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Ronalisa Arbis

on 12 May 2015

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Transcript of Timeline

History of the Atomic Theory
From humble beginnings....
What is the Atomic theory?
J.J. Thomson
scientific theory of the nature in matter
matter is composed of discrete units called
Greek adjective "atomos" meaning indivisible
Began in Ancient Greece-scientific mainstream in the early 19th century
The Plum Pudding
The Quantum Model of the Atom
Theory: That the atom is like plum pudding. The dotting on the dough are the electrons and the pudding itself is the positive charge.
pumped gas out of a glass tube that had two metal plates-electrode- on plate had a positive charge the other had a negative charge.
once the ray was turned on a beam was released, when the magnet was applied the ray was deflected
when the paddle wheel was applied the paddle wheel began to run
different materials and had the same result.
turning of the wheel shows beam had particles with mass
bending in the ray shows the particles in the beam have a negative charge
different metals with the same result show the negative charge particle is in all elements.
ending in the discovery of the electron
- Elaborated on Greek concept, laws of definite proportions, law of conversation mass, and law of multiple.
*1) Theory-Proposed that all matter was composed of atoms~Elements are composed of one atoms, compounds are composed of two or more atoms
2) Atoms of the given element are identical in physical and chemical properties
3) Atoms of different elements differ in physical and chemical properties
4) Atoms of different elements combine in simple, whole number ratios to for compounds
5) In chemical reactions, atoms are combined, separated, or rearranged, but never destroyed or changed

Error: Principle 1 and 2 are not always true in some cases. Today, scientists can divide atoms into smaller particles (protons, electrons, neutrons) and can destroy and create atoms
Dalton- 1803 A.D.
Democritus- 460 B.C.
"Could matter be divided into smaller and smaller pieces forever, or was there a limit to the number of time the pieces of matter could be divided?”
theory states that:
Matter could not be divided into smaller and smaller pieces forever
pieces would be indivisible.
“atomos,” meaning “not to be cut.”
1.)atoms were small, hard particles that were all made of the same material
2.)different shapes and sizes.
3.)Atoms were infinite in number, always moving and capable of joining together
Ernest Rutherford-1912
alpha particle: He +2
a beam of small, positively charged particles called alpha particles was directed at a thin gold foil
he conducted the alpha particle generator
the angles at which the particles were deflected from their former straight-line paths were measured by a team of scientists
deflections were a result of the alpha particles striking a more dense positively charged part of the atom called the nucleus
most of the alpha particles passed straight through the foil
very small number of particles were deflected; in some cases backward
because of the 'empty space' the nucleus was found to be very small, 1/10000 which is the radius of the whole atom
Mr. Flores approves of these theories!
Rutherford's student
theory: electrons have a stable orbit around the nucleus; an electron jumping can either absorb or releasing photon with a specific wave length.
experiment: hydrogen spectra
l = 2 orbital d (can hold up to 10e-)
l = 3 orbital f (can hold up to 14e-)
l = 0 orbital s ( can hold up to 2e-)
l = 1, l = -1 orbital p (can hold up to 6e-)
Special thanks to:
"Edmodo | File Preview." Edmodo | File Preview. N.p., n.d. Web. 06 Nov. 2013.
YouTube. YouTube, n.d. Web. 06 Nov. 2013.

Atoms can combine, separate, or rearrange with each other
His model was like a "billiard ball" model, saying you can't divide the atom into smaller pieces.
What to say Alisa: His theory is that the nucleus is small, densed, and charged. it's small because most of it the empty space & 1% hit the nucleus, & it's positively charged because that 1% bounced off, and since they have the same charges, it repels each other proving that it was positive.
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