1. CF₄:
- Carbon (C) has 4 valence electrons.
- Each fluorine (F) has 7 valence electrons; 4 F atoms × 7 = 28.
- Total valence electrons = 4 + 28 = 32.
- Carbon is central atom, bonded to each F with a single bond (4 bonds × 2 electrons = 8 electrons used).
- Remaining 24 electrons are placed as 3 lone pairs on each F atom.
- All atoms have complete octets.
2. CH₄:
- Carbon (C) has 4 valence electrons.
- Each hydrogen (H) has 1 valence electron; 4 H atoms × 1 = 4.
- Total valence electrons = 4 + 4 = 8.
- Carbon is central atom, bonded to each H with a single bond (4 bonds × 2 electrons = 8 electrons used).
- No lone pairs remain; all electrons are in bonds.
- Carbon has 8 electrons (octet), each H has 2 electrons (duet).
3. CH₃F:
- Carbon (C) has 4 valence electrons.
- Three hydrogens contribute 3 × 1 = 3 electrons.
- Fluorine contributes 7 valence electrons.
- Total valence electrons = 4 + 3 + 7 = 14.
- Carbon is central atom, bonded to three H and one F with single bonds (4 bonds × 2 = 8 electrons used).
- Remaining 6 electrons are placed as 3 lone pairs on F.
- All atoms satisfy octet/duet rules.
4. CH₂F₂:
- Carbon (C) has 4 valence electrons.
- Two hydrogens contribute 2 × 1 = 2 electrons.
- Two fluorines contribute 2 × 7 = 14 electrons.
- Total valence electrons = 4 + 2 + 14 = 20.
- Carbon is central atom, bonded to two H and two F with single bonds (4 bonds × 2 = 8 electrons used).
- Remaining 12 electrons are placed as 3 lone pairs on each F atom.
- All atoms satisfy octet/duet rules.
Parent Tip: Review the logic above to help your child master the concept of lewis structure practice worksheet.
