*Radiation-energy travelling through space
*Sunshine is one of the most familiar forms of radiation.
*Ultraviolet- short wavelength
*Stable atom-remains the same
*Unstable atom-changes to be more stable
-have excess energy
*Isotopes-two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei.
*Radioisotopes-radioactive isotopes
*Nucleons-make the nucleus
*Becquerel-one atomic decay per second
*Curie-former unit of radioactivity
*Half-life–time taken for half of the atoms to decay
*Ionizing radiation-produces ions in the materials it strikes
*Several types of ionizing radiation
>>X-rays & Gamma rays-virtually identical
-x-rays are produced artificially
-great penetrating power
-barriers of concrete, lead or water are used for protection from them
>>Alpha particles-two protons & two neurons
-have a positive electrical charge
-have little penetrating power
-they give up their energy over a short distance
-can inflict more severe biological damage
>>Beta particles-smaller than alpha particles
-penetrate 1-2 cm of water
>>Cosmic radiation-more intense at higher altitudes
>>Neutrons-very penetrating
-mostly come from the splitting of atoms inside a nuclear reactor
*Sieverts-absorbed by the body
*Grays- not absorbed by the body
Health risks from ionizing radiation
*Can cause measurable increase in cancer and leukemia
*Can cause genetic mutations
*Can cause sickness and death within weeks of exposure
*Embryos including human fetus are sensitive to radiation damage
*Also used in radiation therapy to kill cancerous cells and can often save lives
*Large doses are used to kill bacteria in food or sterilize bandages and medical equipment
*Background radiation-main source of exposure for most people
Four Ways of protection from radiation
*Limiting time- the dose is reduced and the risk of illness is eliminated by limiting by the exposure time
*Distance- the intensity of radiation decreases with distance from its source
*Shielding- barriers give good protection from penetrating radiation
*Containment- radioactive materials are confined and kept in closed handling facilities
