Chemistry Worksheets - Free Printable

Let's solve the problem step by step.

The task asks you to identify the chemical symbol, atomic number, and electron configuration for sodium, chlorine, and aluminum, based on the atomic diagrams shown in the image.

We are given three electron shell diagrams (Bohr models). Each diagram shows concentric circles representing electron shells, with dots representing electrons.

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Step 1: Understand the diagrams

Each circle represents an energy level (shell), and the dots represent electrons.

- The first shell (innermost) holds up to 2 electrons.
- The second shell holds up to 8 electrons.
- The third shell holds up to 8 electrons (for these elements).

Let’s analyze each diagram:

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Diagram 1 (Left):

- Shell 1: 2 electrons
- Shell 2: 8 electrons
- Shell 3: 1 electron

Total electrons = 2 + 8 + 1 = 11

This corresponds to Sodium (Na):
- Atomic number = 11
- Electron configuration = 1s² 2s² 2p⁶ 3s¹ or 2, 8, 1

✔ This is Sodium.

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Diagram 2 (Middle):

- Shell 1: 2 electrons
- Shell 2: 8 electrons
- Shell 3: 7 electrons

Total electrons = 2 + 8 + 7 = 17

This corresponds to Chlorine (Cl):
- Atomic number = 17
- Electron configuration = 1s² 2s² 2p⁶ 3s² 3p⁵ or 2, 8, 7

✔ This is Chlorine.

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Diagram 3 (Right):

- Shell 1: 2 electrons
- Shell 2: 8 electrons
- Shell 3: 3 electrons

Total electrons = 2 + 8 + 3 = 13

This corresponds to Aluminum (Al):
- Atomic number = 13
- Electron configuration = 1s² 2s² 2p⁶ 3s² 3p¹ or 2, 8, 3

✔ This is Aluminum.

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Final Answer:

| Element | Chemical Symbol | Atomic Number | Electron Configuration |
|------------|------------------|---------------|-------------------------|
| Sodium | Na | 11 | 2, 8, 1 |
| Chlorine | Cl | 17 | 2, 8, 7 |
| Aluminum | Al | 13 | 2, 8, 3 |

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Summary:

- Sodium (Na): 11 electrons → 2, 8, 1
- Chlorine (Cl): 17 electrons → 2, 8, 7
- Aluminum (Al): 13 electrons → 2, 8, 3

These match the electron shell diagrams from left to right: Sodium, Chlorine, Aluminum.

✔ Matched correctly!