Five Landmark Chemistry Experiments of Atomic Theory

Rutherford's Gold Foil Experiment

Bohr's Model

Bohr Model

Overview of the Gold Foil Experiment

And the final overview to end off the Atomic Theory.

End

Niels Bohr created this model based off of Rutherford's experiment. The model shows that atoms have a positively charged nucleus (protons and neutrons) that is surrounded by negatively charged electrons in a ring. The Bohr Model basically finalized the atomic theory by giving a model of how an atom looked with its protons, neutrons, and electrons. A strength of his experiment was that it proved the existence of electrons orbitting around a nucleus. Despite this, his model also makes poor predictions regarding larger atoms and doesn't predict the relative intensities of spectral lines.

Millikan's Oil Drop Experiment

Rutherford's Gold Foil Experiment

Overview of the Oil Drop Experiment

Robert A. Millikan and Harvey Fletcher used this model to measure the specific charge of an electron. The experiment involved ionizing droplets of oil while falling through the air. This experiment contributed to society by finding a relatively close approx. of the charge of an electron. His experiment determined the charge of an electron and gave convincing proof that subatomic particles existed. A weakness of his experiment was that it wasn't able to accurately measure the charge of an electron, although it was close.

According to Ernest Rutherford, his experiment demonstrated that a majority of an atom is empty space while the center includes a nucleus. Rutherford's experiment involved shooting particles through a thin sheet of gold. A majority of the particles passed through, but some of the particles were reflected back. Rutherford concluded that the mass of an atom is concentrated in the middle. Rutherford contributed to the atomic theory by proving that atoms had a nucleus at the center and that it wasn't just empty space. The experiment concluded that an atom was more than just empty space and an atom must have a postively charged nucleus, which were some of the strengths. A weakness of his experiment is due to Rutherford not knowing exactly what alpha particles were when shooting them at the sheet of gold.

J.J. Thomson's Cathode Ray Tube Experiment

Overview of the Cathode Ray Tube Experiment.

Thomson's Cathode Ray Tube Experiments

J.J. Thomson's experiment proved that negatively charged electrons existed. He proved the existence of electrons with cathode ray tubes. His experiment provided evidence supporting Dalton's postulates. This experiment also allowed for the invention of the florescent light bulb. This contributed to a newer atomic theory by discovering that electrons had a negative charge and concluded that atoms were divisible. The strengths of his experiment include further supporting Dalton's theory and concluded that electrons had a negative charge. J.J. Thomson said that an electron had a charge, but he didn't explain the structure of the electron, which weakened his experiment.

John Dalton

John Dalton, himself created this atomic theory. He came up with these postulates after experimenting with gases. These experiments tried to find the law of definite and indefinite proportions of gases. His atomic postulates allowed for society to have a basis for experimentation on the atomic theory. John Dalton's experiment gave clear evidence for his postulates and he was able to repeat the experiment. Although the experiment gave proof to many things, there were some things that were wrong. Statements like "atoms were the smallest units of matter" and "atoms were indivisible" undermined his theory.

Dalton's Atomic Theory

Dalton's Postulates:

• All matter is made up of atoms that are indivisible and indestructible.
• All atoms of one element are identical in mass and properties.
• Compounds are formed by a combination of two or more different kinds of atoms.
• A chemical reaction is a rearrangement of atoms.

Five Landmark Chemistry Experiments of Atomic Theory

The modern atomic theory is a theory that all matter is composed of tiny particles called atoms. This theory is used in physics and chemistry to explain the behavior of all matter.

By: Brian Tran