Post on 12-Jul-2015
H O W T H E A T O M W A S O N C E I D E A L I Z E D T OB E K N O W N A S W E K N O W I T T O D A Y ?
Atomic theory
Chemistry 1
Etymology
Indian Greek
By the end of 2nd centuryB.C. Kanada believedthat matter was composedby “Atoms” grouped intomore complexed objects.
By the 5th century B.C. Democritus stated that smallparticles called “Atoms” werepresent in all types of matterand their constantly changingtheir arrange.
Philosophical atomism
Ishvara Democritus
E X P E R I M E N T A L E V I D E N C E S H O W S N E W I D E A S A B O U T A T O M S A N D C O M P O U N D S
Modern Atomic Theory
Modern Atomic theory
1789 and 1799 laws by Lavoisier and Proust
1808 Atomic model by John Dalton
1897 J.J Thomson the “Plumb Pudding”
1909 Ernest Rutherford discovered the nucleus
1913 Niels Bohr “The Bohr model”
1918 Rutherford “strikes again” with the protons
1932 James Chadwick and the neutrons
1924 Louis de Broglie and the orbitals
Two fundamental laws appear
1789 Antoine Lavoisier stablished the “Law of conservation of mass”
1799 Joseph Proust stablished the “law of definiteproportions”
Joseph Proust
Antoine Lavoisier
Two fundamental laws appear
“Law of conservation of mass”
“Law of definite proportions”
1808 Dalton´s Theory
“chemical element is composed of atoms of a single, unique type, and they cannot be altered or destroyed by chemical means, they can combine to form more complex structures”
John Dalton
Dalton Theory
The Subatomic particles age
By 1887 J.J. Thomson breaks down the idea thatthe atom was undivisible and discovers theELECTRONS
J.J. Thomson
The Plumb Pudding
Positive charged cloud
Negative charged corpuscles
Ernest Rutherford Model
By 1909 Rutherford working with alfa particlesdiscovered the positive charged nucleus of the atomand stablished the “Planetary model”
Ernest Rutherford
The Rutherford experiment
Thompson Model
Rutherford Model
Alfa particlesheavily
deflected
The “Planetary Model”
Nucleus
Electron cloud
The Bohr reafirmation
At 1916 Niels Bohr based on the “Quantum theory” justify the steady orbit of the electrons and stablishthat orbitals of diferent levels of energy surround thenucleus and electrons move around them
Niels Bohr
Niels Bohr and Albert Einsten
The Bohr Atomic model
Bohr atomic model
Building the nucleus, Rutherford strikes again!
In 1918, Rutherford bombarded nitrogen with alfa particles, analyzing and realizing that he succesfullydivided the nucleus into smaller positive chargedparticles called: “Protons”
Ernest Rutherford at 1918
Case pending
Protons didn´t complete the weight of the nucleus by themselves
Rutherford suggest that this mass couldbeen completed in the nucleus by
particles without charge
Discovery of neutrons
Walther Bothe by 1928 discovers that Beriliumemitted neutral charged beams when bombed withalfa particles.
James Chadwick finds neutral beams to be particleswith a similar mass of a proton.
Walther BotheJames Chadwick
The Atom
So, this is the Atom, as we know now.
Electron
Nucleus with sameproportion of Neutrons
and protons
Electronic orbitals