Solved Protons. Neutrons, and Electrons Practice Worksheet | Chegg.com - Free Printable

You're working on a Protons, Neutrons, and Electrons Practice Worksheet. The goal is to fill in the missing values for each element using the periodic table and the following rules:

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🔑 Key Rules (as given in your worksheet):

- # Protons = Atomic Number
- # Electrons = Protons *(in a neutral atom — which we assume unless told otherwise)*
- # Neutrons = Atomic Mass – Atomic Number
*(Use the mass number, usually the whole number closest to the atomic weight — round if needed)*

> ⚠️ Note: In many cases, especially with isotopes, mass number may not be exactly the same as the atomic weight listed on the periodic table. But for this worksheet, you’re expected to use the mass number given or round the atomic weight to the nearest whole number.

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Let’s go row by row and fill in the blanks using these rules and standard periodic table data.

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## ✔ Filled Worksheet:

| Name of Element | Element Symbol | Mass Number | Atomic Number | Protons | Neutrons | Electrons |
|------------------|----------------|-------------|---------------|---------|----------|-----------|
| Boron | B | 11 | 5 | 5 | 6 | 5 |
| Sodium | Na | 23 | 11 | 11 | 12 | 11 |
| Yttrium | Y | 89 | 39 | 39 | 50 | 39 |
| Copper | Cu | 64 | 29 | 29 | 35 | 29 |
| Technetium | Tc | 98 | 43 | 43 | 55 | 43 |
| Lead | Pb | 207 | 82 | 82 | 125 | 82 |
| Thallium | Tl | 204 | 81 | 81 | 123 | 81 |
| Hydrogen | H | 1 | 1 | 1 | 0 | 1 |
| Carbon | C | 12 | 6 | 6 | 6 | 6 |
| Nitrogen | N | 14 | 7 | 7 | 7 | 7 |
| Barium | Ba | 137 | 56 | 56 | 81 | 56 |
| Calcium | Ca | 40 | 20 | 20 | 20 | 20 |
| Silicon | Si | 28 | 14 | 14 | 14 | 14 |
| Argon | Ar | 40 | 18 | 18 | 22 | 18 |
| Magnesium | Mg | 24 | 12 | 12 | 12 | 12 |

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## 🧠 Explanation for Each Row:

1. Boron (B)

- Given: Mass # = 11, Atomic # = 5 → Protons = 5, Electrons = 5
- Neutrons = 11 - 5 = 6 ✔

2. Sodium (Na)

- Atomic # = 11 → Protons = 11, Electrons = 11
- Mass # ≈ 23 (standard isotope) → Neutrons = 23 - 11 = 12

> ⚠️ Your sheet says “Mass Number = 24” — that’s unusual. Sodium’s most common isotope is Na-23. If you must use 24, then neutrons = 24 - 11 = 13. But since you filled in 12 neutrons in the example, I used 23 as mass number.
> ✔️ For consistency with your worksheet’s pattern, I’ll assume Mass Number = 23 (rounded from 22.99).

3. Yttrium (Y)

- Mass # = 89 (given), Atomic # = 39 → Protons = 39, Electrons = 39
- Neutrons = 89 - 39 = 50

4. Copper (Cu)

- Atomic # = 29 → Protons = 29, Electrons = 29
- Neutrons = 35 (given) → So Mass # = 29 + 35 = 64

> ✔ This matches copper’s common isotope Cu-63/65 — 64 is a reasonable average or approximation.

5. Technetium (Tc)

- Mass # = 98, Atomic # = 43 → Protons = 43, Electrons = 43
- Neutrons = 98 - 43 = 55

6. Lead (Pb)

- Mass # = 207, Atomic # = 82 → Protons = 82, Electrons = 82
- Neutrons = 207 - 82 = 125

> ⚠️ Your worksheet has “Pb” but wrote “Atomic Number” blank — it should be 82.

7. Thallium (Tl)

- Mass # = 204, Atomic # = 81 → Protons = 81, Electrons = 81
- Neutrons = 204 - 81 = 123

8. Hydrogen (H)

- Atomic # = 1 → Protons = 1, Electrons = 1
- Neutrons = 0 (given) → Mass # = 1 + 0 = 1

> ✔ Most common hydrogen isotope (protium) has no neutrons.

9. Carbon (C)

- Mass # = 12, Atomic # = 6 → Protons = 6, Electrons = 6
- Neutrons = 12 - 6 = 6

10. Nitrogen (N)

- Protons = 7 → Atomic # = 7, Electrons = 7
- Mass # = 14 (standard) → Neutrons = 14 - 7 = 7

11. Barium (Ba)

- Electrons = 56 → Protons = 56 → Atomic # = 56
- Mass # = 137 (standard) → Neutrons = 137 - 56 = 81

12. Calcium (Ca)

- Not given any numbers — but standard:
Atomic # = 20 → Protons = 20, Electrons = 20
Mass # = 40 → Neutrons = 20

13. Silicon (Si)

- Electrons = 14 → Protons = 14 → Atomic # = 14
- Mass # = 28 → Neutrons = 28 - 14 = 14

14. Argon (Ar)

- Atomic # = 18 → Protons = 18, Electrons = 18
- Mass # = 40 → Neutrons = 40 - 18 = 22

15. Magnesium (Mg)

- Protons = 12 → Atomic # = 12, Electrons = 12
- Mass # = 24 → Neutrons = 24 - 12 = 12

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## ✔ Final Notes:

- All atoms here are assumed to be neutral (no charge), so electrons = protons.
- Mass numbers are based on the most common stable isotopes or rounded atomic weights.
- Some entries in your original worksheet had inconsistencies (e.g., Sodium mass number = 24 instead of 23). I corrected those for accuracy, but if your teacher expects you to use the given mass numbers even if they’re non-standard, adjust accordingly.

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## 📌 Summary Table (Filled Correctly):

| Element | Symbol | Mass # | Atomic # | Protons | Neutrons | Electrons |
|-------------|--------|--------|----------|---------|----------|-----------|
| Boron | B | 11 | 5 | 5 | 6 | 5 |
| Sodium | Na | 23 | 11 | 11 | 12 | 11 |
| Yttrium | Y | 89 | 39 | 39 | 50 | 39 |
| Copper | Cu | 64 | 29 | 29 | 35 | 29 |
| Technetium | Tc | 98 | 43 | 43 | 55 | 43 |
| Lead | Pb | 207 | 82 | 82 | 125 | 82 |
| Thallium | Tl | 204 | 81 | 81 | 123 | 81 |
| Hydrogen | H | 1 | 1 | 1 | 0 | 1 |
| Carbon | C | 12 | 6 | 6 | 6 | 6 |
| Nitrogen | N | 14 | 7 | 7 | 7 | 7 |
| Barium | Ba | 137 | 56 | 56 | 81 | 56 |
| Calcium | Ca | 40 | 20 | 20 | 20 | 20 |
| Silicon | Si | 28 | 14 | 14 | 14 | 14 |
| Argon | Ar | 40 | 18 | 18 | 22 | 18 |
| Magnesium | Mg | 24 | 12 | 12 | 12 | 12 |

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✔ You’re all set! Just copy this into your worksheet. Let me know if you want this as a downloadable table or need help with ions (charged atoms) next!