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Difficulty: HardTetrahedral Carbon, Bonding, and Hybridization

Match each structural feature or carbon center of 2-methylbut-1-en-3-yne (HC≡C−C(CH3)=CH2HC\equiv C-C(CH_3)=CH_2) on the left with its corresponding hybridization state, geometric descriptor, or orbital overlap description on the right.

  • The C2−C3C_2-C_3 single bond connecting the alkyne and alkene carbon centersσ\sigma-bond formed by head-on overlap of an spsp hybrid orbital and an sp2sp^2 hybrid orbital
  • The methyl carbon center (−CH3-CH_3)sp3sp^3 hybridization with tetrahedral geometry and ≈109.5∘\approx 109.5^\circ bond angles
  • The alkene double bond between C3C_3 and C4C_4One σ\sigma-bond (sp2−sp2sp^2-sp^2 overlap) and one π\pi-bond (sideways 2p−2p2p-2p overlap)
  • The terminal acetylenic carbon center (C1C_1)spsp hybridization with linear geometry and 180∘180^\circ bond angle

Answer

The correct pairings are: (1) The C2−C3C_2-C_3 single bond matches with the σ\sigma-bond formed by head-on sp−sp2sp-sp^2 hybrid orbital overlap. (2) The methyl carbon center matches with sp3sp^3 hybridization, tetrahedral geometry, and ≈109.5∘\approx 109.5^\circ bond angles. (3) The alkene double bond matches with one σ\sigma-bond (sp2−sp2sp^2-sp^2) and one π\pi-bond (2p−2p2p-2p). (4) The terminal acetylenic carbon matches with spsp hybridization, linear geometry, and 180∘180^\circ bond angle.
Each carbon atom in 2-methylbut-1-en-3-yne adopts a hybridization state determined by its steric number (number of attached atoms and lone pairs). C1C_1 and C2C_2 are spsp-hybridized (linear, 180∘180^\circ), C3C_3 and C4C_4 are sp2sp^2-hybridized (trigonal planar, 120∘120^\circ), and the methyl group carbon is sp3sp^3-hybridized (tetrahedral, 109.5∘109.5^\circ). Consequently, single bonds between differently hybridized carbons utilize hybrid orbitals corresponding to each carbon (sp−sp2sp-sp^2 for C2−C3C_2-C_3), and double bonds consist of one σ\sigma bond (sp2−sp2sp^2-sp^2) plus one π\pi bond (2p−2p2p-2p).

Step-by-Step Solution

1
Analyze the expanded structural formula of 2-methylbut-1-en-3-yne
H−C(1)≡C(2)−C(3)(CH3)=C(4)H2H-C(1)\equiv C(2)-C(3)(CH_3)=C(4)H_2
Determining the bonding domains around each carbon atom establishes its hybridization state and structural role.
2
Determine hybridization state for each carbon center
C1C_1 (spsp), C2C_2 (spsp), C3C_3 (sp2sp^2), C4C_4 (sp2sp^2), and methyl carbon (sp3sp^3)
Carbons with 2 electron domains are spsp (linear), 3 domains are sp2sp^2 (trigonal planar), and 4 domains are sp3sp^3 (tetrahedral).
3
Map orbital overlap types to specific bonds
C2−C3C_2-C_3 is an sp−sp2sp-sp^2 σ\sigma-bond; double bond C3=C4C_3=C_4 comprises an sp2−sp2sp^2-sp^2 σ\sigma-bond and a 2p−2p2p-2p π\pi-bond.
Single bonds are formed by head-on overlap of hybrid orbitals, while double bonds consist of one coaxial σ\sigma bond and one collateral π\pi bond.
4
Match left items with their corresponding right item descriptions based on hybridization and geometry principles
All 4 items are accurately matched to their structural characteristics.
Ensures complete alignment between structural features and underlying orbital hybridization properties.

Key Concept

Orbital Hybridization and Overlap Types in Hydrocarbon Frameworks
Estimated Time:2m 0s
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Topics

Tetrahedral Carbon, Bonding, and Hybridization

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