1913

Radioactive displacement law

• When a radioactive isotope spontaneously transmutes
• then it may emit a helium nucleus
• or an electron and an electron antineutrino.
• Ernest Rutherford called the first type “alpha decay”;
• and the second type “beta decay.”
• Now we call the second type “beta minus decay.”
• The Fajans and Soddy radioactive displacement law
• tells you what element or isotope the decay results in.
• Alpha decay creates an element
• with two fewer protons and two fewer neutrons.
• Beta decay creates an isotope
• with one additional proton and one fewer neutron.

Other forms of decay

• Other forms of radioactive decay.
• “Beta positive decay” when the isotope
• emits a positron and an electron neutrino.
• This is also called “positron emission.”
• Irène and Frédéric Joliot-Curie induced it
• and called it “artificial radioactivity.”
• “Electron capture” when the nucleus
• captures an electron
• and emits a neutrino.
• “Proton emission” when the nucleus
• emits a proton.
• “Neutron emission” when the nucleus
• emits a neutron.

Transmutation

• Alchemists failed to transmute
• base elements to gold,
• leading many to think
• it was impossible.
• Beyond their means
• and beyond their knowledge
• but not beyond the possible
• since it had happened in the stars.