Colour by Design Flashcards Preview

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

Flashcards in Colour by Design Deck (7)
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1
Q

What is a conjugated system

A

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

2
Q

Colourless and coloured objects

A

Colourless objects reflect all visible light and do not absorb any

Coloured objects absorb the wavelength of the colour they appear

3
Q

What are complimentary colours

A

Two colours which combined together produce white light

4
Q

Factors affecting colour

A
  • 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

5
Q

The geometry of benzene

A
  • The benzene ring is a regular, planar hexagon
  • All the bond angles are 120 degrees
  • All the carbon-carbon bonds are the same length
6
Q

Stability of delocalised structures

A

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

7
Q

Benzene reaction with bromine

A

Electrophilic substitution with an iron catalyst to form bromobenzene and HBr