Section I Flashcards
What causes sun burn?
Ultraviolet light
What is ultraviolet light?
A high energy from of light
How is sun burn caused?
Uv light has sufficient energy for the bonds in the molecules in skin to break
What is another effect of UV light?
Is causes the skin to age
How does sun block prevent sun burn?
It contains chemicals that absorb UV radiation
What happens to electrons when IV light breaks a bond?
One electron goes to each atom at the end of the bond and two free radicals are produced
What is a free radical?
An atom or molecule with an unpaired electron
Are free radicals stable or unstable?
Unstable and very reactive
What is stage one in a chain reaction?
Initiation
Where free radicals are generated
What is stage two in a chain reaction?
Propagation
One free radical reacts and another free radical is produced
What is stage three of a chain reaction?
Termination
Two free radicals react and there are no free radicals in the products
What are two ways to prevent a chain reaction?
Prevent initiation
Force termination
What is a free radical scavenger?
Molecules what react with free radicals to form stable molecules
Give two examples of free radical scavengers
Vitamin C and E
What type of molecule is alwaysa free radical scavenger?
Antioxidants
Give three things free radical scavengers are added to to prevent further reaction?
Cosmetics- reduce damaging effects of exposure to UV radiation
Food- ‘mop up’ free radicals to stop oxidation reactions causing food to go off
Plastics- stop them disintegrating due to UV exposure
