Wilhelm Rontgen 1895 German Scientist Playing with a Crookes tube Sitting in a dark lab, tube covered with black paper, held up a book to the tube . . . Image of key appeared on paper painted with Barium across the room The key had been a bookmark Wilhelm Rontgen

Rontgen’s Lab Rontgen thought he was hallucinating Told no one Shut himself in the dark lab for seven weeks Held up a metal plug and saw … his BONES

“Black Magic” Took a picture of wife’s hand (afraid, she never went back to the lab) Showed that these images were real Rontgen began to document and rationalize his work w/ physics knowledge of the time

The Nobel Prize in Physics 1901 Wilhelm Conrad Röntgen Namesake Element: Rontegenium Atomic # 111 Atomic Weight 272 Discovered in 1994, Germany Highly Radioactive, but this element does not emit x-rays

FUSION AND FISSION

First, a little bit about energy

Forms of Energy Heat Chemical Electromagnetic Nuclear Mechanical The five main forms of energy are: Heat Chemical Electromagnetic Nuclear Mechanical

Heat Energy The internal motion of the atoms is called heat energy, because moving particles produce heat. Heat energy can be produced by friction. Heat energy causes changes in temperature and phase of any form of matter.

Chemical Energy Making and Breaking bonds Chemical Energy is required to bond atoms together. And when bonds are broken, energy is released.

Chemical Energy Fuel and food are forms of stored chemical energy.

Electromagnetic Energy Power lines carry electromagnetic energy into your home in the form of electricity.

Electromagnetic Energy Light is a form of electromagnetic energy. Each color of light (Roy G Bv) represents a different amount of electromagnetic energy. Electromagnetic Energy is also carried by X-rays, radio waves, and laser light.

Mechanical Kinetic /Potential

Nuclear Energy The nucleus of an atom is the source of nuclear energy. Energy holding nucleus together

Nuclear Energy Nuclear Energy is the most concentrated form of energy! 2 major reactions :Fission & Fusion

Result: gain or loss of energy Fusion Nuclear fusion is the process by which multiple nuclei join together to form a heavier nucleus. The fusion of two nuclei lighter than iron or nickel generally releases energy. The fusion of nuclei heavier than them absorbs energy. Result: gain or loss of energy

Nuclear Fusion

Nuclear Fusion Example The sun’s energy is produced from a nuclear fusion reaction in which hydrogen nuclei fuse to form helium nuclei.

NUCLEAR FISSION Fission may be defined as the process of splitting an atomic nucleus into fission fragments The fission fragments are generally in the form of smaller atomic nuclei and neutrons Large amounts of energy are produced by the fission process

More about fission Fissile nuclei are generally heavy atoms with large numbers of nucleons The nuclei of such heavy atoms are struck by neutrons initiating the fission process Fission occurs due to electrostatic repulsion created by large numbers of protons within the nuclei of heavy atoms

Nuclear Fission Neutron induced in U235

Neutrons may: Creates two smaller nuclides and free neutrons 1 - Cause another fission by colliding with a U235 nucleus 2 - Be absorbed in other material 3 - Lost in the system If sufficient neutrons are present, we may achieve a chain reaction Creates two smaller nuclides and free neutrons The free neutrons potentially collide with nearby U235 nuclei May cause the nuclide to split as well Each split (fission) is accompanied by a large quantity of E-N-E-R-G-Y

Fission Example

Where does the energy come from? We often say that matter cannot be created nor destroyed. However . . . Einstein taught us that Energy and matter are different forms of the same thing! E = mc2

Mass Defect The nucleus is composed of protons and neutrons the actual mass is less than the mass of the separate particles. The "missing" mass is in the form of energy holding the nucleus together. 4/26/2017

Uranium-238 238U nucleons The nuclear mass (protons & neutrons) of uranium-238 is 238.0003 amu 238U 92 atomic number (protons) A proton is 1.00728 amu A neutron is 1.00867 amu What mass is expected for the nucleus of 238U? 4/26/2017

Uranium-238 92 protons (92)(1.00728) = 92.6698 146 neutrons (92)(1.00728) = 92.6698 146 neutrons (146)(1.00867) = 147.2658 predicted mass = 239.9356 actual mass = 238.0003 mass defect = 1.9353 amu 4/26/2017

Masses of Atoms The nuclear mass of 238U is 238.0003 Why does the Handbook of Chemistry and Physics list the mass of uranium­238 as 238.0508? (92)(0.0005488) + 238.0003 = 238.0508 4/26/2017

Binding Energy The mass defect indicates the total energy involved in holding the nucleus together. To determine the stability of the nucleus, the binding energy per nuclear particle is a better measure. 4/26/2017

Binding Energy of 238U actual mass 238.0003 predicted mass 239.9356 1.9353 amu DE = Dmc2 = 931.5 MeV/amu What is the binding energy per nucleon of 238U?

Binding Energy of 238U Binding energy per nucleon = (1.9353 amu)(931.5 MeV/amu) 238 nucleons = 7.57 MeV 4/26/2017

Binding Energy The nuclei with the greatest binding energy per nucleon 62Ni The nuclei with the greatest binding energy per nucleon are the most stable. 4/26/2017

E = mc2 Matter can be changed into energy In the equation above: E = energy m = mass c = speed of light Small amount of mass becomes a HUGE amount of energy

Chemical Reactions Nuclear Reactions Involve changes in electrons Acids & Bases, combustion, displacement The same atoms appear on both sides of the reaction. Follows Dalton’s Law of Conservation of Mass Small amount of energy generated Burning fossil fuels Nuclear Reactions Involve changes in the nucleus Nuclear fusion, nuclear fission New atoms appear as products of the reaction. Breaks Dalton’s Law of Conservation of Mass Large amount of energy generated 1 million times more than chemical reactions Nuclear fusion on the sun Nuclear fission for reactors

Decay vs. Nuclear Reactions Alpha, beta, and gamma decay occur as ONE atom tries to increase it’s stability by getting rid of a few neutrons, or protons & neutrons. The product is an alpha, beta, or gamma particle and ONE new atom. There is only ONE thing on the left hand side. Nuclear reactions involve more than just getting rid of a few protons or neutrons. The new atoms produced are VERY different elements than the reactant. Nuclear reactions must be started, so there are 2 things on the left hand side. Nuclear fission: makes 2 or more much smaller atoms Nuclear fusion: makes 1 much larger atom

What are the differences between the 2 above nuclear equations?? Nuclear Fission Alpha Decay What are the differences between the 2 above nuclear equations??

Review Mass and Energy are two forms of the same thing; neither can be created nor destroyed but mass can be converted into energy (E = mc2) Fission is a nuclear reaction in which a heavy atomic nucleus is split into lighter atomic nuclei Fusion is a nuclear reaction in which 2 light atomic nuclei are combined into a single, heavier atomic nucleus

Quiz Which nuclear process produces large amounts of energy? A. Fission B. Fusion C. Both fission & fusion D. Neither fission nor fusion

Quiz Fission is the process that _________ atomic nuclei. A. Combines B. Burns up C. Stores D. Splits

Quiz Mass may be converted into energy. A. True B. False

Quiz The fission process requires heavy atomic nuclei. A. True B. False

Quiz Name a nuclear reaction that occurs within the sun:

Bonus Explain this equation: E = mc2