Niels Henrik David Bohr

Danish Physicist

Background of Neils Bohr

Neils Bohr was born in October 7th, 1885. He was a Danish Physicist who made contributions to the atomic structure and the quantum theory. He then received the Nobel Prize for physics in 1922.

Experimental Design

Niels Bohr came up with a design, or model, to explain how elements differ form each other. He invented the Bohr model. The middle of the model is the nucleus, which consists of protons and neutrons. The outer shells outside of the nucleus are where the electrons are placed. The number of shells is determined by the number of electrons the element contains. The design Niels Bohr invented is still used today.
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Evidence leading to a change in the Atomic Model.

The previous model of the atom was there were orbits around the nucleus and electrons would travel on the orbits. They inferred that the electron distance was random and they travel as if they were orbiting the sun. The structure was showed so that as an electron would lose energy it would get closer to the nucleus. The example used was hydrogen when heated. When heated it would produce a spectrum of continuous colors and then go back towards the nucleus when cooled. However, it was later discovered that hydrogen only produced certain colors. Also, James Clark Maxwell showed that a hydrogen atom would run out of energy and eventually run into the nucleus. Mr. Bohr knew this wasn't correct. To account for this, Neils Bohr created his model.
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Resolution of the Previous Flaw

Bohr’s model would consist of many orbits around the nucleus. However, his model showed that electrons didn’t travel in between orbits, but jumped and skipped from orbit to orbit. Each orbit can hold a certain amount of electrons and can be determined by Bohr’s equation 2 x n^2. N means what orbit shell it is with shell one being closest to the nucleus. Bohr stated that when electrons gain energy, they get excited and jump orbit shells. This resolved the flaw that proves that the electrons can’t physically run into the nucleus and only jump orbit levels.
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Example of Bohr Model

Aluminum's atomic number is 13. It has 13 electrons and has three valence electrons in its outer shell. The first orbit is occupied with two electrons and the second orbit is occupied as well with ten electrons.