Scientists And Their Contributions To The Atomic Theory
Published on Nov 18, 2015
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PRESENTATION OUTLINE
ATOMIC THEORY
By: Jihan Khalaf
HISTORICAL DEVELOPMENT
- The philosophy of atomism developed in many ancient traditions.
- Greek philosophers purposed the existence of atoms.
JOHN DALTON
- scientists background: He was born on september 6, 1766 in England.
- John was a chemist, Meteorologist, and a Physicist.
- 1800, he was secretary of the Literary and Philosophical society.
- He developed the Dalton’s Law in 1801.
- Law: total pressure = sum of partial pressures of gases.
DESCRIPTION OF EXPERIMENTAL DESIGN
- Dalton printed his first published table on atomic weights.
- In his laboratory notebook, he made a list setting out the atomic weights of elements.
- problem of calculation was made that: the proportionate diameter of the atoms in which he was persuaded that all gases were made.
- Dalton used chemical analysis, which is the quantity, separation, and identification of chemical parts or elements.
- Procedures: John Dalton did not use any procedures, instead he used calculations, laws, physics, and mathematics to come up with his theory.
DATA COLLECTED
- 1. Energetic mountain excursions (movement of a body or a point from a mean position to a neutral value)
- 2. Investigated if water vapor existed separately in the atmosphere.
- Analysis/conclusions: He concluded that water vapor exists in air as the only gas.
JJ THOMPSON
- Background: he was a British physicist who was born on December 18, 1856 in Manchester, England.
- He found the first evidence of isotopes.
- Contribution:
- 1. Thompson discovered the natural radioactivity of potassium (K) in 1905.
- 2. 1906: determined that hydrogen had only one electron per atom.
EXPERIMENTAL DESIGN
- he was the first one who investigated the magnetic bend of cathode rays.
- A Cathode Ray is a flow of electrons from a cathode(electrode) in a vacuum tube and into a narrow beam.
- Procedures:
- In his experiment Thompson used tools such as: Crookes tube, electrometer, and a magnet.
- He did experiments to show how cathodes were charged and bent electrically.
DATA COLLECTED
- he found out that the mass to charge ratio was 1,000 times lower than the mass-charge ratio of hydrogen.
- Analysis/conclusions:
- 1. The cathode rays carried negative charge of electricity.
- 2. Imagined the atoms being made up of small particles of matter orbiting in a group of positive charges.
EARL RUTHERFORD
- Background: he was born on August 30, 1871 in New Zealand. He was a Physicist and chemist.
- Rutherford became known as the father of nuclear physics ( studies the components and interactions of the atomic nucleus.
- Contribution:
- 1911, he theorized that atoms have their charge focused in a very small nucleus.
EXPERIMENTAL DESIGN
- Rutherford presented the Rutherford gold foil experiment which demonstrated the nuclear nature of atoms.
- Procedures:
- The experiment included the firing of radioactive particles through gold.
- He used a scintillator ( screen coated with zinc sulfide).
NEILS BOHR
- Background: he was born on October 7, 1885 in Denmark.
- He was a Denmark Physicist who made contributions to understanding the atomic structure and his creation of the quantum Theory.
- Contribution;
- 1913, Bohr developed the Bohr model (shows the atom as small with a positively charged nucleus surrounded by an electron).
IRENE CURIE
- Background: She was a French scientist, born on September 12, 1897 in Paris France.
- She discovered the artificial radioactivity and won a noble prize.
- Contribution:
- 1924, she taught the correct laboratory techniques for radiochemical research.
ROBERT MILIKAN
- Background: Milikan was born on March 22, 1868 in Illinois, U.S.
- He was a physicist who won a noble prize for physics.
- Contribution:
- In 1923 he measured the elementary electronic charge which was also known as the electric charge.
