Element practice worksheet for learning atomic structure and identifying elements.

Let's solve this step-by-step based on the information provided in the image.

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Understanding the Labels:

For each element, the notation is:

```
Atomic Number
↑
X (Atomic Symbol)
↓
Atomic Mass
```

- Atomic Number = number of protons = number of electrons (in a neutral atom).
- Atomic Mass ≈ total mass of protons + neutrons.
- Number of Neutrons = Atomic Mass − Atomic Number

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Now, let’s go through each element one by one.

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1. He (Helium)

- Atomic Number = 2 → # protons = 2
- Atomic Mass = 4 → # neutrons = 4 − 2 = 2
- Element: Helium

✔ Answer:
- Element: Helium
- # protons: 2
- # neutrons: 2

---

2. Fe (Iron)

- Atomic Number = 26 → # protons = 26
- Atomic Mass = 56 → # neutrons = 56 − 26 = 30
- Element: Iron

✔ Answer:
- Element: Iron
- # protons: 26
- # neutrons: 30

---

3. Al (Aluminum)

- Atomic Number = 13 → # protons = 13
- Atomic Mass = 27 → # neutrons = 27 − 13 = 14
- Element: Aluminum

✔ Answer:
- Element: Aluminum
- # protons: 13
- # neutrons: 14

---

4. Ca (Calcium)

- Atomic Number = 20 → # protons = 20
- Atomic Mass = 40 → # neutrons = 40 − 20 = 20
- Element: Calcium

✔ Answer:
- Element: Calcium
- # protons: 20
- # neutrons: 20

---

5. Ne (Neon)

- Atomic Number = 10 → # protons = 10
- Atomic Mass = 20 → # neutrons = 20 − 10 = 10
- Element: Neon

✔ Answer:
- Element: Neon
- # protons: 10
- # neutrons: 10

---

6. C (Carbon)

- Atomic Number = 6 → # protons = 6
- Atomic Mass = 12 → # neutrons = 12 − 6 = 6
- Element: Carbon

✔ Answer:
- Element: Carbon
- # protons: 6
- # neutrons: 6

---

7. F (Fluorine)

- Atomic Number = 9 → # protons = 9
- Atomic Mass = 19 → # neutrons = 19 − 9 = 10
- Element: Fluorine

✔ Answer:
- Element: Fluorine
- # protons: 9
- # neutrons: 10

---

8. Cl (Chlorine)

- Atomic Number = 17 → # protons = 17
- Atomic Mass = 35 → # neutrons = 35 − 17 = 18
- Element: Chlorine

✔ Answer:
- Element: Chlorine
- # protons: 17
- # neutrons: 18

---

9. Na (Sodium)

- Atomic Number = 11 → # protons = 11
- Atomic Mass = 23 → # neutrons = 23 − 11 = 12
- Element: Sodium

✔ Answer:
- Element: Sodium
- # protons: 11
- # neutrons: 12

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✔ Final Completed Table:

| Element | # Protons | # Neutrons |
|--------|-----------|------------|
| He | 2 | 2 |
| Fe | 26 | 30 |
| Al | 13 | 14 |
| Ca | 20 | 20 |
| Ne | 10 | 10 |
| C | 6 | 6 |
| F | 9 | 10 |
| Cl | 17 | 18 |
| Na | 11 | 12 |

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🔍 Summary of Key Concepts:

- Atomic Number = # of protons (and electrons in neutral atoms)
- Atomic Mass ≈ total mass of protons and neutrons
- # Neutrons = Atomic Mass − Atomic Number

This method works for most elements, especially when using the most common isotopes (like carbon-12, oxygen-16, etc.).

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