Atomic Theory Worksheet Answers - Free Printable

It looks like you've uploaded an image of a worksheet titled "History of Atomic Theory", which includes portraits of several scientists and text boxes with descriptions related to atomic theory. However, the image appears to be blurred or low-resolution, making it difficult to read the text clearly.

To help you solve the task, I’ll need to:

1. Identify the scientists in the portraits (based on common historical figures in atomic theory).
2. Match each scientist with their correct contribution to atomic theory.
3. Fill in the blanks based on standard knowledge of the history of atomic theory.

Let me analyze what’s visible:

---

Step 1: Identify the Scientists

From left to right, top row:
1. Ernest Rutherford – Known for the nuclear model of the atom.
2. Niels Bohr – Developed the Bohr model of the atom with electron shells.
3. Democritus – Ancient Greek philosopher who first proposed the idea of atoms.
4. John Dalton – Proposed the modern atomic theory in the early 1800s.

Bottom row:
5. James Chadwick – Discovered the neutron.
6. J.J. Thomson – Discovered the electron and proposed the "plum pudding" model.

---

Step 2: Match Contributions

Now let's match these scientists with their key contributions:

#### Democritus (c. 400 BCE)
- Believed matter was made of tiny, indivisible particles called "atoms."
- First philosophical idea of atoms (not scientific evidence).

#### John Dalton (1800s)
- Proposed that all matter is made of atoms.
- Atoms of the same element are identical.
- Atoms combine in simple whole-number ratios.
- Atoms cannot be created or destroyed.

#### J.J. Thomson (1897)
- Discovered the electron using cathode ray experiments.
- Proposed the "plum pudding" model: electrons embedded in a positive sphere.

#### Ernest Rutherford (1911)
- Conducted gold foil experiment.
- Found that the atom has a small, dense, positively charged nucleus.
- Proposed the nuclear model of the atom.

#### Niels Bohr (1913)
- Improved Rutherford’s model by adding quantized electron orbits.
- Electrons orbit the nucleus in fixed energy levels.

#### James Chadwick (1932)
- Discovered the neutron.
- Explained why atomic mass was greater than proton count.

---

Step 3: Likely Matching Exercise

The worksheet likely asks you to:
- Match each scientist with their discovery or model.
- Fill in the blank boxes with the correct names or dates.
- Possibly match quotes or descriptions to the correct person.

---

Example Solution Format (if this were a fill-in-the-blank):

| Scientist | Contribution |
|------------------|--------------|
| Democritus | First to propose the idea of atoms (indivisible particles) |
| John Dalton | Modern atomic theory; atoms are indivisible and combine in ratios |
| J.J. Thomson | Discovered the electron; plum pudding model |
| Ernest Rutherford| Nuclear model; discovered nucleus via gold foil experiment |
| Niels Bohr | Electron energy levels; planetary model |
| James Chadwick | Discovered the neutron |

---

Final Answer (Based on Common Worksheet Structure)

If the worksheet has:
- Portraits labeled A–F
- Blank boxes for names and years
- Descriptions below

Then the correct matching would be:

- Democritus: c. 400 BCE → "Atoms are indivisible"
- Dalton: 1808 → "Atomic theory with elements having unique atoms"
- Thomson: 1897 → "Discovered electron"
- Rutherford: 1911 → "Nuclear model"
- Bohr: 1913 → "Electron shells"
- Chadwick: 1932 → "Discovered neutron"

---

✔ Conclusion:
Without being able to read the exact text due to image quality, I’ve provided the standard answers for a typical “History of Atomic Theory” worksheet. If you can provide clearer text or describe the labels, I can give a more precise solution.

Would you like me to generate a printable version of the corrected worksheet?