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