Ionisation

How some EM Radiation causes Ionisation

• All substances are made of atoms and molecules
• All atoms have electrons orbiting them
• When a photon hits an atom or molecule, if it has enough energy, it can remove an electron
• This changes the atom or molecule
• This process is called Ionisation...
• The changed atoms or molecules go on to initiate other chemical reactions
• It takes a lot of energy to remove an electron
• So only the EM Radiations that at have high enough photon energy can cause ionisation.
• These are ultraviolet, X-rays and gamma rays
• These types of electromagnetic radiation are called ionising radiation
• Some substance (radioactive materials) emit ionising gamma radiation all the time
• Hence why radioactive materials are so dangerous!!
• 
• Bildunterschrift: Ionisation: the energy source (photons) hit into the orbiting shells where the electrons are and knock one off

Ionisation is dangerous!

• If it happens in your cells, it is very dangerous
• The cells contain very important molecules, such as DNA molecules
• DNA contain the instructions for the cell and are important in cell division - when new cells are made
• If your cells are exposed to ionising radiation, DNA molecules can become damaged. This can cause mutations.
• So, the cells may start to divide over and over again, without stopping....this is CANCER.
• Very high doses of radiation can kill your cells....this is radiation sickness
• We're all exposed to ultraviolet light from the sun. UV radiation is ionising so if you stay in it long enough, it can damage living cells in the skin.
• This can lead to sunburn or even skin cancer.
• Increased exposure means more damage.
• So, the longer you're exposed the more damage it will cause.
• 
• Bildunterschrift: The damaged cell has had its DNA damage too, and it is now a mutated cell. It then divides and makes more mutated cells, causing a larger amount of mutated cells, which is basically cancer.

Protection against dangerous radiation...

• UV Radiation
• Easily protect
• Using physical barriers - such as clothes or sunscreen or sunblock
• X-Rays
• When having an X-ray, the radiographer puts lead shields over parts of the body that aren't being investigated
• Lead absorbs the X-ray, protecting you from any unnecessary exposure
• Radiographers also where lead aprons or stand behind concrete to protect themselves
• X-Rays - what do they do?
• Radiographers take X-ray pictures to see if you have broken bones
• X-rays pass easily through flesh
• BUT are absorbed by denser materials like bone and metal
• So it's the varying amount of radiation absorbed that makes an X-ray image.
• X-ray imaging also used in airports
• Checks the contents of passengers bags