Skin Care Flashcards
Ultraviolet light is a form of high energy radiation which makes up part of sunlight and can
Damage our skin
This is because the energy from UV light is so sufficient to break the chemical bonds and the
Skin molecules, which inturn will destroy skin tissue
Excessive exposure to the sun can lead to sunburn and over a longer period of time skin
Skin cancer and ageing of the skin will develop
Products containing what are affective for blocking sun
Zinc oxide
Titanium dioixide
Both of these reflect uv radiation
Tye most effective way to protect the skin is to use?
Sun-block products
Sun screen product that can be used too
But are less affective. They contain chemicals such as p-aminobenzoic acid which absorb UV radiation so less reaches skin
Absorbing small amounts of radiation is
Beneficial, due as it encourages vitamin D growth
Vitamin D is what
Essential for healthy development aide the reversing of dry skin
What is a free radical
A free radical is an atom or group of atoms with an unpaired electron and is highly reactive
Free radical reactions take place in 3 stages
•initiation
•propagation
•termination
Initiation
The formation of a free radical when a molecule absorbs radiation
Propagation
Free radical reacts to form more free radicals
Termination
Free radical combine to slow and eventually stop the reaction
The initiation step
Molecules are split in to chlorine atoms usually using UV light. This is where the chlorine free radicals are formed
The chlorine atoms now have unpaired electron which makes them unstable and reactive
The bond that initially breaks to form free radicals is usually the
Bond that requires least energy to break
Each of the chlorine free radicals produce in the previous step attacks
A methane molecules which removes a hydrogen atom to form hydrogen chloride and a methyl free radical
The methyl free radical then attacks a
Chlorine molecule to form chloromethane and another chlorine free radical
In each of these steps one free radical is generated in order to
Sustain the reaction
Termination step
As the reaction proceeds the number of free radicals steadily
Increases which increases the number of collisions between them forming stable molecules
The chain ends when two free radicals react with each other and form
2 stable molecules
Multiple products are made
Free radical scavenger are molecules that react with
Free radicals to form stable molecules and prevent chain reactions from occurring
Many products like cosmetics, food products and plastics
Contain free radical scavengers
Antioxidants are excellent free radical scavengers as they give
Away electrons while they are being oxidised
