VSEPR Geometries & Angles: Valence shell electron pair repulsion governs 3D shape. Saturated carbon forms sp³ tetrahedral ($109.5^\circ$), alkene double bonds form sp² trigonal planar ($120^\circ$), and alkyne triple bonds form sp linear ($180^\circ$).
Bond Length Standards: Single $C-C = 1.54\,\text{Å}$, Double $C=C = 1.34\,\text{Å}$, Triple $C\equiv C = 1.20\,\text{Å}$, $C-H = 1.09\,\text{Å}$, $C-O = 1.43\,\text{Å}$, $C=O = 1.22\,\text{Å}$.
CPK Color Standard: C Gray H White O Red N Blue Cl Green Br Rust S Yellow
Measurement Mode: Click any 2 atoms to measure interatomic distance ($\text{Å}$ and $\text{pm}$). Click 3 consecutive atoms to calculate bond angle ($\theta$).