KA6- Skin Care Flashcards
Sunlight
Contains ultraviolet light
Ultraviolet light (UV)
A very high energy form of light
Capable of breaking chemical bonds
Has enough energy to break covalent bonds leaving 2 atoms with unpaired electrons known as free radicals
UV exposure
Beneficial because allows us to make vitamin D
Causes skin to age
Too much UV exposure causes sunburn
Sunburn
Linked to skin cancer so chemists have developed product to protect our skin
Sun screens
Contains compounds that filter the UV light so less reaches the skin
Sun block
Contains compounds that reflect the UV so that it does not reach the skin at all
Free radicals
Highly reactive as it has an unpaired reaction
Will react rapidly with any other atom/molecule
Can take part in chemical reactions that involves the steps initiation, propagation, termination
Substitution reactions
When a H atom substituted by Cl
Initiation, propagation, termination
Substitution reaction stage 1
Initiation
UV light provides energy for the homolytic fission of halogen into reactive halogen atoms or free radicals
Substitution reaction stage 2
Propagation
Free radicals collide with other species, free radicals maintained produces hydrogen radical, reaction continues until reactants used up or until free radicals used up by collision with eachother
Substitution reaction stage 3
Termination
Free radicals used up by collision with each other
Free radical scavengers
Compounds that combine with free radicals to form stable molecules
As they form stable molecules, they help to stop the free radical chain reactions that cause the skin to form wrinkles
Added to food and plastics to prevent spoiling or damage by free radicals
Molecules that react with free radicals to prevent chain reactions
Examples- vitamins C and E
