Functional Group	Structure	Hybridization	Geometry	Polarity	Typical Reactivity
Alkane	C–C, C–H	sp³	Tetrahedral (109.5°)	Nonpolar	Unreactive scaffold
Alkene	C=C	sp²	Trigonal planar (120°)	Weakly polar	Electrophilic addition
Alkyne	C≡C	sp	Linear (180°)	Weakly polar	Addition; acidic terminal C–H
Arene	Delocalized ring	sp²	Planar hexagon	Nonpolar	Electrophilic aromatic substitution
Alkyl halide	C–X	sp³	Tetrahedral	Polar	Substitution, elimination
Alcohol	C–O–H	sp³	Tetrahedral / bent at O	Polar	Weak acid; nucleophile; substrate for substitution/elimination
Phenol	Ar–O–H	sp²	Planar	Polar	More acidic than alcohols; activates ring toward EAS
Ether	C–O–C	sp³	Bent at O	Polar bonds, no H-bond donor	Largely unreactive; common solvent
Aldehyde	R–CHO	sp²	Trigonal planar	Strongly polar	Nucleophilic addition
Ketone	R–CO–R′	sp²	Trigonal planar	Strongly polar	Nucleophilic addition
Carboxylic acid	R–COOH	sp²	Trigonal planar	Highly polar	Acidic; acyl substitution
Acid chloride	R–COCl	sp²	Trigonal planar	Very polar	Most reactive acyl substitution
Anhydride	R–CO–O–CO–R′	sp²	Trigonal planar	Polar	Reactive acyl substitution
Ester	R–CO–O–R′	sp²	Trigonal planar	Polar	Moderate acyl substitution; hydrolysis
Amide	R–CO–NR′₂	sp² (C and N)	Planar	Polar, N lone pair delocalized	Least reactive acyl derivative; very stable
Acetal/Hemiacetal	C(OR)(OR)/C(OH)(OR)	sp³	Tetrahedral	Polar	Reversible, acid-catalyzed; protecting group
Amine	C–NR₂	sp³	Trigonal pyramidal (~107°)	Polar	Basic; strongly nucleophilic
Aromatic heterocycle	Ring with N/O/S	sp²	Planar	Variable	Substitution; heteroatom-directed reactivity

---