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

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=mc 2

The Organization of the Nucleus

Rutherford Nucleus –Proton –neutron Nucleus gives atom its mass

Atomic Numbers, Isotopes, and the Mass Number Atomic number –# of protons in nucleus Defines chemical behavior Isotopes –Elements with different numbers of neutrons Mass number –Total protons and neutrons

The Strong Force Strong force –Holds nucleus together –Operates over short distances –Binding energy

Radioactivity

What’s Radioactive? Radioactivity or radioactive decay Radiation

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

Moving Down the Chart of the Isotopes

Radiation and Health Ionization –Stripping electron(s) Long-term effects –Cancer –Birth defects

Half-Life Half-life –Average time for decay of ½ batch of radioactive isotopes Wide range of half-lives Cannot predict half-life

Radiometric Dating Radiometric dating –Measurement of half- life Carbon-14 –Half-life = 5700 years Geology –Need longer half- lives

Decay Chains Decay chains –Series of decays –Continues until stable isotope appears

Indoor Radon Decay of Uranium-238 Radon-222 –Can build up –Increase ventilation

Energy from the Nucleus

Nuclear Fission Fission –Splitting of nuleus Nuclear Reactor –Extracts energy Meltdown

Fusion –2 atoms of H combine to form He –Some mass converted to energy Sunlight