Let's solve the problem step by step based on the worksheet titled
"What Are Valence Electrons?"
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🔍 Understanding the Concept:
-
Valence electrons are the outermost electrons in an atom.
- To find the number of valence electrons, look at the
group number of the element in the periodic table (for main group elements).
- Elements in
Groups 1–2 and 13–18 have valence electrons equal to their group number (with a small adjustment for Groups 13–18):
- Group 1 → 1 valence electron
- Group 2 → 2 valence electrons
- Group 13 → 3 valence electrons
- Group 14 → 4 valence electrons
- Group 15 → 5 valence electrons
- Group 16 → 6 valence electrons
- Group 17 → 7 valence electrons
- Group 18 → 8 valence electrons (except helium, which has 2)
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✔ Let’s Solve Each Question:
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1) helium
- Helium is in
Group 18 (noble gases).
- But helium only has
2 electrons, both in the first shell.
- So, it has
2 valence electrons.
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✔ Answer:
2
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2) magnesium
- Magnesium is in
Group 2.
- Group 2 elements have
2 valence electrons.
>
✔ Answer:
2
####
3) sulfur
- Sulfur is in
Group 16.
- Group 16 elements have
6 valence electrons.
>
✔ Answer:
6
####
4) hydrogen
- Hydrogen is in
Group 1.
- It has
1 valence electron.
>
✔ Answer:
1
####
5) krypton
- Krypton is in
Group 18 (noble gas).
- Noble gases have full valence shells →
8 valence electrons (except helium).
>
✔ Answer:
8
####
6) aluminum
- Aluminum is in
Group 13.
- Group 13 elements have
3 valence electrons.
>
✔ Answer:
3
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🧩 Final Answers:
| Element | Valence Electrons |
|------------|-------------------|
| 1) helium |
2 |
| 2) magnesium|
2 |
| 3) sulfur |
6 |
| 4) hydrogen |
1 |
| 5) krypton |
8 |
| 6) aluminum |
3 |
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💡 Additional Notes:
- The
octet rule says atoms want 8 valence electrons to be stable (except H and He, which follow the
duet rule – need 2 electrons).
- This is why helium (2 electrons) is stable, even though it's in Group 18.
✔ All answers are consistent with periodic table trends and valence electron rules.
Parent Tip: Review the logic above to help your child master the concept of valence electron worksheet.
