Atomic Math online exercise for - Free Printable

Absolutely! Let’s break this down step by step.

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## 🔬 PART 1: Labeling the Element Square (Oxygen Example)

You’re given an element square for Oxygen (O):

```
8
O
Oxygen
15.999
```

➤ Top Number (8):

> “This is the number of _______ in the atom. (It’s also the number of electrons, unless the atom is an ION)”

✔ Answer: Protons

Explanation: The top number is the Atomic Number. It tells you the number of protons in the nucleus of the atom. In a neutral atom (not an ion), the number of electrons equals the number of protons — so it’s also the number of electrons.

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➤ Bottom Number (15.999):

> “This is the number of protons and neutrons combined. To get the number of neutrons you need to _______ the Atomic # from this number. (Round the mass to the nearest whole number first)”

✔ Answer: Subtract

Explanation: The bottom number is the Atomic Mass (or atomic weight). It’s approximately the sum of protons + neutrons (since electrons have negligible mass). To find the number of neutrons, you:

1. Round the atomic mass to the nearest whole number → 15.999 ≈ 16
2. Subtract the atomic number (protons) → 16 – 8 = 8 neutrons

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## ✏️ PART 2: Complete the Examples

We’ll use the same logic for each element.

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🧪 EXAMPLE 1: Lithium (Li) — Already Done (for reference)

- Atomic # = 3
- Atomic Mass = 6.941 → rounds to 7
- # of Protons = 3
- # of Neutrons = 7 – 3 = 4
- # of Electrons = 3 (neutral atom)

---

🧪 EXAMPLE 2: Boron (B)

```
5
B
______
10.81
```

- Atomic # = 5
- Atomic Mass = 10.81
- # of Protons = 5
- # of Neutrons = Round 10.81 → 11 → 11 – 5 = 6
- # of Electrons = 5

✔ Fill in:
- Atomic # = 5
- Atomic Mass = 10.81
- # of Protons = 5
- # of Neutrons = 6
- # of Electrons = 5

---

🧪 EXAMPLE 3: Oxygen (O)

```
8
O
______
15.999
```

- Atomic # = 8
- Atomic Mass = 15.999
- # of Protons = 8
- # of Neutrons = Round 15.999 → 16 → 16 – 8 = 8
- # of Electrons = 8

✔ Fill in:
- Atomic # = 8
- Atomic Mass = 15.999
- # of Protons = 8
- # of Neutrons = 8
- # of Electrons = 8

---

🧪 EXAMPLE 4: Zinc (Zn)

```
30
__
Zinc
65.39
```

⚠️ Note: The symbol for Zinc is Zn, not written here — but we know it from the name.

- Atomic # = 30
- Atomic Mass = 65.39
- # of Protons = 30
- # of Neutrons = Round 65.39 → 65 → 65 – 30 = 35
- # of Electrons = 30

✔ Fill in:
- Atomic # = 30
- Atomic Mass = 65.39
- # of Protons = 30
- # of Neutrons = 35
- # of Electrons = 30

---

🧪 EXAMPLE 5: Iodine (I)

```
53
__
Iodine
126.905
```

- Atomic # = 53
- Atomic Mass = 126.905
- # of Protons = 53
- # of Neutrons = Round 126.905 → 127 → 127 – 53 = 74
- # of Electrons = 53

✔ Fill in:
- Atomic # = 53
- Atomic Mass = 126.905
- # of Protons = 53
- # of Neutrons = 74
- # of Electrons = 53

---

🧪 EXAMPLE 6: Nitrogen (N)

```
7
N
______
14.077
```

- Atomic # = 7
- Atomic Mass = 14.077
- # of Protons = 7
- # of Neutrons = Round 14.077 → 14 → 14 – 7 = 7
- # of Electrons = 7

✔ Fill in:
- Atomic # = 7
- Atomic Mass = 14.077
- # of Protons = 7
- # of Neutrons = 7
- # of Electrons = 7

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## ✔ FINAL ANSWERS SUMMARY:

Labeling the Oxygen Square:

- Top number (8): Protons
- Bottom number (15.999): You need to subtract the Atomic # from this number to get neutrons.

---

Completed Tables:

#### Boron (B)
- Atomic # = 5
- Atomic Mass = 10.81
- # of Protons = 5
- # of Neutrons = 6
- # of Electrons = 5

#### Oxygen (O)
- Atomic # = 8
- Atomic Mass = 15.999
- # of Protons = 8
- # of Neutrons = 8
- # of Electrons = 8

#### Zinc (Zn)
- Atomic # = 30
- Atomic Mass = 65.39
- # of Protons = 30
- # of Neutrons = 35
- # of Electrons = 30

#### Iodine (I)
- Atomic # = 53
- Atomic Mass = 126.905
- # of Protons = 53
- # of Neutrons = 74
- # of Electrons = 53

#### Nitrogen (N)
- Atomic # = 7
- Atomic Mass = 14.077
- # of Protons = 7
- # of Neutrons = 7
- # of Electrons = 7

---

💡 Quick Tip: Always remember —
🔹 Atomic Number = Protons = Electrons (in neutral atoms)
🔹 Mass Number (rounded) – Atomic Number = Neutrons

Let me know if you’d like this as a printable worksheet or want to check more elements! 🧪📚