Computational Chemistry Lab: The Bohr Atom

Objective

In this lab activity, you will be using the spreadsheet to calculate the energy levels, frequencies, and wavelengths of electrons in orbits. The question is: how can we observe transitions (movement) of electrons from an excited state to a ground state? We are also interested in knowing: which series can we see?

Background

In chemistry, we are interested in the movement of electrons in orbit around the nucleus of an atom. The electron normally occupies the level closest to the nucleus. In this level the energy of the electron is at its lowest; this state, with a principle quantum number (n) equal to 1, is commonly called the ground state.

Atoms can absorb energy through their electron structures in the form of energy packet (or "quanta") called a photon. When this energy packet is absorbed, the electron in orbit around the nucleus move to a higher (more distant) level. This level is called the excited state. Naturally, the electron cannot remain at this excited state for a very long time (it stays there for about 10-8 seconds, or for .00000001 seconds). When the electron "falls" back to the ground state level, energy is released. Depending on the wavelength of this fall, you might be able to see the energy released in the form of color (ie, a burst of light). Any energy with a wavelength between 380 and 750 nanometers (nm) will be visible to most people.

Your objective in this lab is to create a spreadsheet that will allow you to calculate the change in energy, the frequency, and the wavelength when an electron moves from an excited state to a ground state. You will be asked to use the full electromagnetic spectrum to predict which part of the spectrum appears for several different energy levels.

The equations you will need to model are as follows:

Electromagnetic Spectrum

Wavelength Range (nm)Radiation Produced
Less than 185X-rays
185-380Ultraviolet
380-450Violet
450-495Blue
495-550Green
550-570Yellow-Green
570-590Yellow
590-620Orange
620-750Red
750-1900Near Infrared
1900-2500Infrared
Above 2500Microwaves, radiowaves

Case Study Instructions

Hint: use the "fill" command to save yourself typing! Work smarter, not harder.

Sample Spreadsheet:


Historical note: transitions from n=7,6,5,4,...2 to 1 are known at the Lyman series. Other named series are:


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