atom structure worksheet - Free Printable

Let's solve this step-by-step based on the image you've described. It appears to be a worksheet titled "Your Guide to The Atom" that covers atomic structure, subatomic particles, and how to determine various properties of an atom.

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🔍 Step 1: Understand the Diagram

There is a diagram of an atom with:
- A nucleus in the center (red and green spheres).
- Electrons orbiting in shells (blue dots on circular paths).

We also have several labeled boxes and tables to fill in.

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✔ Part A: Labeling the Atomic Structure

#### 1. Atom Shell Number & Electrons it Can Hold

| Atom Shell Number | Electrons it can hold |
|-------------------|------------------------|
| 1 | 2 |
| 2 | 8 |
| 3 | 18 |

> Explanation:
> - The first shell (n=1) holds up to 2 electrons.
> - The second shell (n=2) holds up to 8 electrons.
> - The third shell (n=3) holds up to 18 electrons, but often only 8 are filled in main group elements.

So, fill in:
- Shell 1 → 2
- Shell 2 → 8
- Shell 3 → 18

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✔ Part B: Subatomic Particles Table

| Subatomic Particle | Charge | Mass | Location in Atom |
|--------------------|--------|------|------------------|
| Electron | -1 | ~0 | Electron cloud |
| Proton | +1 | 1 | Nucleus |
| Neutron | 0 | 1 | Nucleus |

Given:
- One row has charge = -1, mass ≈ 0 → Electron
- One row has charge = 0, mass = 1, location = Nucleus → Neutron
- So the missing particle with charge = +1, mass = 1, location = Nucleus → Proton

✔ Fill in:
- Row 1: Electron
- Row 2: Proton
- Row 3: Neutron

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✔ Part C: Finding Number of Neutrons

> "To find the number of neutrons in an atom you need to..."

👉 Subtract the atomic number from the mass number.

So fill in:
> To find the number of neutrons in an atom you need to subtract the atomic number from the mass number.

Or more clearly:
> Mass number – Atomic number = Number of neutrons

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✔ Part D: Lithium Example (Li)

Given:
```
+7
Li
3
```

This is the isotopic notation for lithium.

Breakdown:
- Top number (7) = Mass number (protons + neutrons)
- Bottom number (3) = Atomic number (number of protons)
- Symbol: Li

Now fill in:

#### Atomic Symbol: Li

#### Number of protons: 3
> Because atomic number = number of protons.

#### Number of electrons: 3
> In a neutral atom, electrons = protons.

#### Number of neutrons: 4
> Mass number – Atomic number = 7 – 3 = 4

So:
- Number of neutrons: 4
- Number of protons: 3
- Number of electrons: 3

Also, the statement says:
> "The total number of protons and neutrons is equal to the number of mass number."

So fill in:
> The total number of protons and neutrons is equal to the number of mass number.

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✔ Final Answer Summary

#### 1. Shell Electron Capacity:
| Shell | Max Electrons |
|-------|---------------|
| 1 | 2 |
| 2 | 8 |
| 3 | 18 |

#### 2. Subatomic Particles Table:

| Particle | Charge | Mass | Location |
|---------|--------|------|----------------|
| Electron | -1 | ~0 | Electron cloud |
| Proton | +1 | 1 | Nucleus |
| Neutron | 0 | 1 | Nucleus |

#### 3. Neutron Calculation:
> To find the number of neutrons in an atom you need to subtract the atomic number from the mass number.

#### 4. For Lithium (Li):
- Atomic Symbol: Li
- Atomic Number: 3
- Mass Number: 7
- Number of protons: 3
- Number of electrons: 3
- Number of neutrons: 4
- The total number of protons and neutrons is equal to the mass number.

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🧠 Bonus: Labeling the Diagram

From the central atom diagram:
- Nucleus → red and green spheres in center (protons and neutrons)
- Electrons → blue dots orbiting
- Shells → circles around nucleus
- Outermost shell may be labeled as valence shell

You can label:
- Left side: Electron
- Right side: Nucleus
- Bottom: Shell 1
- Top: Shell 2
- (If shown) Outer shell: Valence electrons

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