Ch12
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Transcript of Ch12
The Nucleus of the Atom
Chapter 12
Great Idea:Nuclear energy depends on the conversion of
mass into energy
Chapter Outline
• Empty Space, Explosive Energy• The Organization of the Nucleus• Radioactivity• Energy from the Nucleus
Empty Space, Explosive Energy
Empty Space, Explosive Energy
• Relation of atom to nucleus– What goes on in the nucleus has almost
nothing to do with the atom’s chemistry, and vice versa
– The energies available in the nucleus are much greater than those available among electrons
• E = mc2
Mass Change When a Bow is Drawn
The Organization of the Nucleus
The Organization of the Nucleus
• Rutherford• Nucleus
– Proton– Neutron
• Nucleus gives atom its mass
Atomic Numbers, Isotopes,and the Mass Number
• Atomic number– Number of protons in nucleus
• Dictates the arrangement of electrons• Defines chemical behavior
• Isotopes– Elements with different numbers of
neutrons• Mass number
– Total protons and neutrons
Isotopes
The Strong Force
• Strong force– Holds nucleus together– Operates over short distances– Binding energy
Radioactivity
What’s Radioactive?
• Radioactivity or radioactive decay• Radiation
Using a Geiger Counter to Detect Radioactivity
Science in the Making
• Antoine Henri Becquerel• The Curie family
The Curie Family
The Science of Life
• The CAT Scan
The Kinds of Radioactive Decay
• Alpha decay– Release of particle; composed of 2
protons and 2 neutrons
• Beta decay– Emission of electron– Neutrino– Effect; weak force
• Gamma Radiation– Electromagnetic radiation
Identification of the Alpha Particle
Three Common Types of Radioactive Decay
Radiation and Health
• Ionization– Stripping electron(s)
• Long-term effects– Cancer– Birth defects
Damaging Effects of Radiation
Moving Down the Chart of the Isotopes
The Science of Life
• Radioactive tracers
Half-Life
• Half-life– Average time for decay of ½ batch of
radioactive isotopes
• Wide range of half-lives• Cannot predict half-life
Half-Lives
Radiometric Dating
• Radiometric dating– Measurement of half-life
• Carbon-14– Half-life = 5700 years
• Geology– Need longer half-lives
The Shroud of Turin
Use of Potassium-Argon Dating
Science by the Numbers
• Dating a frozen mammoth– Predictable decay of carbon-14
Decay Chains
• Decay chains– Series of decays– Continues until stable isotope appears
Uranium-238 Decay Chain
Indoor Radon
• Decay of uranium-238• Radon-222
– Undergoes alpha decay– Can build up– Increase ventilation
Energy from the Nucleus
Nuclear Fission
• Fission– Splitting of nucleus
• Nuclear Reactor– Extracts energy
• Meltdown
Nuclear Reactor
Three Mile Island –Partial Meltdown
Fusion
• Fusion– 2 atoms of H combine to form He– Some mass converted to energy
• Sunlight
Fusion Reaction
Technology
• ITER: the future of fusion
Science in the Making
• Superheavy elements
Thinking More about the Nucleus
• Nuclear waste– Management– Yucca Mountain project
• Controversial