Radioactivity radiation

Nuclear Reactions Chain reactions: the neutrons emitted during fission hit other atoms causing those nuclei to split also Critical Mass: when each neutron emitted splits another atom

Nuclear Reactions Nuclear reactions: 1938 Otto Hahn and Fritz Strassmann Found that when you hit the nucleus of a large atom the nucleus splits and energy is released nuclear reactions (10 minutes) fission and fusion (11 minutes)

Charge of an Atom The charge of an atom is determined by the number of protons in the atom’s nucleus Negatively charged atoms are attracted to positively charged atoms

The Strong Force The strong force: a short range force that causes protons and neutrons to be attracted to each other 100 times stronger than the electrical force

Radioactivity Stable atoms: when the strong force is able to keep the nucleus together Radioactivity: when the nucleus of an atom becomes unstable and decays giving off matter and energy Example: anything over the atomic number of 83

Radioactivity Unstable and stable nuclei: atoms with an unequal number of neutrons and protons are unstable

Discovery of Radioactivity 1896 Henri Becquerel

Nuclear Decay Nuclear radiation: When an unstable nucleus decays and particles and energy are emitted from it radioactivity

Alpha Particles Alpha particle: a particle made of 2 protons and 2 neutrons Alpha decay: when an alpha particle is emitted from an atom The least penetrating form of nuclear radiation but it can damage human cells Radiation

Beta Particles Beta Particles: decay when an electron is emitted from the atom Beta Decay: one of the neutron decays into a proton so the atom is not the same atom anymore Damage is much more penetrating Can damage human cells

Gamma Rays Gamma rays: electromagnetic waves that have the Highest frequency, highest energy and shortest wavelength Do damage to human cells

Half-life Half-life: the time it takes for the nucleus to decay by half

Radioactive Dating Radioactive dating: uses the half-life of atoms to date rocks and fossils Carbon dating: uses the decay of carbon isotopes to date plant and animal remains Accurate up to 50,000 years radioactive dating

Radioactive dating Uranium Dating: uses the decay of uranium to date rocks and fossils Uranium has a half-life of 700 million years to 4.4 billion years

Detecting Radioactivity Cloud chamber: a chamber filled with water vapor that is used to detect alpha or beta radiation Bubble Chamber: a superheated liquid that will boil in the presence of radiation Electroscope: detects electricity and can be used to detect radiation Geiger Counter: a device that detects radiation by producing an electric current Fukushima

history of radiation Chernobyl Fukushima what could survive an atomic bomb? the Manhattan project