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Created bylily heavner
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Niels Bohr discovered the electrons' orbits and
that there were more electrons in the outer
orbits than in the inner orbits. He also saw that
radiation was emitted when an electron would
jump from one orbit to another.Ernest Rutherford discovered protons in the
nucleus.Henry Moseley labeled the elements with
atomic numbers based upon the number of
electrons in an atom rather than on their atomic
mass.James Chadwick discovered neutrons and
identified isotopes.J. D. Cockroft and Ernest T. S. Walton worked
together in splitting the atom when working
with lithium which they bombarded with
protons. The lithium nucleus was divided into
two helium nuclei.Ernest O. Lawrence, Milton Stanley Livingston
and Milton White worked on the first cyclotron
at the University of California in Berkeley. A
cyclotron is in the picture below.Glenn Seaborg identified lanthanides and
actinides which are elements with atomic
numbers higher than 92 and are placed in a
separate section on the bottom in today's
Periodic Table.there are 117 different elements.
The most recent elements discovered are
meitnerium, darmstadtium, and ununquadium.Hennig Brand invented the Philosopher's Stone,
turns metals into pure gold
. He also discovered phosphorus.Robert Boyle also discovered phosphorus
without knowing about Hennig Brand's
discovery.47 elements had been discovered and named.
Scientists began to see patterns in their atom
structures.John Newlands organized the 56 then known
elements into eleven separate groups based
upon their atom structure.Dimitri Mendellev used John Newlands'
grouping and organized the elements into what
is now known as the periodic table. He used the
atomic mass as the primary characteristic to
decide where each element belonged in his
table. The elements were arranged in rows and
columns. He even left spaces for elements to be
discovered because of the pattern he saw once
he started organizing those elements known at
that that time.Antoine Becquerel discovered radioactivity.Ernest Rutherford named three types of
radiation: alpha and beta and gamma rays.Pierre and Marie Curie began their work and
discovered radium and polonium. They also
discovered that beta particles were negatively
charged.Sir William Ramsay and Lord Rayleigh
discovered the noble gases and they were
added to the periodic table as group O.J. J. Thomson discovered electrons which were
small negatively charged particles.John Sealy Townsend and Robert A. Millikan
further investigated electrons and were able to
determine their exact charge and mass.Antoine Becquerel discovered that electrons
and beta particles were the same thing.Ernest Rutherford decided that radioactivity is
what caused atoms to be broken down.Ernest Rutherford and Hans Geiger discovered
that electrons moved around the nucleus of the
cell's atom much like planets orbit the sun.
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