Warm-up Sodium-24 beta decays. What new isotope is formed when it decays? How much new isotope is formed after 45 hours of a decaying Na-24? How much old isotope is left after 45 hours? How much C-14 is left after 11,400 years? How much old isotope is left after 5 half lives?

Warm-up Write alpha, beta and electron capture decay Rx for Na-24 Draw the shift in #p+ and #no into the graph below using arrows marked with the decay symbol #no --- X Na-24 #p+

25.2 Radiation in your life

Nuclear Fission Fission = splitting (of a nucleus) creates a chain reaction of high speed neutrons that split more nuclei generates enormous amounts of energy

2 Types of Fission uncontrolled nuclear reaction – A Bomb controlled nuclear reaction – nuclear power plant

Controlled Nuclear Fission Speed of the neutrons is lowered by graphite rods The coolant is heated that power steam turbines to generate electricity

Nuclear Reactor

How does a Nuclear PP works NPP san onofre

Below are arguments pro/against Nuclear Energy Forever storage of nuclear waste no pollution, greenhouse gas emission (CO2) Accidents that can lead to widespread contaminations (Three Mile Island, Chernobyl, Fukoshima) independence from oil (political costs…) long term, large scale, reliable energy production

Nuclear Fusion Fusion: combining (two small nuclei) more energy than nuclear fission Also creates a chain reaction Sun does nuclear fusion

Nuclear Fusion life nf

Forces Within the Nucleus Electromagnetic repulsion: Protons repelling each other Nuclear forces: neutrons and nuclear binding energy glue protons together “cosmic glue” Nuclear forces > electromagnetic repulsion, element is stable Nuclear forces < electromagnetic repulsion, radioisotope

Ionizing Radiation Radiation with enough energy to knock electrons of the exposed elements and change them Formation of ions – charged atoms (#p+ and e- is not equal!!!) Particle radiation: alpha and beta particles Electromagnetic waves: UV, X-rays, gamma rays

Electromagnetic Spectrum

DNA Damage from Radiation

Dose vs Damage -radiation doses are measured in Sieverts

radiation cellphones and tumors

Nuclear Medicine Radiation treatment of cancer. Radiation affects quickly dividing cells more than non-dividing cells (normal) Injection of Iodine-131 for the detection of thyroid function:

Research Radiolabeling of molecules, cell parts with radioisotopes H-3, S-35…

Fossil dating When the animal is alive it incorporates radioactive trace elements from environment Example: C-14 alongside C-13, C-12 T1/2 = 5700 years When animal dies/fossilizes C-14 is not replaced but undergoes transmutation to N-14. What type of transmutation turns C-14 into N-14? The older the fossil the more C-14 is gone

Half-life of selected isotopes Bismuth-212 60.5 sec Sodium-24 15 hours Iodine-131 8.07 days Hydrogen-3 12.3 years Cobalt-40 605.26 years Carbon-14 5700 years Uranium-238 4.5 billion years

Half-life curve

Warm-up Sketch the reactor of a nuclear power plant, label the parts and explain their function