Atomic Number, Mass Number, and Isotopes - Worksheet | Distance ... - Free Printable

Let's solve each question step by step.

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Q.2: Fill in the table for isotopes of hydrogen

We are given three isotopes of hydrogen: Protium, Deuterium, and Tritium.

Each isotope has:
- The same number of protons (since they are all hydrogen),
- But different numbers of neutrons.

The general notation is:

> $ ^A_Z\text{X} $

Where:
- $ A $ = mass number (protons + neutrons)
- $ Z $ = atomic number (number of protons)

For hydrogen:
- Atomic number $ Z = 1 $ → So, all hydrogen isotopes have 1 proton

Now let’s analyze each:

#### Protium: $ ^1_1\text{H} $
- Mass number = 1
- Protons = 1
- Neutrons = Mass number – Protons = 1 – 1 = 0

#### Deuterium: $ ^2_1\text{H} $
- Mass number = 2
- Protons = 1
- Neutrons = 2 – 1 = 1

#### Tritium: $ ^3_1\text{H} $
- Mass number = 3
- Protons = 1
- Neutrons = 3 – 1 = 2

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✔ Completed Table:

| Isotopes of Hydrogen | Protium | Deuterium | Tritium |
|----------------------|--------|----------|---------|
| Number of Protons | 1 | 1 | 1 |
| Number of Neutrons | 0 | 1 | 2 |

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Q.3: Fill in the table for isotopes of carbon

Given: Carbon-12, Carbon-13, Carbon-14

All are isotopes of carbon → same atomic number, different mass numbers.

Carbon has atomic number = 6 → so 6 protons in each.

Now:

#### Carbon-12: $ ^{12}_6\text{C} $
- Mass number = 12
- Protons = 6
- Neutrons = 12 – 6 = 6

#### Carbon-13: $ ^{13}_6\text{C} $
- Mass number = 13
- Protons = 6
- Neutrons = 13 – 6 = 7

#### Carbon-14: $ ^{14}_6\text{C} $
- Mass number = 14
- Protons = 6
- Neutrons = 14 – 6 = 8

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✔ Completed Table:

| Isotopes of Carbon | Carbon-12 | Carbon-13 | Carbon-14 |
|--------------------|-----------|-----------|-----------|
| Number of Protons | 6 | 6 | 6 |
| Number of Neutrons | 6 | 7 | 8 |

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Q.4: An atom has an atomic number of 14 and a mass number of 29. How many neutrons are there?

We use the formula:

> Number of neutrons = Mass number – Atomic number

Given:
- Mass number = 29
- Atomic number = 14

So:

> Neutrons = 29 – 14 = 15

✔ Answer: b) 15

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✔ Final Answers:

Q.2:
- Protium: 1 proton, 0 neutrons
- Deuterium: 1 proton, 1 neutron
- Tritium: 1 proton, 2 neutrons

Q.3:
- Carbon-12: 6 protons, 6 neutrons
- Carbon-13: 6 protons, 7 neutrons
- Carbon-14: 6 protons, 8 neutrons

Q.4: b) 15

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