Structure and Properties of Organic Molecules: Hybridization, Bonding, and Molecular Properties

Structure and Properties of Organic Molecules

Multiple Bonds

Organic molecules often contain multiple bonds, which significantly influence their structure and reactivity. Multiple bonds include double and triple bonds, each with distinct bonding characteristics.

• Double bond: Consists of two pairs of shared electrons between atoms, forming one sigma (σ) bond and one pi (π) bond.

• Triple bond: Consists of three pairs of shared electrons, forming one sigma (σ) bond and two pi (π) bonds.

• Example: In ethylene (C2H4), the carbon-carbon double bond contains one σ and one π bond.

Additional info: Sigma bonds result from head-on orbital overlap, while pi bonds result from side-to-side overlap of p orbitals.

Hybrid Orbitals

Hybridization is the process by which atomic orbitals mix to form new, equivalent hybrid orbitals, which determine molecular geometry and bonding properties.

sp Hybrid Orbitals

• Formation: One s and one p orbital combine to form two sp hybrid orbitals.

• Geometry: Linear electron pair geometry.

• Bond Angle: $180^{\circ}$

• Example: Acetylene (C2H2) has sp-hybridized carbons.

sp2 Hybrid Orbitals

• Formation: One s and two p orbitals combine to form three sp2 hybrid orbitals.

• Geometry: Trigonal planar electron pair geometry.

• Bond Angle: $120^{\circ}$

• Example: Ethylene (C2H4) has sp2-hybridized carbons.

sp3 Hybrid Orbitals

• Formation: One s and three p orbitals combine to form four sp3 hybrid orbitals.

• Geometry: Tetrahedral electron pair geometry.

• Bond Angle: $109.5^{\circ}$

• Example: Methane (CH4) has sp3-hybridized carbon.

Summary Table: Hybridization and Geometry

Hybridization	Orbitals Combined	Geometry	Bond Angle
sp	1 s + 1 p	Linear	180°
sp2	1 s + 2 p	Trigonal planar	120°
sp3	1 s + 3 p	Tetrahedral	109.5°

Additional info: Hybridization explains molecular shapes predicted by VSEPR theory and observed experimentally.