The Atomic Theory of Matter

1
The Atomic Theory of Matter

• By Shaffer Lisle

2
The First Theories

• John Daltons proposed theories
• Each element is composed of particles called
  atoms.
• All atoms in an element have identical mass and
  other properties. Atoms of one element are
  different from that of another element.
• Atoms are not changed into atoms of a different
  element by chemical reactions they are neither
  changed nor destroyed during chemical reactions.

3
John Daltons Theory and Its Change

• John Daltons theory says that atoms are the
  smallest particles that still retain chemical
  identity of an element.
• With new technology we have found subatomic
  particles within atoms.
• A lot of things are still considered correct with
  John Daltons theory even today.

4
The Discovery of the Electron

• The electron was found when scientists started to
  study cathode ray tubes.
• Cathode ray tube pumped almost empty of air
  (vacuum tube).
• A high voltage produces radiation within the
  tube. The radiation is known as cathode rays
  because it comes from the negative electrode or
  cathode.

5
The Discovery of the Electron

• There were conflicting views about cathode rays.
  It wasnt clear whether they were a stream of
  particles or a form of radiation. Experiments
  showed that they were deflected by electric or
  magnetic fields in a consistent way of their
  being a stream of negative charge. The British
  Scientists J.J. Thomson observed that the rays
  stayed the same regardless of the cathode
  material. His discoveries were considered the
  discovery of the electron.

6
Subatomic Particles

• The rest of the subatomic particles were found
  when scientists made theories on where the
  electrons were in an atom. In 1910, a scientist
  named Rutherford examined the effects of passing
  alpha rays through a gold foil a few thousand
  atoms thick. He found that most passed right
  through the gold foil while some were deflected.
  This was later concluded that there is a lot of
  empty space in an atom and that they mostly
  passed through the empty space ,sometimes getting
  deflected by the later discovered nucleus (made
  up of protons and neutrons).

7
The Modern Atomic Structure

• The modern atomic structure is mainly the protons
  and neutrons in the nucleus, with electrons
  moving in the open space in the atom.

8
The End
By Shaffer Lisle