ · 19 n⁰ · A = Z + N = ?
7. An atom has 12 protons and 16 neutrons. What is its mass number?
12 p⁺ · 16 n⁰ · A = Z + N = ?
8. An atom has 7 protons and 16 neutrons. What is its mass number?
7 p⁺ · 16 n⁰ · A = Z + N = ?
9. An atom has 1 protons and 7 neutrons. What is its mass number?
1 p⁺ · 7 n⁰ · A = Z + N = ?
10. An atom has 7 protons and 21 neutrons. What is its mass number?
7 p⁺ · 21 n⁰ · A = Z + N = ?
11. An atom has 4 protons and 29 neutrons. What is its mass number?
4 p⁺ · 29 n⁰ · A = Z + N = ?
12. An atom has 17 protons and 5 neutrons. What is its mass number?
17 p⁺ · 5 n⁰ · A = Z + N = ?

12 questions · Seed 44 · 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 1 protons and 29 neutrons. What is its mass number?
30
Mass number counts protons and neutrons: 1 + 29 = 30.
2. An atom has 5 protons and 5 neutrons. What is its mass number?
10
Mass number counts protons and neutrons: 5 + 5 = 10.
3. An atom has 18 protons and 1 neutrons. What is its mass number?
19
Mass number counts protons and neutrons: 18 + 1 = 19.
4. An atom has 19 protons and 5 neutrons. What is its mass number?
24
Mass number counts protons and neutrons: 19 + 5 = 24.
5. An atom has 6 protons and 12 neutrons. What is its mass number?
18
Mass number counts protons and neutrons: 6 + 12 = 18.
6. An atom has 11 protons and 19 neutrons. What is its mass number?
30
Mass number counts protons and neutrons: 11 + 19 = 30.
7. An atom has 12 protons and 16 neutrons. What is its mass number?
28
Mass number counts protons and neutrons: 12 + 16 = 28.
8. An atom has 7 protons and 16 neutrons. What is its mass number?
23
Mass number counts protons and neutrons: 7 + 16 = 23.
9. An atom has 1 protons and 7 neutrons. What is its mass number?
8
Mass number counts protons and neutrons: 1 + 7 = 8.
10. An atom has 7 protons and 21 neutrons. What is its mass number?
28
Mass number counts protons and neutrons: 7 + 21 = 28.
11. An atom has 4 protons and 29 neutrons. What is its mass number?
33
Mass number counts protons and neutrons: 4 + 29 = 33.
12. An atom has 17 protons and 5 neutrons. What is its mass number?
22
Mass number counts protons and neutrons: 17 + 5 = 22.

12 questions · Seed 44 · Age guidance, not curriculum certification