Chapter one
lesson one : introduction of atomoic structure
to : Rutherford's atomic model objections.
Greek philospher:
imagined the possibility of dividing any piece of mater into smaller parts then divide these parts into smaller particles and so until we reach to
no dividable fragment.
it named Atom.
Greek language : A = No
Tom = divided
Aristotle:
- Rejected the Greek philosopher concept.
He believed that all matter whatever their nature are composed of 4 component;
water,air,dust and fire in diff. ratio which makes diff between matter.
You think :
you can change cheap metals like iron and copper into percious metals like gold and silver.
- He gave the first definition of element.
Element :
A pure substance that can not be changed to simpler form by simple chemical method.
He stated the first theory about the atomic structure.
Dalton's atomic theory:
1- the matter is composed of very minute particles called atom.
2- the atom is one solid and undividable.
3-the atom of each element are similar but the are diff from the atom of any other element.
Gases could conduct electricity under low pressure.
Cathode ray:
a stream of inadvisable ray emitting from cathode causing florescent glow on the tube wall of discharge tube with pressure 0.01 - 0.001 mm-Hg an high potential diff. 10.000 V.
Properties of anode rays:
- they consists of vey fine paricles.
- they move in a stright line.
they have a themal effect.
- they are negativly chaged.
- they are affected by electric and magnetic fields.
- they do not differ in behaviour or in nature if the cathode material is changed or the used gas.
This is a strong evidence the fundamental constituent of all matter.