OCR - A-Level - Chemistry - Alkanes and Alkenes (with bonding)

OCR - A-Level - Chemistry - Alkanes and Alkenes (with bonding)

1. S-orbitals have sigma bonds between them

   • In sigma bonds, the overlap region of the electron orbitals lies directly between the two nuclei

2. Alkanes are non-polar (the polarity due to the differing electronegativities of carbon and hydrogen is negligible)

   • This is the case for all alkanes

3. Double bonds are stronger than single bonds, but are not double the strength

4. The intermolecular forces for alkanes are London dispersion forces (temporary dipole)

5. The boiling point of alkanes and alkenes increases as the length of the carbon chain increases.

   • There are more bonds to break, so more energy is required to do so.

6. Branched hydrocarbons have lower boiling points than straight-chain hydrocarbons.

   • There is more contact surface area between molecules, so more van der Waals forces. As a result, more energy is needed to break this.

7. P-orbitals have pi bonds between them

   • In pi bonds, the electron orbital overlap regions lie off to the side of the line connecting two nuclei

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