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One - Two Terms

Atomicstructure - Summary
Atomic
structure

- Atom:
"A" means "no" and
"tom" means "divide".
- Aristotle: Believed that all matters are composed of four
componenets (water
– air – dust – fire).

- Boyle define the element as "a pure simple substance
that cannot be changed
to simpler forms by the traditional chemical methods".
- Dalton's atomic theorys –
the matter is composed of atoms which are undividable and each element have a certain type of
atoms.
- Cathode
rays: Consists of fine negative particles, move in
straight lines,
and have a thermal effect. They are affected by both electric and magnetic field. They do not differ in
behavior or in nature if the
material of the cathode or the used gas are changed. All element contain cathode rays.
- Thomson's
model: the atom is a sphere of a uniform positive electricity and
embedded in it equal number of –ve electrons. So, the atom is electrically neutral.

Rutherford's experiment:
1- The most of alpha)a)
particles hit the
same places, so, most of the atomic volume is empty sapce.
2- very small % of )a (particles did not penetrate the gold foil and reflected back, so, the
atom contain high
density nucleus.

3- A very small % of) a
( particles deflected, so the nucleus is positive charge.

Rutherford's Atom:
It is a vast space, its structure is similar to the
solar system.

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