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

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– # 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

• Fusion– 2 atoms of H combine

to form He– Some mass

converted to energy

• Sunlight