Electron Arrangement Worksheet | Atomic Model Activity - Free Printable

Absolutely! Let’s solve this “Electron Arrangement” worksheet step by step using the Bohr model and basic atomic structure knowledge.

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## 🧪 Key Concepts to Remember:

- Atomic Number (Z) = Number of protons in the nucleus.
- In a neutral atom, number of electrons = number of protons.
- Atomic Mass (A) ≈ protons + neutrons (rounded to nearest whole number).
- Neutrons = Atomic Mass – Atomic Number.
- Bohr Model: Electrons orbit in shells (energy levels). The maximum electrons per shell are:
- 1st shell: up to 2 electrons
- 2nd shell: up to 8 electrons
- 3rd shell: up to 18 (but for these elements, we only need up to 8)

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We’ll go element by element.

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# 🔬 LEFT SIDE

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1. Hydrogen (H)

- Atomic Number = 1
- Protons = 1
- Electrons = 1 (neutral atom)
- Neutrons = Atomic Mass – Atomic Number = 1 – 1 = 0 *(most common isotope)*
- Atomic Mass ≈ 1

✔ Bohr Model: 1 electron in the first shell.

Fill in:
- Protons: 1
- Neutrons: 0
- Electrons: 1
- Atomic Number: 1
- Atomic Mass: 1

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2. Carbon (C)

- Atomic Number = 6
- Protons = 6
- Electrons = 6
- Atomic Mass ≈ 12
- Neutrons = 12 – 6 = 6

✔ Bohr Model:
- 1st shell: 2 electrons
- 2nd shell: 4 electrons (total 6)

Fill in:
- Protons: 6
- Neutrons: 6
- Electrons: 6
- Atomic Number: 6
- Atomic Mass: 12

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3. Oxygen (O)

- Atomic Number = 8
- Protons = 8
- Electrons = 8
- Atomic Mass ≈ 16
- Neutrons = 16 – 8 = 8

✔ Bohr Model:
- 1st shell: 2 electrons
- 2nd shell: 6 electrons (total 8)

Fill in:
- Protons: 8
- Neutrons: 8
- Electrons: 8
- Atomic Number: 8
- Atomic Mass: 16

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# 🔬 RIGHT SIDE

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4. Sulfur (S)

- Atomic Number = 16
- Protons = 16
- Electrons = 16
- Atomic Mass ≈ 32
- Neutrons = 32 – 16 = 16

✔ Bohr Model:
- 1st shell: 2
- 2nd shell: 8
- 3rd shell: 6 (total 16)

Fill in:
- Protons: 16
- Neutrons: 16
- Electrons: 16
- Atomic Number: 16
- Atomic Mass: 32

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5. Nitrogen (N)

- Atomic Number = 7
- Protons = 7
- Electrons = 7
- Atomic Mass ≈ 14
- Neutrons = 14 – 7 = 7

✔ Bohr Model:
- 1st shell: 2
- 2nd shell: 5 (total 7)

Fill in:
- Protons: 7
- Neutrons: 7
- Electrons: 7
- Atomic Number: 7
- Atomic Mass: 14

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6. Boron (B)

- Atomic Number = 5
- Protons = 5
- Electrons = 5
- Atomic Mass ≈ 11
- Neutrons = 11 – 5 = 6

✔ Bohr Model:
- 1st shell: 2
- 2nd shell: 3 (total 5)

Fill in:
- Protons: 5
- Neutrons: 6
- Electrons: 5
- Atomic Number: 5
- Atomic Mass: 11

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7. Helium (He)

- Atomic Number = 2
- Protons = 2
- Electrons = 2
- Atomic Mass ≈ 4
- Neutrons = 4 – 2 = 2

✔ Bohr Model:
- 1st shell: 2 electrons (full shell!)

Fill in:
- Protons: 2
- Neutrons: 2
- Electrons: 2
- Atomic Number: 2
- Atomic Mass: 4

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## ✔ FINAL ANSWER SUMMARY:

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LEFT SIDE

#### Hydrogen
- Protons: 1
- Neutrons: 0
- Electrons: 1
- Atomic Number: 1
- Atomic Mass: 1

#### Carbon
- Protons: 6
- Neutrons: 6
- Electrons: 6
- Atomic Number: 6
- Atomic Mass: 12

#### Oxygen
- Protons: 8
- Neutrons: 8
- Electrons: 8
- Atomic Number: 8
- Atomic Mass: 16

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RIGHT SIDE

#### Sulfur
- Protons: 16
- Neutrons: 16
- Electrons: 16
- Atomic Number: 16
- Atomic Mass: 32

#### Nitrogen
- Protons: 7
- Neutrons: 7
- Electrons: 7
- Atomic Number: 7
- Atomic Mass: 14

#### Boron
- Protons: 5
- Neutrons: 6
- Electrons: 5
- Atomic Number: 5
- Atomic Mass: 11

#### Helium
- Protons: 2
- Neutrons: 2
- Electrons: 2
- Atomic Number: 2
- Atomic Mass: 4

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## 🖍️ For the Bohr Models:

Draw the correct number of electrons in each shell as described above.

Example for Carbon:
- First circle (innermost): place 2 dots (electrons)
- Second circle: place 4 dots (electrons)

Do this for all elements — remember to fill inner shells first!

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Let me know if you’d like a visual sketch of any Bohr model! 😊