Nuclear Radiation

Radioactivity The process by which an unstable nucleus emits one or more particles of energy in the form of electromagnetic radiation

After the changes in the nucleus, the element can transform into a different isotope of the same element or change into an entirely different element This is known as nuclear decay

There are 3 major forms of emitted radiation

Alpha Particle A positively charged particle, emitted by some radioactive nuclei, that consists of 2 protons and 2 neutrons

Beta Particle An electron emitted during the radioactive decay of a neutron in an unstable nucleus

Alpha vs. Beta

Gamma Ray High-energy electromagnetic radiation emitted by a nucleus during radioactive decay They are high energy electromagnetic waves that can penetrate into the deepest parts of our bodies

3 major forms of emitted radiation

Nuclear Decay When an unstable nucleus emits alpha or beta particles, the number of protons or neutrons changes Ex: Radium-226 (an isotope of Radium with the mass number 226) changes to Radon-222 by emitting an alpha particle

Nuclear Decay Nuclear decay processes can be written as equations similar to chemical reactions The nucleus before decay is like a reactant and is placed on the left side of the equation The products are placed on the right side

Alpha Decay Alpha Particle is the following… or

Beta Decay Beta particle is the following…

Beta Decay Since an electron has a single negative charge, an electron is given an atomic number of -1 when you write a nuclear decay equation The beta particle’s mass is so much less than that of a proton or neutron that it is given a mass number of 0 The mass number before and after the decay does not change The atomic number of the product nucleus increases by 1 because a neutron decays into a proton

Radioactive Decay Rates Half-life – the time required for half of the sample of radioactive nuclei to decay 1st half-life  ½ sample remains 2nd half-life  ¼ sample remains 3rd half-life  1/8 sample remains 4th half life  1/16 sample remains

Radioactive Decay Rates Half-life – the time required for half of the sample of radioactive nuclei to decay 1st half-life  ½ sample remains 2nd half-life  ¼ sample remains 3rd half-life  1/8 sample remains 4th half life  1/16 sample remains

1. Eventually the entire sample will decay 2. With each successive half life, half of the remaining sample decays to form another element

Questions 1. What is strontium’s half life? 2. How much strontium do you have to begin with? 3. After the first half-life, how much is left? 4. After how many half-lifes will there be only 125 grams?

Calculations with Half-Life Starting amount   End amount Start Time (0) End Time What is the half life of a 88.0 gram sample of Carbon that decays to 22.0 grams in 11,400 years? 88.0 g   22.0 g 0 years ? 11,400 years

More Calculations Thallium-208 has a half-life of 3.053 minutes. How long will it take for 100 grams to decay to 25 grams? The half-life of hafnium-156 is .025 seconds. How long will it take a 440g sample to decay to 1/8 of its original mass?

Nuclear Fission Fission – the process by which a nucleus splits into 2 or more smaller fragments, releasing neutrons and energy (The production of lighter nuclei from heavy nuclei)

Nuclear Fission Some of the mass of the particles before the fission reaction is turned into energy after the reaction Matter  energy Neutrons released by fission can start a chain reaction When we control the reaction, we can safely use the energy produced to generate electricity in nuclear power plants

Nuclear Fission

Nuclear Fusion Fusion – the process in which light nuclei combine at extremely high temperatures, forming heavier nuclei and releasing energy Energy is also obtained during the fusion process Stars and sun: energy is produced when H nuclei combine This energy is provided by the high temperature