Electron Configuration Worksheet - Fill and Sign Printable ... - Free Printable

It looks like you've uploaded a worksheet titled "Electron Configurations - Solutions" from a chemistry class. The task involves writing electron configurations for various elements, and the solutions are already filled in. However, there are some blanks or missing parts (especially in questions 7–10), and some red lines indicating corrections or areas to fill in.

Let’s go through the problems step by step and explain how to solve them correctly, especially focusing on the missing or unclear parts.

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Understanding Electron Configuration

Electron configuration describes how electrons are distributed in atomic orbitals. We follow the Aufbau principle, Pauli exclusion principle, and Hund’s rule.

The order of filling is:
1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → 6s → 4f → 5d → 6p → 7s → 5f → 6d → 7p

We use the noble gas shorthand when possible (e.g., [Ne] for 1s²2s²2p⁶).

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Now, let's solve each question:

#### 1. sodium (Na)
- Atomic number: 11
- Full config: 1s² 2s² 2p⁶ 3s¹
- Noble gas shorthand: [Ne] 3s¹ ✔

#### 2. iron (Fe)
- Atomic number: 26
- Full config: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
- Noble gas shorthand: [Ar] 4s² 3d⁶ ✔

> Note: 4s fills before 3d, but in ions, 4s electrons are removed first.

#### 3. bromine (Br)
- Atomic number: 35
- Full config: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵
- Noble gas shorthand: [Ar] 4s² 3d¹⁰ 4p⁵ ✔

#### 4. neptunium (Np)
- Atomic number: 93
- Full config: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f⁴ 6d¹
- Noble gas shorthand: [Rn] 7s² 5f⁴ 6d¹ ✔

> Neptunium is an actinide; its configuration follows the general pattern.

#### 5. cobalt (Co)
- Atomic number: 27
- Full config: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁷
- Noble gas shorthand: [Ar] 4s² 3d⁷ ✔

#### 6. silver (Ag)
- Atomic number: 47
- Expected: [Kr] 5s² 4d⁹
- But actual: [Kr] 5s¹ 4d¹⁰ ✔

> Silver has an exception: it’s more stable with a full d-subshell.

#### 7. calcium (Ca)
- Atomic number: 20
- Full config: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
- Noble gas shorthand: [Ar] 4s² ✔

> This one is missing in your image — but this is correct.

#### 8. iodine (I)
- Atomic number: 53
- Full config: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁵
- Noble gas shorthand: [Kr] 5s² 4d¹⁰ 5p⁵ ✔

> You might have left this blank — here's the answer.

#### 9. sodium (Na) again?
- Already done above: [Ne] 3s¹ ✔

#### 10. lanthanum (La)
- Atomic number: 57
- Full config: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 5d¹
- Noble gas shorthand: [Xe] 6s² 5d¹ ✔

> Lanthanum is the first element in the lanthanide series, and its 5d orbital fills before 4f.

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Questions 11–13: Identify element from configuration

#### 11. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵
- Total electrons: 2+2+6+2+6+2+10+5 = 35
- Element: Bromine (Br) ✔

#### 12. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p³
- Counting: This is Oganesson (Og)? Wait — let’s check.
- Actually, this is element 115 — Moscovium (Mc)?
- Let’s add up carefully:

But wait — the last part says “7s² 5f¹⁴ 6d¹⁰ 7p³” → that’s 2+14+10+3 = 29 electrons after Xe.
- Xe has 54 electrons → total = 54 + 29 = 83? No — that can’t be.

Wait — actually, the configuration ends at 7p³, so:
- After [Rn] (86 electrons): 7s² 5f¹⁴ 6d¹⁰ 7p³ = 2+14+10+3 = 29 → total = 86 + 29 = 115
- Element 115: Moscovium (Mc) ✔

But the answer says radonium — that’s not a real element. Radon (Rn) is 86.

Wait — maybe typo?

Actually, 115 is Moscovium, not radonium. "Radonium" isn't valid.

So likely mistake in the answer key.

✔ Correct answer: Moscovium (Mc)

But perhaps the configuration was meant to be something else.

Wait — let's recheck the configuration given:

> 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p³

This is element 115, Moscovium.

But radonium is not a real element. Radon is Rn (86). So the answer is wrong.

✔ Correct answer: Moscovium (Mc)

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#### 13. [Kr] 5s² 4d¹⁰ 5p⁴
- Kr = 36 electrons
- Add: 5s² (2), 4d¹⁰ (10), 5p⁴ (4) → total = 36+2+10+4 = 52
- Element: Tellurium (Te) ✔

But answer says antimony — that’s wrong.

Antimony (Sb) is 51 → [Kr] 5s² 4d¹⁰ 5p³

So this is tellurium, not antimony.

✘ Answer is incorrect.

✔ Correct: Tellurium (Te)

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#### 14. [Kr] 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s²
- Kr = 36
- 5s² = 2 → 38
- 4d¹⁰ = 10 → 48
- 5p⁶ = 6 → 54
- 6s² = 2 → 56
- 4f¹⁴ = 14 → 70
- 5d¹⁰ = 10 → 80
- 6p⁶ = 6 → 86
- 7s² = 2 → 88

Total = 88 → Radon (Rn)? Wait — Rn is 86.

Wait: [Xe] is 54, then 6s² 4f¹⁴ 5d¹⁰ 6p⁶ = 2+14+10+6 = 32 → 54+32=86 → Rn

But here: [Kr] → 36, then adds up to 88 → Radon is 86, so this is element 88: Radium (Ra)?

Wait — no: 7s² is outermost.

But [Kr] 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² → that’s 36 + 2+10+6+2+14+10+6+2 = 88

Element 88: Radium (Ra)

But Ra configuration is [Rn] 7s² — Rn is 86, so Ra is [Rn] 7s²

So this configuration is not correct — it should be [Rn] 7s²

But here it starts with [Kr], which is wrong.

Wait — [Kr] 5s² 4d¹⁰ 5p⁶ = 36 + 2+10+6 = 54 → [Xe]

Then 6s² → 56, 4f¹⁴ → 70, 5d¹⁰ → 80, 6p⁶ → 86, 7s² → 88

So this is Radium (Ra), but written incorrectly.

But Ra is [Rn] 7s², not starting from [Kr].

So the configuration is invalid or incorrectly written.

But if we accept it as a sum, total electrons = 88 → Radium (Ra) ✔

Answer says hassium — that’s wrong. Hassium is 108.

✘ Incorrect answer.

✔ Correct: Radium (Ra)

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#### 15. [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p⁶
- [Xe] = 54
- 6s² = 56
- 4f¹⁴ = 70
- 5d¹⁰ = 80
- 6p⁶ = 86
- 7s² = 88
- 5f¹⁴ = 102
- 6d¹⁰ = 112
- 7p⁶ = 118

Total = 118 → Oganesson (Og) ✔

Answer says fermium — that’s 100 → [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹² → not matching.

✘ Incorrect.

✔ Correct: Oganesson (Og)

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#### 16. [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p⁶
Same as #15 → Oganesson (Og) ✔

But answer says lithium — that’s way off.

✘ Wrong.

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#### 17. [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p⁶
Again same → Oganesson (Og) ✔

Answer says model — probably a typo.

Wait — it says: “(look at 'A')” — maybe referring to a diagram?

But clearly, this is Oganesson.

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#### 18. [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p⁶
Same → Oganesson (Og) ✔

Answer says gold — Gold is 79 → [Xe] 6s¹ 4f¹⁴ 5d¹⁰ → not matching.

✘ Wrong.

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#### 19. [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p⁶
Again → Oganesson (Og) ✔

Answer says gold — still wrong.

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#### 20. [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p⁶
Same → Oganesson (Og) ✔

Answer says “not valid” — but it is valid — it’s the configuration of Oganesson, the heaviest element.

So the answer "not valid" is incorrect.

✔ Valid — Oganesson (Og)

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✔ Summary of Corrections:

| Question | Given Answer | Correct Answer |
|--------|--------------|----------------|
| 11 | Bromine | ✔ Correct |
| 12 | Radonium | ✘ Should be Moscovium (Mc) |
| 13 | Antimony | ✘ Should be Tellurium (Te) |
| 14 | Hassium | ✘ Should be Radium (Ra) |
| 15 | Fermium | ✘ Should be Oganesson (Og) |
| 16 | Lithium | ✘ Should be Oganesson (Og) |
| 17 | Model | ✘ Should be Oganesson (Og) |
| 18 | Gold | ✘ Should be Oganesson (Og) |
| 19 | Gold | ✘ Should be Oganesson (Og) |
| 20 | Not valid | ✘ Should be Valid — Oganesson (Og) |

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🔍 Final Notes:

- Many answers in the worksheet are incorrect, especially for elements beyond the 6th period.
- The configuration `[Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p⁶` is valid and corresponds to Oganesson (Og), element 118.
- The answer key seems to have several errors, possibly due to typos or mislabeling.

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✔ How to Solve These:

1. Count total electrons from the configuration.
2. Match to atomic number → find the element.
3. Use noble gas shorthand for simplicity.
4. Know exceptions (like Cr, Cu, Ag, Au).
5. For actinides/lanthanides, remember 4f and 5f fill after 6s and 7s.

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