2.  Radioactivity (Radiation) is the release of high-energy particles and rays of energy from a substance as a resultof changes in the nuclei of its atoms. › When atoms radiate, another element can be formed. › We call it radiation only when the energy comes from the nucleus of the atom

3.  Natural radiation exists all around us, from: radioactive substances in the Earth´s crust to cosmiv rays from outer space that bombard Earth. Trace amounts from these sources can be found in our food and water.

4.  Being exposed to radioactive materials can be beneficial or harmful. Beneficial (GOOD) Radiation Exposure Harmful Radiation Exposure -Medical imaging (iron-59) -Cancer treatment: radiation therapy -X-rays -Electricity generation -Beta and Gamma radiatio can penetrate your skin and damage your cells. -High-energy particles and waves damage DNA in our cells.

5. Increasing Frequency Decreasing Wavelength The the higher the frequencyof the radiation (i.e.the shorter the wavelength)= the more harmful the radiation is for you!

6. How Radiation Happens: 1. An atom has an unstable nucleus 2. The unstable nucleus splits apart 3. Energy is released (we say ¨a nucleur reaction¨occurs) 4. The atom will contunue to radiate until it becomes stable (often ending up as different atoms)

7. An element may only have certain isotopes that are radioactive. These are called radioisotopes.

8.  Isotopes are different types if the same element, that have a different number of neutrons in the nucleus.  Isotopes have the same number of protons and electrons-so, they have the same atomic number and symbol BUT…  Different number of neutrons and therefore different mass number  Mass number refers to the #protons (atomic number) + #neutrons in an isotope

9.  Isotopes are written by: 1. Putting the mass number at the top left. 2. Putting the atomic numberat the bottom left. Potassium has three isotopes:

11. When atoms are unstable, they break apart to become new, more stable atoms, and release radiation. There are three types that can be released: 1.Alpha 2.Beta 3.Gamma

12.  Alpha radiation is a tream of alpha (helium) particles › Charge: +2 (2 protons) › Alpha particles are the same as a helium atom. So we represent radiation:

13.  The release of alpha particles is called alpha radiation.  Alpha particles are slow and not very harmful. A sheet of paper will stop an alpha particle.

15.  Beta radiation is a stream of beta (electron) particles,. › Charge: -1 (1 electron) › We represent radiation as: › Beta particles are faster and more harmful than alpha. A sheet of metal foil (aluminum foil) will stop a beta particle.

17.  Gamma radiation is a ray of high energy. › No charge 0) and no mass (almost no mass). › Gamma radiation is the highest energy form of the electormagnetic radiation (most dangerous)

18.  Gamma decay results from energy being released from a high-energy nucleus. It is shown by:  It takes thick blocks of lead or concrete to stop gamma rays.

19.  Gamma rays accompany the alpha decay og uranium-238.

23. * Means the nickle nucleus has extra energy!