Free Printable Protons Neutrons and Electrons Practice Worksheets - Free Printable

Let's solve this step-by-step.

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Part 1: Fill in the element name and the number of protons and neutrons

We are given isotopic notations in the form:

\[
^A_ZX
\]

Where:
- \( A \) = mass number (protons + neutrons)
- \( Z \) = atomic number (number of protons)
- \( X \) = chemical symbol

Number of protons = atomic number (Z)
Number of neutrons = mass number (A) – atomic number (Z)

---

#### 1. \( ^4_2He \)

- Element name: Helium
- # of protons: 2
- # of neutrons: \( 4 - 2 = 2 \)

#### 2. \( ^{56}_{26}Fe \)

- Element name: Iron
- # of protons: 26
- # of neutrons: \( 56 - 26 = 30 \)

#### 3. \( ^{27}_{13}Al \)

- Element name: Aluminum
- # of protons: 13
- # of neutrons: \( 27 - 13 = 14 \)

#### 4. \( ^{40}_{20}Ca \)

- Element name: Calcium
- # of protons: 20
- # of neutrons: \( 40 - 20 = 20 \)

#### 5. \( ^{56}_{26}Ne \)

Wait! This is a mistake. Neon (Ne) has atomic number 10, not 26. The notation \( ^{56}_{26}Ne \) is incorrect.

But let’s double-check:
The symbol is \( ^{56}_{26}Ne \). But Neon has atomic number 10, so it can't have 26 protons. This must be a typo.

Looking at the notation, \( ^{56}_{26} \) corresponds to Iron (Fe), which we already did.

So likely, this should be \( ^{20}_{10}Ne \), but it says \( ^{56}_{26}Ne \), which is impossible.

Wait — perhaps it's a typo in the problem? Let's check the actual symbol.

But the symbol is written as Ne, which is neon. So if it's really \( ^{56}_{26}Ne \), that's invalid.

Alternatively, maybe it's meant to be \( ^{20}_{10}Ne \)? But the mass number is written as 56.

Wait — another possibility: maybe it's \( ^{20}_{10}Ne \), but printed incorrectly?

But looking again: the problem says:

> \( ^{56}_{26}Ne \)

That cannot be correct. Neon has atomic number 10, so Z=10, not 26.

This appears to be a typo. It should probably be \( ^{20}_{10}Ne \) or \( ^{56}_{26}Fe \), but Fe was already listed.

Wait — actually, in the list, \( ^{56}_{26}Fe \) is already there, and then \( ^{56}_{26}Ne \) is next — that's clearly wrong.

So likely, the second one is supposed to be \( ^{20}_{10}Ne \), or maybe it's a different element.

But the symbol is Ne, so we must assume it's neon.

Therefore, this notation is incorrect. But for the sake of solving, let’s suppose it's a typo and it's meant to be \( ^{20}_{10}Ne \).

But wait — the mass number is 56, and atomic number 26 — that’s iron, not neon.

So \( ^{56}_{26}Ne \) is invalid.

Alternatively, perhaps it's a misprint and it should be \( ^{20}_{10}Ne \), but that would make the mass number 20.

But it says 56.

Another idea: maybe it's \( ^{20}_{10}Ne \), and the 56 is a typo?

But no — the image shows \( ^{56}_{26}Ne \)

This is inconsistent.

Wait — perhaps it's \( ^{20}_{10}Ne \), but someone wrote 56 by mistake?

But let's look at the other entries.

Wait — maybe it's not a typo? Let's check what element has atomic number 26 — it's Iron (Fe), and mass number 56 — that's common iron.

So \( ^{56}_{26}Fe \) is correct.

Then why is \( ^{56}_{26}Ne \) written?

Possibly a mistake in the worksheet.

But let's proceed carefully.

Perhaps it's \( ^{20}_{10}Ne \) with mass number 20, not 56.

But the problem says \( ^{56}_{26}Ne \), which is physically impossible.

So I will assume it's a typo and it should be \( ^{20}_{10}Ne \), or perhaps it's meant to be something else.

But since the symbol is Ne, and atomic number is 26, it's invalid.

Alternatively, maybe it's \( ^{20}_{10}Ne \), and the numbers were swapped?

No — the notation is standard: top is mass, bottom is atomic number.

So \( ^{56}_{26}Ne \) implies 26 protons → element is Fe, but symbol is Ne → contradiction.

Therefore, this is an error.

But let's look at the rest.

Wait — maybe it's \( ^{20}_{10}Ne \) and the "56" is a typo.

But the image shows \( ^{56}_{26}Ne \)

Alternatively, maybe it's \( ^{20}_{10}Ne \), and the "56" is meant to be "20", and "26" is "10"?

But it's written as 56 and 26.

I think this is a typo in the worksheet.

Given that, let’s skip it for now and come back.

But let's check the third one in the second row: \( ^{12}_{6}Ca \)

Calcium has atomic number 20, not 6. So \( ^{12}_{6}Ca \) is also invalid.

Because atomic number 6 is carbon.

So \( ^{12}_{6}C \) is carbon-12.

But here it's labeled as Ca — calcium.

So this is also a typo.

Similarly, \( ^{12}_{6}Ca \) should be \( ^{12}_{6}C \) or \( ^{40}_{20}Ca \)

But earlier we have \( ^{40}_{20}Ca \), so this one is likely meant to be \( ^{12}_{6}C \)

But it's written as Ca.

So multiple typos.

Let me re-express the elements:

List:

1. \( ^4_2He \) → He, 2p, 2n ✔
2. \( ^{56}_{26}Fe \) → Fe, 26p, 30n ✔
3. \( ^{27}_{13}Al \) → Al, 13p, 14n ✔
4. \( ^{40}_{20}Ca \) → Ca, 20p, 20n ✔
5. \( ^{56}_{26}Ne \) → ✘ Invalid — should be Fe or Ne with correct Z
6. \( ^{12}_{6}Ca \) → ✘ Invalid — should be C or Ca with correct Z
7. \( ^{19}_9F \) → F, 9p, 10n ✔
8. \( ^{35}_{17}Cl \) → Cl, 17p, 18n ✔
9. \( ^{23}_{11}Na \) → Na, 11p, 12n ✔

So the problematic ones are:

- \( ^{56}_{26}Ne \): Should be \( ^{56}_{26}Fe \) or \( ^{20}_{10}Ne \)
- \( ^{12}_{6}Ca \): Should be \( ^{12}_{6}C \) or \( ^{40}_{20}Ca \)

But since \( ^{56}_{26}Fe \) is already listed, and \( ^{40}_{20}Ca \) is also listed, these two must be typos.

So likely:

- \( ^{56}_{26}Ne \) → probably meant to be \( ^{20}_{10}Ne \) (neon-20)
- \( ^{12}_{6}Ca \) → probably meant to be \( ^{12}_{6}C \) (carbon-12)

But the symbols are written as Ne and Ca, so perhaps the symbols are wrong.

Alternatively, maybe the numbers are wrong.

But based on the context, let's assume:

- \( ^{56}_{26}Ne \) → typo: should be \( ^{20}_{10}Ne \)
- \( ^{12}_{6}Ca \) → typo: should be \( ^{12}_{6}C \)

But since the worksheet says Ne and Ca, we'll go with what's written, but note the inconsistencies.

Alternatively, perhaps it's:

- \( ^{56}_{26}Ne \) → but Ne has Z=10, so it's invalid.
- \( ^{12}_{6}Ca \) → Ca has Z=20, so invalid.

So both are errors.

But for the sake of completing the exercise, let's assume:

- \( ^{56}_{26}Ne \) → is a typo and should be \( ^{20}_{10}Ne \)
- \( ^{12}_{6}Ca \) → is a typo and should be \( ^{12}_{6}C \)

But the instructions say to fill in based on the given symbols.

So perhaps the symbols are correct, and the numbers are wrong?

No — the notation is standard.

So I think the best approach is to ignore the symbol if it contradicts the atomic number, and use the atomic number to determine the element.

But the symbol is part of the notation.

Let’s proceed with the correct interpretation:

For each, use the atomic number (bottom number) to determine the element name.

Even if the symbol doesn’t match, the atomic number defines the element.

So:

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Correcting based on atomic number:

#### 1. \( ^4_2He \)

- Atomic number = 2 → Helium
- Protons: 2
- Neutrons: 4 - 2 = 2

✔

#### 2. \( ^{56}_{26}Fe \)

- Z = 26 → Iron
- Protons: 26
- Neutrons: 56 - 26 = 30

✔

#### 3. \( ^{27}_{13}Al \)

- Z = 13 → Aluminum
- Protons: 13
- Neutrons: 27 - 13 = 14

✔

#### 4. \( ^{40}_{20}Ca \)

- Z = 20 → Calcium
- Protons: 20
- Neutrons: 40 - 20 = 20

✔

#### 5. \( ^{56}_{26}Ne \)

- Z = 26 → Iron (not Neon!)
- But symbol is Ne → inconsistency
- So either symbol is wrong or atomic number is wrong
- Since Z=26, element is Iron
- Protons: 26
- Neutrons: 56 - 26 = 30
- But symbol is Ne → error

So likely, symbol should be Fe, not Ne.

But since it's written as Ne, perhaps it's a typo.

We’ll write Iron as element name, despite symbol.

Or maybe the atomic number is wrong.

But 56/26 is iron.

So we’ll go with:

- Element name: Iron (despite symbol Ne)
- Protons: 26
- Neutrons: 30

But that’s redundant with the first Fe.

Alternatively, perhaps it's meant to be \( ^{20}_{10}Ne \), so:

- Mass = 20, Z = 10 → Neon
- But it's written as 56 and 26 — so not.

So I think it's a typo.

But for the purpose of answering, we'll assume the atomic number is correct, so:

- Element name: Iron (because Z=26)
- Protons: 26
- Neutrons: 30

Even though symbol is Ne, we ignore symbol for element name.

Similarly:

#### 6. \( ^{12}_{6}Ca \)

- Z = 6 → Carbon
- But symbol is Ca → Calcium (Z=20) → contradiction
- So element name: Carbon
- Protons: 6
- Neutrons: 12 - 6 = 6

So even though it says Ca, Z=6 means Carbon.

So we'll use atomic number.

#### 7. \( ^{19}_9F \)

- Z = 9 → Fluorine
- Protons: 9
- Neutrons: 19 - 9 = 10

✔

#### 8. \( ^{35}_{17}Cl \)

- Z = 17 → Chlorine
- Protons: 17
- Neutrons: 35 - 17 = 18

✔

#### 9. \( ^{23}_{11}Na \)

- Z = 11 → Sodium
- Protons: 11
- Neutrons: 23 - 11 = 12

✔

So final answers for Part 1:

| Symbol | Element Name | Protons | Neutrons |
|--------|--------------|---------|----------|
| \( ^4_2He \) | Helium | 2 | 2 |
| \( ^{56}_{26}Fe \) | Iron | 26 | 30 |
| \( ^{27}_{13}Al \) | Aluminum | 13 | 14 |
| \( ^{40}_{20}Ca \) | Calcium | 20 | 20 |
| \( ^{56}_{26}Ne \) | Iron (should be Fe) | 26 | 30 |
| \( ^{12}_{6}Ca \) | Carbon (should be C) | 6 | 6 |
| \( ^{19}_9F \) | Fluorine | 9 | 10 |
| \( ^{35}_{17}Cl \) | Chlorine | 17 | 18 |
| \( ^{23}_{11}Na \) | Sodium | 11 | 12 |

But since the worksheet has the symbols, and they don't match, we’ll write the element name based on atomic number.

So for \( ^{56}_{26}Ne \): Element name: Iron
For \( ^{12}_{6}Ca \): Element name: Carbon

Even though symbols are wrong.

Now, Part 2.

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Part 2: Using periodic table, fill in missing information

We are given a table:

| Element | Atomic Number | Atomic Mass | # protons | # neutrons | # electrons |
|--------|---------------|-------------|-----------|------------|-------------|
| S | 16 | ? | 16 | ? | ? |
| ? | 17 | 35 | ? | ? | 17 |
| ? | 18 | ? | 18 | 22 | ? |
| ? | 19 | 39 | ? | ? | 19 |
| Ca | 20 | ? | 20 | ? | ? |

We need to fill in the blanks.

Recall:
- Atomic number = number of protons = number of electrons (in neutral atom)
- Atomic mass ≈ protons + neutrons
- So neutrons = atomic mass - protons

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#### Row 1: S (Sulfur)
- Atomic number = 16 → protons = 16
- Electrons = 16 (neutral atom)
- Atomic mass: from periodic table, sulfur has atomic mass ≈ 32.07, so we use 32
- Neutrons = 32 - 16 = 16

So:
- Atomic Mass: 32
- Neutrons: 16
- Electrons: 16

#### Row 2: Atomic number = 17, mass = 35, electrons = 17
- Element: Atomic number 17 → Chlorine (Cl)
- Protons = 17
- Neutrons = 35 - 17 = 18
- Electrons = 17 (given)

So:
- Element: Cl
- Protons: 17
- Neutrons: 18

#### Row 3: Atomic number = 18, protons = 18, neutrons = 22
- Element: Atomic number 18 → Argon (Ar)
- Atomic mass = protons + neutrons = 18 + 22 = 40
- Electrons = 18 (neutral)

So:
- Element: Ar
- Atomic Mass: 40
- Electrons: 18

#### Row 4: Atomic number = 19, mass = 39, electrons = 19
- Element: Atomic number 19 → Potassium (K)
- Protons = 19
- Neutrons = 39 - 19 = 20

So:
- Element: K
- Protons: 19
- Neutrons: 20

#### Row 5: Ca (Calcium), atomic number = 20, protons = 20
- Atomic mass: from periodic table, calcium ≈ 40.08, so use 40
- Neutrons = 40 - 20 = 20
- Electrons = 20 (neutral)

So:
- Atomic Mass: 40
- Neutrons: 20
- Electrons: 20

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Final Answers:

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Part 1:

1. \( ^4_2He \)
- Element name: Helium
- Protons: 2
- Neutrons: 2

2. \( ^{56}_{26}Fe \)
- Element name: Iron
- Protons: 26
- Neutrons: 30

3. \( ^{27}_{13}Al \)
- Element name: Aluminum
- Protons: 13
- Neutrons: 14

4. \( ^{40}_{20}Ca \)
- Element name: Calcium
- Protons: 20
- Neutrons: 20

5. \( ^{56}_{26}Ne \) → Error: Z=26 → element is Iron, not Neon
- Element name: Iron
- Protons: 26
- Neutrons: 30

6. \( ^{12}_{6}Ca \) → Error: Z=6 → element is Carbon, not Calcium
- Element name: Carbon
- Protons: 6
- Neutrons: 6

7. \( ^{19}_9F \)
- Element name: Fluorine
- Protons: 9
- Neutrons: 10

8. \( ^{35}_{17}Cl \)
- Element name: Chlorine
- Protons: 17
- Neutrons: 18

9. \( ^{23}_{11}Na \)
- Element name: Sodium
- Protons: 11
- Neutrons: 12

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Part 2: Table

| Element | Atomic Number | Atomic Mass | # protons | # neutrons | # electrons |
|--------|---------------|-------------|-----------|------------|-------------|
| S | 16 | 32 | 16 | 16 | 16 |
| Cl | 17 | 35 | 17 | 18 | 17 |
| Ar | 18 | 40 | 18 | 22 | 18 |
| K | 19 | 39 | 19 | 20 | 19 |
| Ca | 20 | 40 | 20 | 20 | 20 |

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Summary of Corrections:

- In Part 1, two entries have incorrect symbols:
- \( ^{56}_{26}Ne \) → should be \( ^{56}_{26}Fe \) (Iron)
- \( ^{12}_{6}Ca \) → should be \( ^{12}_{6}C \) (Carbon)
- But based on atomic number, we used correct element names.

If the worksheet intended those symbols, then it contains errors.

But for educational purposes, we filled in correctly using atomic number.

Let me know if you'd like a corrected version of the worksheet.