Chapter one

Structure of the
atom

Atomic structure

 

1-
Greek philosophers:

     Any piece of matter can be divided into
smaller parts and each part can be subdivided into smaller parts which can't be
divided this part is called Atom.

 

2- Aristotle

a-He refused the idea of Greek philosophers
about the atom .

 

b- He supposed that all matters composed of
4 constituents which are ( water, air ,dusta and fire and postulated
that the cheap metals such as iron or copper can be changed into precious ones
like gold by changing the percentage of fourconstituents.

 

3- Boyl ( lrish 1661 )

 

i-He refused the Aristotle concept.

ii-He was the 1^st scientist to
define the element as pure simple substance which can

   not
be analvsed into smple one by normal chemical methods.

 

4) Dulton 
s atom ( Englsh 1803 )

    He
supposed thet :

<!--[if !supportLists]-->1-    The substance consists of very amall
particles called atoms.<!--[endif]-->

<!--[if !supportLists]-->2-    Every element consists of very small
dense atoms which can t be divided.<!--[endif]-->

<!--[if !supportLists]-->3-    Atoms f the same element are identical.<!--[endif]-->

<!--[if !supportLists]-->4-    Atome of different are different.<!--[endif]-->

 

 

N.B  By the 19 th century

      
Scientists had accepted the idea that elements consists of atoms but
they knew very little about those atoms.