Atoms Family Atomic Math Challenge - Free Printable

Let’s go step by step to make sure we understand how to fill out each part of the worksheet correctly.

We’re working with atoms and their basic properties: atomic number, atomic mass, protons, neutrons, and electrons.

Here’s what you need to know:

- Atomic Number = number of protons (and also electrons in a neutral atom)
- Atomic Mass ≈ protons + neutrons (we round it to the nearest whole number for this worksheet)
- So, Neutrons = Atomic Mass (rounded) – Atomic Number

Now let’s check each element one by one.

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1. Oxygen (O)
Given:
Atomic # = 8 → so protons = 8, electrons = 8
Atomic Mass = 15.999 → round to 16
Neutrons = 16 – 8 = 8 ✔
Your answers are correct.

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2. Zinc (Zn)
Given:
Atomic # = 30 → protons = 30, electrons = 30
Atomic Mass = 65.39 → round to 65? Wait — you wrote 105. That’s not right.

Wait — hold on! The atomic mass given is 65.39, which rounds to 65, not 105.

So:
- Atomic Mass should be 65
- Neutrons = 65 – 30 = 35 → that part is correct if mass was 65
But you wrote Atomic Mass = 105 — that’s wrong.

Actually, looking again — maybe you misread the box? The box says “65.39” under Zinc. So atomic mass is ~65.

BUT — wait! In your answer, you have:

> Atomic Mass = 105
> # of Neutrons = 35

If neutrons = 35 and protons = 30, then mass = 65 — so why did you write 105?

That must be a mistake. Let me double-check the image...

Looking at the image: Under Zinc, it says “65.39” — so atomic mass is 65.

You probably meant to write 65, but accidentally wrote 105. Because 30 + 35 = 65.

So correction:
→ Atomic Mass = 65 (not 105)
→ Neutrons = 35 ✔
→ Everything else is fine.

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3. Lithium (Li)
Atomic # = 3 → protons = 3, electrons = 3
Atomic Mass = 6.941 → round to 7
Neutrons = 7 – 3 = 4 ✔
All correct.

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4. Silicon (Si)
Atomic # = 14 → protons = 14, electrons = 14
Atomic Mass = 28.086 → round to 28
Neutrons = 28 – 14 = 14 ✔
Correct.

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5. Boron (B)
Atomic # = 5 → protons = 5, electrons = 5
Atomic Mass = 10.81 → round to 11
Neutrons = 11 – 5 = 6 ✔
Correct.

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6. Bromine (Br)
Atomic # = 35 → protons = 35, electrons = 35
Atomic Mass = 79.904 → round to 80
Neutrons = 80 – 35 = 45 ✔
Correct.

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Only error found:
In Zinc section, you wrote Atomic Mass = 105, but it should be 65.

Everything else matches perfectly.

Final Answer:
The only correction needed is for Zinc: Atomic Mass should be 65, not 105. All other values are correct.