Atomic Structure timeline
Category: Outro
Atualizado: 25 nov 2017
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Created byHillary Yip
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Eventos
John Dalton: Atomic Theory
He proposed the atomic theory and stated that
all matter is composed of small particles called
atom; atoms of a given element has an identical
size, mass and other properties; atoms cannot
be cannot be destroyed, subdivided or created;
in chemical reactions, atoms are separated,
combined or rearranged; and atoms of different
elements can combine in whole-number ratio to
form a chemical compound.Dmitri Mendeleev: Periodic Table
He organized the initial 63 elements into the
periodic table by the atomic mass. The format of
the rows and columns are still used today.G.J. Stoney: The electron
He calculated the magnitude of an atom and
proposed electricity was created by negative
particles called “electron”. This was supported
by the collection of data from the kinetic theory
of gas and electrolysis of water.Marie Curie: Radioactivity and new elements
She conducted experiments with uranium and
thorium to research about radioactivity and its
process of decay and also discovered two new
elements - polonium and radium. She is the first
person to win 2 Nobel Prizes and the first
female to win the prize.Ernest Rutherford: Radioactivity
Through the development of different innovative
techniques, He discovered two different
radioactive rays -alpha and beta. He also later
discovered the radioactive gas - radon.Ernest Rutherford: The Rutherford model
He proposed a model of the atom which
suggests that the atom contained a positively
charged nucleus which was surrounded by small
negatively charged elections. He came to this
conclusion from directing the famous Geiger-
Marsden experiment which is also known as the
gold leaf experiment. Alpha rays were aimed at
gold leaf but instead of passing through it, it was
repelled or emerged at different angles.H.G.J Moseley: Atomic Structure
He determined that "The atomic number of an
element is equal to the number of protons in
the nucleus". He also came to the conclusion
that there were 3 unknown elements (there are
actually 4 unknown ) between aluminium and
gold.Francis William Aston: Isotopes
With a mass spectrometer, he discovered the
existence of isotopes and created the “whole
number rule” which states “the masses of the
isotopes are whole number multiples of the
mass of the hydrogen atom”Niels Bohr: Atomic Structure
He proposed a theory suggesting that how
electrons are able to stably orbited the nucleus
and stating that electrons have to move in a
fixed energy and size. This theory is a modified
version of Rutherford’s model.James Chadwick: The Neutron
Through experimenting with Beryllium by
projecting alpha particles towards it and
“filtering” it through paraffin wax, he discovered
a particle that did not consist of a charge, which
he named “neutron”The Standard Model:
The current model of the atom states that an
atom consists of electrons orbiting the nucleus
which exist in the electron shell. The electron is
negatively charged. The nucleus consists of
protons and neutron and the proton is
positively charged whilst the neutron has no
charge.
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