Atomic Structure/ Nuclear Chemistry

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Atomic philosophy that atoms are indivisible and indestructible
John Dalton
Atomic theory
Atomic theory
All elements are composed of tiny indivisible particles called atoms
J.J Thompson
Discovered electron using cathode ray
Robert A Millikan
Discovered electron mass
Electron mass
Eugene Goldstein
Discovered protons
Discovered nucleus by concluding the atom is mostly empty space and that mass + positive charge is concentrated in smaller region
James Chadwick
Discovered neutron
Atoms with different number of neutrons
Non-ionizing nuclear radiation
Longer wavelengths transfers to matter, and vibrates molecules ex microwaves
Shorter wavelengths, carries more energy ex. X-rays
Certain materials emit light when struck with radiant energy and stops when that energy is removed
Discovered X-Rays
Henri Bacquerel
Connected x-Rays and naturally occurring phosphorescence materials
Spontaneous emission of particles and energy from atomic nuclei
Pierre and Marie Curie
Uranium core contains polonium radium uranium (pitchblend)
Penetrating rays and particles emitted by radioactive source
Nuclear radiation begins with unstable isotopes called this
Nuclear radiation is not affected by
Temperature change
Presence of catalyst
Nuclear reactions do not:
Conserve mass (small amount is converted to energy during decay)
Nuclear force
Attractive forces that are between all nuclear particles that are close together (protons neutrons)
Conversion of an atom of one element to the atom of another element, can occur from bombardment of particles to nucleus
Which elements are radioactive?
Elements with atomic number greater than 83
Transuranium elements
Elements above 92 atomic number that none occur in nature
Band of stability
Region where stable nuclei don’t decay or change with time
What determines rate of decay?
Ratio of protons to neutrons
Half life
Time required for one half of the nuclei in a radioisotope sample to decay to products
Nuclei of certain isotopes bombarded with neutrons splitting nucleus into smaller fragments
Nuclei combine to produce nucleus of greater mass, creates more energy than fission
Chain reaction
Produces neutrons that react with more fissionable atoms , must be controlled
Neutron moderation
Slows down neutrons by capturing them for reactor fuel
Categories: Nuclear Chemistry