01Drawing them
Count total valence electrons, connect atoms with single bonds (least electronegative in the center, never H), complete octets on outer atoms, then put leftovers on the center. Use multiple bonds if the center lacks an octet.
Exceptions: B often has 6; elements in period 3+ can exceed 8 (SF₆).
02Notebook box
Total e⁻ = Σ valence (+ charge for anions, − for cations).
Worked example: CO₂ has 16 e⁻ → O=C=O with two lone pairs on each O.