1. carbon tetrabromide (CBr₄)
- Carbon (C) has 4 valence electrons.
- Each bromine (Br) has 7 valence electrons; 4 Br atoms = 28 valence electrons.
- Total valence electrons: 4 + 28 = 32.
- Carbon is central, bonded to four bromine atoms with single bonds.
- Each bond uses 2 electrons (8 total for bonds), leaving 24 electrons as lone pairs (6 on each Br).
- Final structure: C in center, single bonds to four Br atoms, each Br with 3 lone pairs.
2. dihydrogen monosulfide (H₂S)
- Hydrogen (H) has 1 valence electron; 2 H atoms = 2 valence electrons.
- Sulfur (S) has 6 valence electrons.
- Total valence electrons: 2 + 6 = 8.
- Sulfur is central, bonded to two hydrogen atoms with single bonds.
- Each bond uses 2 electrons (4 total for bonds), leaving 4 electrons as 2 lone pairs on sulfur.
- Final structure: S in center, single bonds to two H atoms, S with 2 lone pairs.
3. dihydrogen monoselenide (H₂Se)
- Hydrogen (H) has 1 valence electron; 2 H atoms = 2 valence electrons.
- Selenium (Se) has 6 valence electrons.
- Total valence electrons: 2 + 6 = 8.
- Selenium is central, bonded to two hydrogen atoms with single bonds.
- Each bond uses 2 electrons (4 total for bonds), leaving 4 electrons as 2 lone pairs on selenium.
- Final structure: Se in center, single bonds to two H atoms, Se with 2 lone pairs.
4. phosphorus triiodide (PI₃)
- Phosphorus (P) has 5 valence electrons.
- Each iodine (I) has 7 valence electrons; 3 I atoms = 21 valence electrons.
- Total valence electrons: 5 + 21 = 26.
- Phosphorus is central, bonded to three iodine atoms with single bonds.
- Each bond uses 2 electrons (6 total for bonds), leaving 20 electrons as lone pairs (6 on each I and 2 on P).
- Final structure: P in center, single bonds to three I atoms, each I with 3 lone pairs, P with 1 lone pair.
Parent Tip: Review the logic above to help your child master the concept of covalent compound worksheets.
