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16.1 Nuclear Weapons
New ideas for today
• Radioactivity
• Carbon dating
• Fission
• Nuclear weapons
• Nuclear reactors
Radioactivity was first discovered in 1896 by
Henri Becquerel (he left some pitchblende on
an envelope of unexposed film in a drawer.)
He won a Nobel Prize
in 1903 for his
discovery.
Discovery of Radioactivity
Marie Curie, the first person to win two Nobel Prizes and the only person
to win one in physics and chemistry, discovered the radioactive elements
radium and polonium. Element number 96, Curium, was named after her.
Atomic Nucleus
• Atoms are usually electrically
neutral
• At the center of an atom is its
nucleus
– Extremely small
1/100,000th of the atom’s
diameter, measured in 10-15
meters or “femtometers”
– Contains most of the atom’s
mass and most of the atoms
potential energy (E=mc2)
– Contains protons
and neutrons
Structure of Nucleus
• Nucleus contains two kinds of nucleons
– Protons (+) and Neutrons (neutral)
• Two forces are active in a nucleus
– Electrostatic repulsion between protons
– Nuclear force attraction between nucleons
Short distances:
nuclear > electric
Long distances:
electric > nuclear
