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OCR A-Level Chemistry Salters B > Colour by Design > Flashcards

Flashcards in Colour by Design Deck (7)
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What is a conjugated system

A conjugated system has alternating single and double bonds, allowing the overlap of p-orbitals


Colourless and coloured objects

Colourless objects reflect all visible light and do not absorb any

Coloured objects absorb the wavelength of the colour they appear


What are complimentary colours

Two colours which combined together produce white light


Factors affecting colour

-The more electrons that are delocalised in the conjugated system, the smaller the energy gap
-Smaller energy gaps result in the absorption of longer wavelengths of light absorbed

It usually takes 5 pi bonds in a conjugated system for the system to start absorbing visible light


The geometry of benzene

-The benzene ring is a regular, planar hexagon
-All the bond angles are 120 degrees
-All the carbon-carbon bonds are the same length


Stability of delocalised structures

The more delocalised a system is, the more stable it is


Benzene reaction with bromine

Electrophilic substitution with an iron catalyst to form bromobenzene and HBr