-
Democritus 430 B.C.
-He proposed that matter is madae of tiny particles called atoms also everything else is made of matter.
-He relied on rational processes rather than experimental observation.
-He believed that atoms of the different elements may have different shapes.
-www.google.com -
Dalton 1800 A.D
-He discovered that the atoms were tiny invisible, indestructable particles.
-He used obervation evidence to guide his theories, hypothesis, and predictions.
-Nicknamed- Billards ball model because he thought that the atoms looked like billards ball from the game pool.
www.google.com
-google.com -
Thomson 1898 A.D
-he discovered that electricity passing through a gas could the gas to give particles that were too small to be atoms
-He used the property of cathrode rays
-He thought the atom looke like a small sphere nicknamed plum pudding and raisin bread
-web.lemonye.edu
--web.lemoyne.edu -
Rutherford 1911 A.D
-Adiffuse cloud of negatively charged electrons surrounding small, dense, positively charged nucleus
-By using the gold foil experiment
-He suggested that the atom consisted of small dense core of positively charged particles int he center of the atom surrounding my a swirling ring of electrons
-www.britannica.com
-www.britianna.com -
Bohr 1913 A.D
-He discovered energy levels of electrons are discrete and the electrons revovle in stable orbits around the atomic nucleus but can jump from one energy level to another
-He made his discovery by performing numerous experiments on the element hydrogen
-The electrons could only have certain classical motion; small positively charged nucleus orbited by negatively - charged electrons
-chemistry.about.com
-www.idu.edu -
Heisenburg and Schrodinger 1927 A.D.
-He discovered the atom with the neutons electron cloud
-The eHeisenburg uncertainly relationship mathematical equation was the method
-They thought it looked round with protons and neutrons surrounded by an electron cloud
-www.iun.edu
