Skincare

Question 1

What does the body produce as a defence to UV light?

Answer 1

Melanin

Question 2

What molecules can UV radiation cause to breakdown?

Answer 2

Collagen

Question 3

How do sun creams protect you from UV radiation?

Answer 3

Nanoparticles of metals - such as titiuamoxide & zincoxide - which reflect UV light/radiation away from the skin

Organic chemicals - such as Vitamin C, betacartin & melanin - that can absorb UV radiation and change it into heat

Question 4

How does UV radiation damage the body?

Answer 4

Breaks the bonds in molecules

Question 5

What is a free radicals

Answer 5

A free radical is an atom or group of atoms with an unpaired electron and is highly reactive.

e.g singular Fluorine & Chlorine atoms

Question 6

How do you make a free radical

Answer 6

UV light can break the bonds in molecules such as Br_2, leading to two Br atoms with unpaired electrons.

Question 7

What are the steps of a free radical chain reaction?

Answer 7

Initiation -
Propagation -
Termination - when a free radical cholidies with a free radical

Question 8

What happens in the initiation stage of a free radical reaction?

Answer 8

Free radicals are generated

Question 9

What happens in the propagation stage of free radical reactions?

Answer 9

In each of the propagation steps, one free radical enters the reaction and another free radical is generated. These steps ‘propagate’ or sustain the chain reaction.

Question 10

What happens in the termination stage of a free radical reaction?

Answer 10

Termination steps are reactions in which free radicals are used up and not regenerated. Such reactions bring the chain reaction to an end.

Question 11

What is the symbol for a free radical?

Answer 11

•

e.g OH• & Cl•