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're 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, $ Z = 1 $ (always).

Let’s analyze each:

#### Protium ($ ^1_1\text{H} $)
- Mass number $ A = 1 $
- Atomic number $ Z = 1 $
- So, Number of protons = 1
- Number of neutrons = $ A - Z = 1 - 1 = 0 $

#### Deuterium ($ ^2_1\text{H} $)
- $ A = 2 $
- $ Z = 1 $
- Protons = 1
- Neutrons = $ 2 - 1 = 1 $

#### Tritium ($ ^3_1\text{H} $)
- $ A = 3 $
- $ Z = 1 $
- Protons = 1
- Neutrons = $ 3 - 1 = 2 $

✔ 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 isotopes: Carbon-12, Carbon-13, Carbon-14

All have the symbol $ ^A_6\text{C} $, so atomic number $ Z = 6 $ → 6 protons

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 $

✔ 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 in this atom?

Use the formula:

$$
\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}
$$

$$
= 29 - 14 = 15
$$

✔ 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 neutrons

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