What are the parts of the atom? worksheet - Free Printable

Here's the completed worksheet with answers and explanations.

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## Lesson Review

1. The first scientist to suggest that atoms contain smaller particles was _J.J. Thomson_ of England.
> *Explanation:* J.J. Thomson discovered the electron in 1897 through his cathode ray tube experiments, proving that atoms are not indivisible but contain smaller, negatively charged particles.

2. Positively charged particles are called _protons_.
> *Explanation:* Protons are subatomic particles found in the nucleus of an atom and carry a positive electric charge (+1).

3. Bohr proposed that electrons in an atom are found in _energy levels (or orbits)_.
> *Explanation:* Niels Bohr’s model (1913) suggested that electrons orbit the nucleus in specific, quantized energy levels or shells.

4. Negatively charged particles are called _electrons_.
> *Explanation:* Electrons are tiny, negatively charged particles that orbit the nucleus and are involved in chemical bonding.

5. Rutherford found that an atom is made up mostly of _empty space_.
> *Explanation:* In his gold foil experiment (1911), Rutherford observed that most alpha particles passed straight through the foil, indicating atoms are mostly empty space with a dense central nucleus.

6. The center, or core, of an atom is called the _nucleus_.
> *Explanation:* The nucleus contains protons and neutrons and is at the center of the atom.

7. Surrounding the core of an atom is a cloud of very small particles called _electrons_.
> *Explanation:* Electrons exist in regions around the nucleus called electron clouds or orbitals (in modern quantum models).

8. Today, energy levels are used to predict the location of an atom’s _electrons_.
> *Explanation:* Energy levels (or electron shells) help scientists determine where electrons are likely to be found around the nucleus.

9. Neutral particles are called _neutrons_.
> *Explanation:* Neutrons have no electric charge (neutral) and reside in the nucleus alongside protons.

10. Rutherford found that _protons_ are located in the core of an atom.
> *Explanation:* While Rutherford didn’t name the proton himself, his discovery of the nucleus led to the identification of positively charged particles (later named protons) within it. He later worked with others to identify the proton as the nucleus of hydrogen.

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## Skill Challenge: Comparing & Classifying

Write “Yes” or “No” for each particle:

| Statement | Proton | Neutron | Electron |
|-------------------------------|--------|---------|----------|
| 1. Does not have an electric charge | No | Yes | No |
> *Neutrons are neutral; protons are +, electrons are –.*

| 2. Found in the nucleus | Yes | Yes | No |
> *Protons and neutrons make up the nucleus; electrons orbit outside.*

| 3. Positively charged | Yes | No | No |
> *Only protons carry a positive charge.*

| 4. Moves in energy levels | No | No | Yes |
> *Electrons occupy energy levels/orbitals; protons and neutrons are confined to the nucleus.*

| 5. Negatively charged | No | No | Yes |
> *Electrons are the only negatively charged subatomic particles listed.*

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✔ Final Answer Summary:

Lesson Review Answers:
1. J.J. Thomson
2. protons
3. energy levels (or orbits)
4. electrons
5. empty space
6. nucleus
7. electrons
8. electrons
9. neutrons
10. protons

Skill Challenge Table:

| Statement | Proton | Neutron | Electron |
|-------------------------------|--------|---------|----------|
| 1. Does not have an electric charge | No | Yes | No |
| 2. Found in the nucleus | Yes | Yes | No |
| 3. Positively charged | Yes | No | No |
| 4. Moves in energy levels | No | No | Yes |
| 5. Negatively charged | No | No | Yes |

Let me know if you’d like diagrams or further explanations!