Unit 2: Chapter 10 - Skin Care Flashcards
What is UV radiation?
Ultraviolet (UV) radiation is a high-energy form of light, present in sunlight.
What can UV light provide for a molecule?
UV light can provide sufficient energy to break certain covalent bonds within molecules.
What does the fact that the UV light can break bonds within molecules mean for us?
The UV light can cause sunburn and accelerates ageing of the skin.
How can we protect ourselves for the harmful effects of UV light?
We can use sunblock/sun cream products which prevent the UV light reaching the skin.
Can UV light exposure to the skin be good for us?
Yes as it produces vitamin D however most of the effects of UV light are harmful and dangerous.
What forms when UV light breaks bonds?
Free radicals.
What are free radicals?
Free radicals are atoms or molecules that are highly reactive due to the presence of unpaired electrons from the breaking of the bond and although highly reactive they are electrically neutral.
Why are free radicals so reactive?
They want to form a stable octet and start chain reactions.
What are the 3 steps in a free radical chain reaction?
Initiation, propagation and termination.
What happens in initiation?
In initiation the free radical is formed when the bond with the lowest bond enthalpy (where the covalent bond is easier to break) is broken.
What happens in propagation?
The free radical formed in initiation will react with the other bond which had the higher bond enthalpy (the bond that was harder to break down) is broken which produces more and different free radicals. The two or more free radicals can then form a more stable molecule like when H and Cl free radicals bond to from HCl. This can then release more free radicals which starts a chain reaction.
What happens in termination?
In termination all of the free radicals will combine to produce stable molecules.
What can be used that prevent sunburn and ageing on the skin?
Free radical scavengers.
What do free radical scavengers do to prevent sun burn?
Free radical scavengers combine with the free radicals on the skin to form stable compounds and stop the reactions that cause the skin to age.
What are the most common free radical scavengers found in skin cream called And how do they work?
Ester of vitamin C and E. When applied both hydrolyse to form vitamin C and E which then combine with the free radicals on the skin to form stable molecules.
