2.2.1 Covalent Bond & Lewis Formulas
Electrostatic attraction and the octet rule.
The Covalent Bond
Defintion
The electrostatic attraction between a shared pair of electrons and the positively charged nuclei.
The Octet Rule
Atoms tend to gain, lose, or share electrons until they are surrounded by eight valence electrons (stable noble gas configuration).
Exceptions
- Hydrogen (H): Stable with 2 electrons.
- Beryllium (Be): Stable with 4 electrons (e.g., BeCl₂).
- Boron (B): Stable with 6 electrons (e.g., BF₃).
Drawing Lewis Formulas
- Count Valence e⁻: Sum group numbers. Adjust for ions.
- Skeleton: Connect atoms with single bonds (least electronegative in center).
- Fill Outer: Complete octets for outer atoms (duet for H).
- Check Center: If center lacks octet, share lone pairs to form double/triple bonds.