BOHR Model Worksheet: Draw the Inner electrons and the valence ... - Free Printable

Let's solve this Bohr Model Worksheet step by step. The goal is to draw the electron configuration for each element using the Bohr model, where:

- Inner electrons (core electrons) are shown in blue.
- Valence electrons (outermost shell electrons) are shown in red.
- We use dots (•) or X’s to represent electrons.
- The formula $ 2n^2 $ gives the maximum number of electrons per energy level (shell), where $ n $ is the shell number.

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🔹 Step-by-step Instructions:

1. Find the atomic number of each element (number of protons = number of electrons in neutral atom).
2. Fill electrons into shells starting from the innermost shell, following $ 2n^2 $ rule:
- Shell 1 (n=1): max 2 electrons
- Shell 2 (n=2): max 8 electrons
- Shell 3 (n=3): max 18 electrons
- But for these elements, we only need up to 3 shells.
3. Draw the electrons on the circles (shells):
- Inner electrons → blue
- Valence electrons → red

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Now let's go through each element:

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✔ 1. Sodium (Na) – Atomic Number: 11

- Electrons: 11
- Shell 1 (n=1): 2 electrons → blue
- Shell 2 (n=2): 8 electrons → blue
- Shell 3 (n=3): 1 electron → red (valence)

Drawing:
- First circle (innermost): 2 blue dots
- Second circle: 8 blue dots
- Third circle: 1 red dot

> Valence electrons: 1

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✔ 2. Aluminum (Al) – Atomic Number: 13

- Electrons: 13
- Shell 1: 2 → blue
- Shell 2: 8 → blue
- Shell 3: 3 → red

Drawing:
- First: 2 blue
- Second: 8 blue
- Third: 3 red dots

> Valence electrons: 3

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✔ 3. Carbon (C) – Atomic Number: 6

- Electrons: 6
- Shell 1: 2 → blue
- Shell 2: 4 → red (since it's outermost)

Drawing:
- First: 2 blue
- Second: 4 red dots

> Valence electrons: 4

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✔ 4. Silicon (Si) – Atomic Number: 14

- Electrons: 14
- Shell 1: 2 → blue
- Shell 2: 8 → blue
- Shell 3: 4 → red

Drawing:
- First: 2 blue
- Second: 8 blue
- Third: 4 red dots

> Valence electrons: 4

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✔ 5. Oxygen (O) – Atomic Number: 8

- Electrons: 8
- Shell 1: 2 → blue
- Shell 2: 6 → red

Drawing:
- First: 2 blue
- Second: 6 red dots

> Valence electrons: 6

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✔ 6. Chlorine (Cl) – Atomic Number: 17

- Electrons: 17
- Shell 1: 2 → blue
- Shell 2: 8 → blue
- Shell 3: 7 → red

Drawing:
- First: 2 blue
- Second: 8 blue
- Third: 7 red dots

> Valence electrons: 7

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📌 Summary Table:

| Element | Atomic # | Electron Configuration | Valence e⁻ | Shells |
|--------|----------|-------------------------|------------|--------|
| Na | 11 | 2, 8, 1 | 1 | 2+8+1 |
| Al | 13 | 2, 8, 3 | 3 | 2+8+3 |
| C | 6 | 2, 4 | 4 | 2+4 |
| Si | 14 | 2, 8, 4 | 4 | 2+8+4 |
| O | 8 | 2, 6 | 6 | 2+6 |
| Cl | 17 | 2, 8, 7 | 7 | 2+8+7 |

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🖼️ How to Draw Each One (Text Representation):

#### Sodium (Na)
```
•• ← Shell 1 (blue)
••••••••← Shell 2 (blue)
• ← Shell 3 (red)
```

(Use blue for first two shells, red for outer one)

#### Aluminum (Al)
```
•• ← Shell 1 (blue)
••••••••← Shell 2 (blue)
••• ← Shell 3 (red)
```

#### Carbon (C)
```
•• ← Shell 1 (blue)
•••• ← Shell 2 (red)
```

#### Silicon (Si)
```
•• ← Shell 1 (blue)
••••••••← Shell 2 (blue)
•••• ← Shell 3 (red)
```

#### Oxygen (O)
```
•• ← Shell 1 (blue)
•••••• ← Shell 2 (red)
```

#### Chlorine (Cl)
```
•• ← Shell 1 (blue)
••••••••← Shell 2 (blue)
•••••••← Shell 3 (red)
```

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✔ Final Tips:

- Use dots or X's as instructed.
- Color inner electrons blue, valence electrons red.
- Distribute electrons evenly around each shell (like a clock face).

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Let me know if you'd like a printable version or visual diagrams!