Nuclear Reactions

Notes: You need to write down everything in red for your notes If it is not in red, it is interesting to know, but not required Take notes in CORNELL style – Remember to write the questions and summary - BY THE WAY, THAT IS YOUR HOMEWORK - 5 questions and a 3 sentence summary

Uses For Nuclear Reactions Nuclear weapons

Uses For Nuclear Reactions Nuclear Weapons Power Plants Radiation therapy for cancer patients Radioactive dating using carbon 14 Used to find how old archeological artifacts are Medical tests PET scans

Types of Radiation - Review Alpha decay Strong ionization – grabs electrons Stopped by a piece of paper Beta decay Can penetrate 1 cm into skin Gamma decay High energy – like X-rays Most penetrating – Can go through most materials easily Most damaging radiation

Nuclear Reactions Two types of Nuclear Reactions Fission – splitting atoms apart Atomic bomb Power plants Fusion – fusing atoms together The sun Hydrogen bomb

Nuclear Fission 1. Neutron hits a uranium or plutonium atom 2. The nucleus splits into 2 smaller atoms + free neutrons 3. Each split releases energy in the form of gamma radiation 4. The free neutrons fly away to hit another atom – causing a CHAIN REACTION

Nuclear Fission – Chain Reaction Want to see a chain reaction? Critical mass – The amount of material needed for a chain reaction to happen

Nuclear Fusion Deuterium ( 2 1 H) is combined with Tritium ( 3 1 H) to make Helium Atoms must be smashed together with extreme force to stick together Only happens at millions of degrees – As hot as the Sun There is no nuclear waste in a fusion reaction

Why are nuclear reactions such a big deal? The Answer: E = mc 2 (energy = mass x speed of light squared) This famous equation was discovered by Albert Einstein. Are you ready to know what Einstein knew?

E = mc 2 Energy = mass times the speed of light squared Einstein discovered that mass and energy are related by this equation Only nuclear fission or fusion release close to this much energy So….for 1 gram (speed of light is 299,792,458 m/s) Energy =.001kg x (2.99 x 10 8 m/s) 2 = 89,000,000,000,000 Joules

Benefits of Nuclear Reactions Efficient Energy Source – A lot of energy for a little fuel Fossil fuels are being used up Burning fuel is causing environmental pollution Medical uses for radiation Treating cancer Imaging

Dangers of Nuclear Reactions Nuclear Meltdown Chernobyl (1986) – world’s worst nuclear accident Located in Ukraine – former Soviet Union 31 people killed Surrounding area contaminated for next 50 years

Dangers of Nuclear Reactions Effects of Radiation on Humans Radiation Sickness Cell damage Mutations Increased Risk of Cancer REMEMBER: You are exposed to radiation every day! Your cells will heal themselves from small amounts of radiation.

Dangers of Nuclear Reactions: Effects of Radiation Hand of Scientist at Los Alamos – 9 days after exposure

Public Service Message from Ms. Kuhl. If you don’t want to get mutated…eat your fruits and vegetables Eating fruits and vegetables seems to protect you from cell damage Hiroshima and Nagasaki survivors who ate vegetables had less chance of getting cancer even after being exposed to large amounts of radiation French fries don’t count

Dangers of Nuclear Reactions Environmental Risk Nuclear waste created by nuclear fission is still radioactive Dispose by burying underground Can remain radioactive for hundreds of years Soil and Water contamination Affects plants and animals Food and water become unsafe

The Future? Nuclear power Some countries generate 50% of their power using nuclear fission Does not cause air pollution – global warming The dream of fusion Uses simple materials – Uses water! No nuclear waste But you need millions of degrees to do it Some scientists thought they had discovered cold fusion They were wrong 