Atomic Theory Scientists

Dalton's Atomic Theory

All matter (tennis ball) has atoms in it

Experiments and Discovery

Dalton's Atomic Theory had 4 points

1. All matter is made up of atoms

2. Atoms are unbreakable

3. Atoms of a given element are the same

4. Atoms come together in whole-number ratios to form compounds

Dalton discovered this theory with his previous experiments he did with gas that led to his Law of Partial Pressures.

Strengths and Weaknesses

Strengths

1. It explains the Laws of Chemical Composition and the Law of Multiple Proportions

2. Dalton found the difference between an atom and a compound

Weaknesses

1. Dalton's idea that an atom w/ the same elements are identical is not true because there are isotopes (different # of neutrons)

2. His theory that atoms are indivisible has been found to be false because it can be subdivided into protons, neutrons, and electrons

• On April 30, 1803 the Louisiana Purchase was made by the United States from France.

• On June 9th Matthew Flinders completes the first known circumnavigation of Australia.

History Outlook

• William Hyde Wollaston discovered the element rhodium.

Experiments and Discoveries

J.J. Thomson discovered that atoms have negatively charged particles (electrons) that are deflected by an electromagnetic field. The experiment this resulted from was the Cathode Ray Tube Experiment.

Thomson also determined the charge-mass ratio; if there are negative parts then there positive parts in order to keep them together.

Strengths

1. The Cathode Ray shows that there are negatively charged subatomic particles called electrons.

2. The Plum Pudding model shows in a simple way how the nucleus stays together without coming apart.

Weaknesses

1. The Plum Pudding model doesn't account for the nucleus or subatomic particles other than the electron.

Strengths and Weaknesses

• San Diego State University was founded. (SDSU, CA) on March 13th.

History Outlook

• April 19, 1897 the first Boston Marathon was held.

• The sorority Kappa Delta was created in October 23, 1897.

Experiment and Discovery

Rutherford in his gold foil experiment shot a beam of alpha particles towards a sheet of gold foil. A few of these particles were deflected. He then concluded that a small, dense nucleus was the cause of the deflections.

Rutherford also discovered the alpha and beta rays as well as proposed the laws of radioactive decay.

Strengths and Weaknesses

Weaknesses

1. The orbital revolution of an electron is not stable and loses energy. This would make them slow down and go towards the nucleus.

2. Rutherford couldn't explain how electrons remain in orbit when they should fall into the positively charged nucleus.

Strengths

1. The gold foil experiment could tell us that the atom has a positive charge since the nucleus has protons (positive) and neutrons (neutral).

2. Rutherford worked with other big name scientists to form these conclusions.

3. The particles during the experiment were able to go through the foil w/o anything deflecting their path

• The White Socks threw the World Series. The Cincinnati Reds won the Series.

• On May 21, 1919 Women got the right to vote in the 19th amendment.

History Outlook

• Theodore Roosevelt had his funeral in 1919

Experiment and Discovery

Chadwick put beryllium atoms into a vacuum chamber with alpha particles (polonium) to create an unknown radiation. Chadwick said this radiation was made of particles with a neutral electric charge. He then called it a neutron.

In 1932, scientists like Chadwick used a particle detector to prove the nucleus has protons and neutrons.

Strengths

1. The discovery of the nucleus was used to make the atomic bomb.

2. The discovery helped Niels Bohr make the first theoretical representation of the atom.

Weaknesses

1. There were very few weaknesses

Strengths and Weaknesses

• Franklin D. Roosevelt beat Herbert Hoover in the election for President.

• The Great Depression was going on during this time period.

History Outlook

• A hurricane and huge waves killed about 2,500 in Santa Cruz del Sur.

Experiment and Discovery

During WWII, Fermi became a leader on the Manhattan Project which was focusing on the development of the atomic bomb.

Enrico Fermi conducted the first controlled chain reaction releasing energy from atoms nucleus. One of the first elements he split was Uranium. This helped him discover the slowing down of neutrons which led to nuclear fission.

Strengths and Weaknesses

Strengths

1. He discovered that any element can undergo nuclear transformation.

2. He worked with quantum mechanics to solve problems with atomic physics.

Weaknesses

1. Making the bomb was a battle of his morals. He knew it would help the U.S. but that it would also ruin entire cities.

• The U.S. dropped the Atomic Bomb on Japan's main islands.

History Outlook

• Women's Coast Guard Auxiliary was established

• The minimum draft age is lowered from 21 to 18.