Niels Bohr is known to many as the brilliant Nobel Prize winning physicist who helped the world better understand quantum mechanics and colloborated on the famous Manhattan Project; however, Bohr’s contribution influenced more than physics. His work was also crucial to physics’ sister science of chemistry.
From Philosophy to Physics
Niels Bohr was born in 1885 at a time when there were revolutionary advances in scientific thought. Bohr’s father was a Professor of Physiology and was famous for explaining hemoglobin PH and absorption (called the Bohr effect). Raised in a family of academics, he was afforded the ability to experiment and question.
In 1905, barely 20years old, Bohr, prompted by a gold medal competition sponsored by the Royal Danish Academy of Sciences and Letters, conducted a series of experiments to examine the properties of cohesion of liquid molecules on surfaces (surface tension.) Bohr won the prize and switched his studies from philosophy to physics.
Early Work
By 1911, Bohr completed his doctorate at University of Copenhagen and became a post-doctoral student at Cambridge. While at Cambridge, Bohr first conducted experiments under Nobel Laurette and discoverer of the electron and of isotopes, Sir Joseph John Thomson. Later Bohr would study under Ernest Rutherford, Nobel Prize winning chemist and discoverer of the proton.
Through the influence of these trailblazers, Bohr began considering the structure of atoms. The electron, proton and nucleus were known. Neutrons had not been confirmed at the time. On the basis of Rutherford’s theories, Bohr published his theory on the model of atomic structure in 1913. It was Bohr who theorized that electrons travel in orbits around the nucleus. Visualize an atomic sized solar system. This was different from prior ideas about the structure of atoms. Bohr also theorized that electrons could drop from higher to lower orbits and emit energy in the form of photons. Bohr’s model considered the teaching of his mentors and the new age ideas of Einstein and Max Planck.
Bohr’s Atomic Model considered the following:
1. that electrons revolve in stable orbits and that those orbits they have a specific angular momentum which can be quantified by speed, orbit and mass;
2. that, while in their stable orbits, electrons do not radiate energy;
3. that when energy is introduced, an electron leaves its orbit, even if momentarily, and emits energy. This temporary state is called the excited state. And, the energy emitted is in the form of electromagnetic waves.
Several factors came from this theory including Bohr’s frequency and quantification conditions. The model also explained Ryberg formula for atomic hydrogen spectral emissions.
For this pioneering work, Bohr earned the 1922 Nobel Prize in Physics. Bohr’s contribution was two-fold because not only did his work transform views on atomic structure. It also let the world better understand that atoms radiate energy.
Bohr’s work clarified the model of the atom and allowed scientists to figure out a more accurate model for hydrogen. It also explained energy emissions during chemical reactions and the rationale behind radiation. His work continued in atomic theory where he and physicist John A. Wheeler devised the theory of atomic fission.
Chemistry and Physics are linked. While both deal with the nature of matter and energy, chemistry deals more with the interactions of atoms and their reactions in chemical processes. Niels Bohr’s work made it easier to understand how atoms chemically react and for his pioneering work, he should also be considered an icon of chemistry.”
For more information about the life and works of Niels Bohr, the library and local bookstores have a number of great books. The web also has some great resources, check out the following websites:
http://nobelprize.org/nobel_prizes/physics/laureates/1922/bohr-bio.html
http://www.pbs.org/wgbh/aso/databank/entries/bpbohr.html
