1. H₂: Two hydrogen atoms, each with 1 valence electron, share their electrons to form a single covalent bond (H-H). Each H achieves a duet (2 electrons), stable for hydrogen.
2. F₂: Each fluorine atom has 7 valence electrons. They share one pair of electrons, forming a single bond. Each F now has 8 electrons (an octet) — 6 non-bonding and 2 bonding.
3. O₂: Each oxygen atom has 6 valence electrons. They share two pairs of electrons, forming a double bond (O=O). Each O now has 8 electrons — 4 non-bonding and 4 bonding.
4. N₂: Each nitrogen atom has 5 valence electrons. They share three pairs of electrons, forming a triple bond (N≡N). Each N now has 8 electrons — 2 non-bonding and 6 bonding. Yes, this is a triple bond.
5. BF₃: Boron has 3 valence electrons; each fluorine has 7. Boron shares one electron with each of three fluorine atoms, forming three single bonds. Boron ends with 6 electrons (incomplete octet), while each F has 8.
6. NH₃: Nitrogen has 5 valence electrons; each hydrogen has 1. Nitrogen shares one electron with each of three hydrogen atoms, forming three single bonds. Nitrogen retains one lone pair. N has 8 electrons (octet); each H has 2 (duet).
7. CO₂: Carbon has 4 valence electrons; each oxygen has 6. Carbon forms double bonds with both oxygen atoms (O=C=O). Carbon shares 4 electrons (two per bond), achieving an octet. Each oxygen shares 4 electrons and has 4 non-bonding, achieving an octet.
8. CH₄: Carbon has 4 valence electrons; each hydrogen has 1. Carbon shares one electron with each of four hydrogen atoms, forming four single bonds. Carbon achieves an octet; each H achieves a duet.
9. H₂O (Dihydrogen monoxide): Oxygen has 6 valence electrons; each hydrogen has 1. Oxygen shares one electron with each of two hydrogen atoms, forming two single bonds. Oxygen retains two lone pairs. O has 8 electrons (octet); each H has 2 (duet).
10. SO₂: Sulfur has 6 valence electrons; each oxygen has 6. Sulfur forms a double bond with one oxygen and a single bond with the other, using one of its lone pairs to form the second bond (resonance structure). The sulfur atom has an expanded octet (10 electrons) or can be represented with one double bond and one single bond with formal charges. Each oxygen achieves an octet.
Parent Tip: Review the logic above to help your child master the concept of covalent bonding worksheet.
