Download Atomic Models

Atomic Models throughout history
Models to represent the
of the atom have changed over time.
was an ancient Greek philosopher who was born in 460BC. He
described matter as being made up of indivisibles (
name
came from. In
). This is where the
, atomis means uncuttable.
The ancient Greeks adopted the belief that all matter is made up of Earth, Water, Fire and Air.
Ideas about atoms and their structure didn’t change much for almost
In 1808, an English chemist, John
years.
described matter. He believed
matter is made up of
, indivisible (unable to be divided ….NOT
invisible) particles which he calls atoms. Joseph J Thomson, an English
, described atoms like a plum pudding. The description was known as the plum
model. In this model atoms were presented as having a heavy
positive pudding with the light negatively charged
embedded in it.
The discovery of radioactivity allowed scientists to examine atoms in
Rutherford used radio active
ways. Ernst
to find out that atoms had a tiny,
very dense, positively charged nucleus with electron
the nucleus. He concluded that atoms contained mainly
physicist, Niels Bohr improved on Rutherford’s model in
electrons in orbits with definite
discovered and identified the
space. The Danish
.
Bohr’s
model
has
and amounts of energy. James Chadwick
. The neutron is a neutral particle found in the
nucleus.
In 1932, a new atomic model was developed. It was developed using
ideas
about atoms and the work of several new scientists. The model indicated that most of an
atom’s mass is in the
.
and
neutrons
are
found in the nucleus. The electrons can be found in very definite areas around the nucleus
but are constantly
. The Standard Model is the commonly used
atomic model in modern science. It is based on the previous model but has more
arrangements of electrons around the atoms.
Word List……
Previous, 2000, new, solid, neutron, complex, electrons, Democritus,
pudding, atom, Protons, Greek, orbiting, empty, Dalton, structure,
atomis, 1913, physicist, particles, nucleus, positions, moving.