Let’s work through each element one by one.
We need to find:
1. The number of valence electrons (for Lewis structure).
2. The total number of electrons (for Bohr model — which equals atomic number for neutral atoms).
Then we’ll describe how to draw the Lewis dot and Bohr model based on that.
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Lithium (Li)
- Atomic number = 3 → Total electrons = 3
- Electron configuration: 2 in first shell, 1 in second → Valence electrons = 1
→ Lewis structure: One dot around Li symbol
→ Bohr model: Nucleus with 3 e⁻; inner ring has 2 e⁻, outer ring has 1 e⁻
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Helium (He)
- Atomic number = 2 → Total electrons = 2
- Both electrons are in first shell → Valence electrons = 2 (full shell)
→ Lewis structure: Two dots around He (usually paired)
→ Bohr model: Nucleus with 2 e⁻; only one ring with 2 e⁻
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Sodium (Na)
- Atomic number = 11 → Total electrons = 11
- Configuration: 2, 8, 1 → Valence electrons = 1
→ Lewis structure: One dot around Na
→ Bohr model: Nucleus with 11 e⁻; rings: 2, then 8, then 1
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Calcium (Ca)
- Atomic number = 20 → Total electrons = 20
- Configuration: 2, 8, 8, 2 → Valence electrons = 2
→ Lewis structure: Two dots around Ca
→ Bohr model: Nucleus with 20 e⁻; rings: 2, 8, 8, 2
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Silicon (Si)
- Atomic number = 14 → Total electrons = 14
- Configuration: 2, 8, 4 → Valence electrons = 4
→ Lewis structure: Four dots around Si (one on each side, or two pairs)
→ Bohr model: Nucleus with 14 e⁻; rings: 2, 8, 4
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Argon (Ar)
- Atomic number = 18 → Total electrons = 18
- Configuration: 2, 8, 8 → Valence electrons = 8 (full octet)
→ Lewis structure: Eight dots around Ar (four sides, two per side)
→ Bohr model: Nucleus with 18 e⁻; rings: 2, 8, 8
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Now let’s fill in the blanks as requested:
For each box:
Lithium
# of valence e⁻:
1
# of e⁻:
3
Helium
# of valence e⁻:
2
# of e⁻:
2
Sodium
# of valence e⁻:
1
# of e⁻:
11
Calcium
# of valence e⁻:
2
# of e⁻:
20
Silicon
# of valence e⁻:
4
# of e⁻:
14
Argon
# of valence e⁻:
8
# of e⁻:
18
Final Answer:
Lithium: valence e⁻ = 1, total e⁻ = 3
Helium: valence e⁻ = 2, total e⁻ = 2
Sodium: valence e⁻ = 1, total e⁻ = 11
Calcium: valence e⁻ = 2, total e⁻ = 20
Silicon: valence e⁻ = 4, total e⁻ = 14
Argon: valence e⁻ = 8, total e⁻ = 18
Parent Tip: Review the logic above to help your child master the concept of atomic diagrams worksheet.
