2.2 (a) Atomic model.ppt

students….

HOW DOES ATOM LOOK LIKE?

DOES IT SIMILAR TO TINY BALL?

Atom is the basic block of matter.

HOWS THE TINY BALL LOOK LIKE?

IS IT LIKE THIS???

YES NO

Development of Atomic Models

Scientists Involved in the Development of Atomic Model :

John DaltonJ.J ThomsonErnest RutherfordNeils BohrJames Chadwick

DO YOU KNOW?

OVER 100 YEARS, SCIENTIST HAVE DONE INVESTIGATIONS WHICH SHOW THE ATOM ARE

NOT SOLID. ATOMS ARE MADE UP OF SMALLER

PARTICLES.

John Dalton

Imagined the atom as a small indivisible ball, similar to a very tiny ball

All the atom of any one element are identical: they have the same mass and same chemical properties.

J.J Thompson

•Discovered electron.

•Described the atom as sphere of positive charge which contains a few negatively charged particles.

•The negatively charged particles called electrons.

Ernest Rutherford

Discovered proton. Proton is positively

charge in an atom. The positive charge and

most of the mass of atom concentrated in a small, central region called the nucleus.

Electrons moves in a space that is larger than the space occupied by the nucleus.

proton

electron

Neils Bohr

An electron in an atom move in shells around the nucleus .

James Chadwick

Proved the existence of neutrons.

Neutron are neutral particles in the nucleus.

Neutron contribute approximately to half the mass of an atom.

THE DEVELOPMENT OF ATOMIC MODEL

John Dalton

Ernest Rutherford

Neils Bohr

James

Chadwick

ATOMIC STRUCTURE