We went into a lot more detail regarding the atomic theory of Niels Bohr. It was a very BOHRing (not BORing) class today!
NIELS BOHR
Niels Bohr was one of the most influential scientists of the 20th century. He was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, and received the Nobel Prize for Physics in 1922. 
EVIDENCE
Mr. Bohr expanded on Rutherford's theory (that the atom consisted of a positively charged nucleus with negatively charged electrons orbiting around it). Rutherford's model was inherently unstable (protons and electrons should attract each other)!
Bohr noticed that when white light was passed through a prism, the visible spectrum of light was obtained:
In contrast to this, he also saw that a line spectrum (which contains distinct lines of a particular color) was obtained when light of a particular color (like from the hydrogen discharge tube) was passed through a prism.
Bohr based his model on the energy (light) emitted by different atoms. Note that matter emits light when it is heated:
We can make objects and gasses glow by heating them up in a flame, or by passing electricity through them. The spectroscope spreads out the colors of the light, and we can identify the elements by the bright lines we see in the spectroscope. Black body radiation is the thermal radiation that would be emitted by a blackbody (that is, an ideal object that would absorb all of the radiation incident on it without reflecting any radiation). The distribution of energy in such radiation depends solely on the temperature of the source.
Light travels as photons. A photon is a quantum of visible light or other form of electromagnetic radiation demonstrating both particle and wave properties. It has neither mass nor electric charge but possesses energy and momentum. The energy photons carry depends on their wavelength.
Each element gives off a specific colour of light (emission spectra). It is unique to each element. When hydrogen is excited in a gas discharge tube, it emits its well-known line spectrum:
This allowed Bohr to put forward his model of the atom, which is still used, with modifications, to describe the atom today. To explain this emission spectra, he suggested that electrons occupy shells or orbitals.
BOHR'S THEORY
Bohr proposed that electrons only occupy certain orbits or shells in an atom. Also, each orbit represents a definite energy for the electrons in it. When they absorb energy, they move to a higher orbital. As they fall from a higher orbital to a lower one, they release energy as a photon of light.
An excellent website to help answer further inquiries: http://www.colorado.edu/physics/2000/quantumzone/bohr.html
A video on Bohr's theory:
Tune in next time when we look at his model in depth and learn how to write bohr diagrams!
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