History of the Atomtheory 460 – 370 BC History of the Atom - Timeline 0 1700s 1800s 1900s ... all...

History of the AtomScientists and Their Contribution to

the Model of an Atom

Tuesday, October 8, 13

History of the Atom - Timeline

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Democritus proposes

the 1st atomic theory

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History of the Atom - TimelineAntoine Lavoisier

makes a substantial number of contributions

to the field of Chemistry

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John Dalton proposes his

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J.J. Thomson discovers the electron and proposes the Plum Pudding Model in 1897

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Ernest Rutherford performs the Gold Foil

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Niels Bohr proposes the Bohr Model in

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Erwin Schrodinger

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James Chadwick

discovered the neutron in in 1932

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Democritus(460 BC – 370 BC)



Image taken from: https://reich-chemistry.wikispaces.com/T.+Glenn

+Time+Line+Project


https://reich-chemistry.wikispaces.com/T.+Glenn+Time+Line+Project







• Proposed an Atomic Theory (along with his mentor Leucippus) which states that all atoms are small, hard, indivisible and indestructible particles made of a single material formed into different shapes and sizes.


+Time+Line+Project









• Proposed an Atomic Theory (along with his mentor Leucippus) which states that all atoms are small, hard, indivisible and indestructible particles made of a single material formed into different shapes and sizes.

• Aristotle did not support his atomic theory


+Time+Line+Project








Some Early Ideas on Matter


Anaxagoras (Greek, born 500 B.C.)–Suggested every substance had its own kind of “seeds” that clustered together to make the substance, much as our atoms cluster to make molecules.





Empedocles (Greek, born in Sicily, 490 B.C.)–Suggested there were only four basic seeds – earth, air, fire, and water. The elementary substances (atoms to us) combined in various ways to make everything.





Democritus (Greek, born 470 B.C.)–Actually proposed the word atom (indivisible) because he believed that all matter consisted of such tiny units with voids between, an idea quite similar to our own beliefs. It was rejected by Aristotle and thus lost for 2000 years.





Democritus (Greek, born 470 B.C.)–Actually proposed the word atom (indivisible) because he believed that all matter consisted of such tiny units with voids between, an idea quite similar to our own beliefs. It was rejected by Aristotle and thus lost for 2000 years.

Aristotle (Greek, born 384 B.C.)–Added the idea of “qualities” – heat, cold, dryness, moisture – as basic elements which combined as shown in the diagram (previous page). Hot + dry made fire; hot + wet made air, and so on.


Alchemy


Alchemy

• After that chemistry was ruled by alchemy.

• They believed that they could take any cheap metals and turn them into gold. This is called transmutation.

• Alchemists were almost like magicians.– elixirs, physical immortality


Contributionsof alchemists:



Information about elements



Information about elements - the elements mercury, sulfur, and antimony were discovered



Information about elements - the elements mercury, sulfur, and antimony were discovered- properties of some elements




Develop lab apparatus / procedures / experimental techniques




Develop lab apparatus / procedures / experimental techniques - alchemists learned how to prepare acids.




Develop lab apparatus / procedures / experimental techniques - alchemists learned how to prepare acids. - developed several alloys




Develop lab apparatus / procedures / experimental techniques - alchemists learned how to prepare acids. - developed several alloys - new glassware


Antoine Lavoisier (1743 – 1794)


Antoine Lavoisier (1743 – 1794)

Image taken from: www.ldeo.columbia.edu/.../v1001/

geotime2.html


http://www.ldeo.columbia.edu/.../v1001/geotime2.html




Antoine Lavoisier (1743 – 1794) • Known as the “Father of Modern

Chemistry”


geotime2.html







Chemistry”• Was the first person to generate a list of

thirty-three elements in his textbook


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thirty-three elements in his textbook• Devised the metric system


geotime2.html








thirty-three elements in his textbook• Devised the metric system• Was married to a 13-year old Marie-Anne

Pierette Paulze; she assisted him with much of his work


geotime2.html










• Was a tax-collector that was consequently guillotined during the French Revolution


geotime2.html











• Discovered/proposed that combustion occurs when oxygen combines with other elements


geotime2.html











• Discovered/proposed that combustion occurs when oxygen combines with other elements

• Discovered/proposed the Law of Conservation of Mass (or Matter) which states, in a chemical reaction, matter is neither created nor destroyed


geotime2.html






John Dalton (1766 – 1844)



Image taken from: chemistry.about.com/.../John-

Dalton.htm


http://chemistry.about.com/od/historyofchemistry/ig/Pictures-of-Famous-Chemists/John-Dalton.htm





• In 1803, proposed an Atomic Theory which states:


Dalton.htm







• In 1803, proposed an Atomic Theory which states:o All substances are made of atoms;

atoms are small particles that cannot be created, divided, or destroyed.


Dalton.htm









o Atoms of the same element are exactly alike, and atoms of different elements are different


Dalton.htm










o Atoms join with other atoms to make new substances


Dalton.htm











• Calculated the atomic weights of many various elements Image taken from:

chemistry.about.com/.../John-Dalton.htm


http://www.meta-synthesis.com/webbook/35_pt/pt_database.php?PT_id=5











• Calculated the atomic weights of many various elements

• Was a teacher at a very young age


Dalton.htm













• Calculated the atomic weights of many various elements

• Was a teacher at a very young age • Was color blind


Dalton.htm




http://colorvisiontesting.com/

http://colorvisiontesting.com/





Dalton’s Atomic Theory (1808)



1. All matter consists of tiny particles. Dalton, like the Greeks, called these particles “atoms”.




2. Atoms of one element can neither be subdivided nor changed into atoms of any other element.





3. Atoms can neither be created nor destroyed.






4. All atoms of the same element are identical in mass, size, and other properties.







5. Atoms of one element differ in mass and other properties from atoms of other elements.







6. In compounds, atoms of different elements combine in simple, whole number ratios.

5. Atoms of one element differ in mass and other properties from atoms of other elements.


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Dalton’s symbols, 1808


Dalton’s atomic weights, 1808


• Michael Faraday (1825)- Split compounds by electrolysis and showed that atoms have electrical properties

• 1833 Michael Faraday discovers quantitative laws of electrochemical deposition.

• He introduces the terms electrode, cathode, anode, ion, anion, cation, electrolyte.

• He establishes that a definite quantity of electricity is associated with each atom of 13

Michael Faraday(1791-1867)


J.J. Thomson (1856 – 1940)


J.J. Thomson (1856 – 1940)

Image taken from: www.wired.com/.../news/2008/04/

dayintech_0430


http://www.wired.com/.../news/2008/04/dayintech_0430




J.J. Thomson (1856 – 1940)

• Proved that an atom can be divided into smaller parts


dayintech_0430






J.J. Thomson (1856 – 1940)


• While experimenting with cathode-ray tubes, discovered corpuscles, which were later called electrons


dayintech_0430


http://library.thinkquest.org/28582/history/qmexp.htm






J.J. Thomson (1856 – 1940)



• Stated that the atom is neutral


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J.J. Thomson (1856 – 1940)



• Stated that the atom is neutral• In 1897, proposed the Plum Pudding

Model which states that atoms mostly consist of positively charged material with negatively charged particles (electrons) located throughout the positive material


dayintech_0430








J.J. Thomson (1856 – 1940)



• Stated that the atom is neutral• In 1897, proposed the Plum Pudding

Model which states that atoms mostly consist of positively charged material with negatively charged particles (electrons) located throughout the positive material

• Won a Nobel Prize


dayintech_0430








Discovered by J.J. Thomson. He said the atom was a

sphere of positive electricity, with negative particles throughout. This came around right after he

discovered the electron.Tuesday, October 8, 13

http://wind.cc.whecn.edu/~mechalke/chapter5/Chapter5.htm

http://wind.cc.whecn.edu/~mechalke/chapter5/Chapter5.htm

He was by far the most famous American scientist. He wanted to find the electrical charge of electrons. He measured water droplets, and that wasn’t successful, so he measured oil droplets, where all this proved electrons were negatively charged. He also was a professor for many years, and wrote many textbooks on chemistry.

http://www.chemistryexplained.com/images/chfa_03_img0536.jpg

Robert Millikan




• Robert Millikan (1868-1923)– Oil drop experiment – 1909


Ernest Rutherford (1871 – 1937)



Image taken from: http://www.scientific-web.com/en/Physics/Biographies/ErnestRutherford.html


http://www.scientific-web.com/en/Physics/Biographies/ErnestRutherford.html







• In 1909, performed the Gold Foil Experiment and suggested the following characteristics of the atom:



http://www.micro.magnet.fsu.edu/electromag/java/rutherford/index.html











• In 1909, performed the Gold Foil Experiment and suggested the following characteristics of the atom:o It consists of a small core, or nucleus,

that contains most of the mass of the atom
















o This nucleus is made up of particles called protons, which have a positive charge

















o The protons are surrounded by negatively charged electrons, but most of the atom is actually empty space


















• Did extensive work on radioactivity (alpha & beta particles, gamma rays/waves) and was referred to as the “Father of Nuclear Physics”



















• Won a Nobel Prize• Was a student of J.J. Thomson



















• Won a Nobel Prize• Was a student of J.J. Thomson • Was on the New Zealand $100 bill













Gold-Foil Experiment

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Niels Bohr (1885 – 1962)


Niels Bohr (1885 – 1962)

Image taken from: commons.wikimedia.org/wiki/

File:Niels_Bohr.jpg


http://commons.wikimedia.org/wiki/File:Niels_Bohr.jpg




Niels Bohr (1885 – 1962)

• In 1913, proposed the Bohr Model, which suggests that electrons travel around the nucleus of an atom in orbits or definite paths. Additionally, the electrons can jump from a path in one level to a path in another level (depending on their energy)


File:Niels_Bohr.jpg


http://www.colorado.edu/physics/2000/quantumzone/bohr.html






Niels Bohr (1885 – 1962)




File:Niels_Bohr.jpg








Niels Bohr (1885 – 1962)


• Won a Nobel Prize • Worked with Ernest Rutherford


File:Niels_Bohr.jpg








Quantum Mechanics

Microscope

Electron

γ

Werner Heisenberg~1926


http://en.wikipedia.org/wiki/Werner_Heisenberg





















Quantum Mechanics

• Heisenberg Uncertainty Principle– Impossible to know both the velocity and

position of an electron at the same time

Microscope

Electron

γ

Werner Heisenberg~1926























Erwin Schrodinger (1887-1961)



Image taken from: nobelprize.org/.../1933/schrodinger-

bio.html


http://nobelprize.org/nobel_prizes/physics/laureates/1933/schrodinger-bio.html





• In 1926, he further explained the nature of electrons in an atom by stating that the exact location of an electron cannot be stated; therefore, it is more accurate to view the electrons in regions called electron clouds; electron clouds are places where the electrons are likely to be found Image taken from:

nobelprize.org/.../1933/schrodinger-bio.html







• In 1926, he further explained the nature of electrons in an atom by stating that the exact location of an electron cannot be stated; therefore, it is more accurate to view the electrons in regions called electron clouds; electron clouds are places where the electrons are likely to be found

• Did extensive work on the Wave formula Schrodinger equation


bio.html







• In 1926, he further explained the nature of electrons in an atom by stating that the exact location of an electron cannot be stated; therefore, it is more accurate to view the electrons in regions called electron clouds; electron clouds are places where the electrons are likely to be found

• Did extensive work on the Wave formula Schrodinger equation



bio.html






James Chadwick (1891 – 1974)




dayintech_0227







• Realized that the atomic mass of most elements was double the number of protons discovery of the neutron in 1932


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• Worked on the Manhattan Project


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• Worked with Ernest Rutherford


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• Worked with Ernest Rutherford• Won a Nobel Prize


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Progression of the Atomic Model

The structure of an atom, according to:




Democritus & John Dalton




J.J. Thomson

+-- --

- -




Ernest Rutherford




Neils Bohr




Erwin Schrodinger




James Chadwick


History of the Atomtheory 460 – 370 BC History of the Atom - Timeline 0 1700s 1800s 1900s ... all...

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