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

460 – 370 BC

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Democritus proposes

the 1st atomic theory

460 – 370 BC

1743 – 1794

460 – 370 BC

History of the Atom - TimelineAntoine Lavoisier

makes a substantial number of contributions

to the field of Chemistry

1743 – 1794

460 – 370 BC

1743 – 1794

460 – 370 BC

1766 – 1844

1743 – 1794

460 – 370 BC

1766 – 1844

John Dalton proposes his

atomic theory in 1803

1743 – 1794

460 – 370 BC

1766 – 1844

1743 – 1794

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

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

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

Ernest Rutherford performs the Gold Foil

Experiment in 1909

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

1885 – 1962

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

1885 – 1962

Niels Bohr proposes the Bohr Model in

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

1885 – 1962

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

1885 – 1962

1887 – 1961

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

1885 – 1962

1887 – 1961

Erwin Schrodinger

describes the electron cloud in 1926

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

1885 – 1962

1887 – 1961

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

1885 – 1962

1887 – 1961

1891 – 1974

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

1885 – 1962

1887 – 1961

1891 – 1974

James Chadwick

discovered the neutron in in 1932

460 – 370 BC

1766 – 1844

1743 – 1794

1856 – 1940

1871 – 1937

1885 – 1962

1887 – 1961

1891 – 1974

Democritus(460 BC – 370 BC)

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

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• 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.

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• 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

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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.

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

• 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)

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

geotime2.html

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

Chemistry”

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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

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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

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

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

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• 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

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John Dalton (1766 – 1844)

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

• 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

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.

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)

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

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J.J. Thomson (1856 – 1940)

• Proved that an atom can be divided into smaller parts

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J.J. Thomson (1856 – 1940)

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

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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

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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

• Won a Nobel Prize

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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

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

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

• 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

Niels Bohr (1885 – 1962)

Image taken from: 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

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

Werner Heisenberg~1926

Quantum Mechanics

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

position of an electron at the same time

Microscope

Electron

Quantum Mechanics

Microscope

Electron

Quantum Mechanics

Microscope

Electron

Erwin Schrodinger (1887-1961)

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 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)

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• 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

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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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