By Richard Bleil
Science was built on failed experiments. We’re used to it. Some of the greatest advances in science are founded on failed experiments.
See, science is not knowledge. It’s hypothesis. What we teach in science are the models that best fit the current set of experimental data. Every good scientists lives with the knowledge that, tomorrow, some particularly bright young scientist will prove that atomic theory is wrong, but this certainly would not be a disappointment. After all, how exciting would it be to start over again?
In 1896, scientists were looking into the phenomena of a set of bizarre elements that just fell apart on their own. Called “radioisotopes”, the properties of the particles given off during this decay was being examined when, in 1897, the electron was characterized.
The properties of electrons were studied in vacuum tubes, with phosphorous screens on the opposite end of the electron emitter, and subject to a magnetic field in between. The beam of electrons were narrowed and focused, and the point where the electron beam would strike on the phosphorous screen would glow. If this sounds familiar to some of my older readers, this very same 19th century technology gave rise to televisions, with “cathode ray tubes, and televisions were invented in 1927. These “CRT’s” were in use in televisions and computer monitors for the next seventy years, and were not replaced until flat screen tvs became popular in the mid ’90’s.
Backtracking a bit, having a negatively charged particle implied the proton. After all, the world is electrically neutral, so in 1920 the existence of a positively charged particle, the proton, completed the expected subatomic particle discoveries. These particles were investigated with the same kind of phosphorous apparatus as electrons.
Imagine the surprise when, in 1932, the neutron was discovered. Originally called the “x-ray” (after all, “x” has been the letter of choice for the unknown since algebra), these strange particles were not influenced by magnetic fields at all, meaning they have no charge at all. In a sense, the discovery of the neutron is one of these “failed” experiments, but the failed experiment that I wish to discuss is Rutherford’s.
Before we discuss Rutherford, however, I would like to take a moment to acknowledge the more recently discovered sub-subatomic particles for my physics fanatical readers (quarks, leptons, etc.). As a chemist, I’m more interested in protons, neutrons and electrons, but these particles are what the protons, neutrons and electrons are made of, and they are seriously cool. But, on with the story.
Backtracking the the discovery of the electron, it was hypothesized that protons must also exist. These are anticipated to be the only subatomic particles, but, knowing of their existence is a far cry of knowing how they are arranged. The reigning hypothesis of the time was the “plumb pudding” model of atoms. Scientists knew the approximate volume of atoms since 1820 when Avogadro’s number was determined. If you take the volume of a sample, and divide that volume by the number of atoms, you get the approximate volume of an atom. Pretty straightforward. Subatomic particles, on the other hand, were discovered to be far smaller than atoms, so the “plumb pudding” model suggested that the (yet to be discovered) protons made up the majority of the volume, like pudding, in which the electrons were basically embedded like plumbs (which is a category that included “raisins”) in the pudding.
In one of the most important failed experiments in the history of chemistry, in 1911, Rutherford shot a beam of electrons through a very thin gold foil. This was a pretty standard experiment; he expected the beam to pass through, and create one bright spot on the phosphorous screen, but, he did something a little bit different. See, he wrapped the phosphorous screen all the way around the gold foil, three hundred sixty degrees. What he did not expect were glowing spots, some coming almost straight back from the gold foil target. If the plumb pudding model was correct, this would have been impossible. He made one of my favorite quotes in science when he exclaimed, “it was like shooting a cannon ball at a piece of tissue paper, and having the cannon ball bounce straight back towards me!”
The experiment failed. There simply had to be something in atoms that were dense enough to cause the reflection of the beam of electrons. The plumb pudding model failed, and he proposed a model of an atom with a dense center, a “nucleus”. It was only a couple of years later, in 1913, when Neils Bohr proposed his model that would be the foundation of the model picture of the atom with a center containing most subatomic particles (the anticipated proton and unexpected neutrons) would reside, with electrons in orbit around the nucleus.
I can’t help but think about the myriad of failed experiments in my life. My failed marriage (and plethora of failed relationships), my failed career paths, and so much more. Heck, even my failed dinner “creations”, but like my failed suppers, failure is an opportunity to learn. I think of the big failures in my life, and the lessons that I have learned. In one of my greatest failures, I tried opening my own lab. I’ve discovered that I lack the cutthroat attitude to run my own business. For example, we offered water testing as a service so people could find out if their water really needed to be filtered or not as a means of saving money, but refused to use “scare tactics” to test their water in an effort to sell such units. The relationships I have been in has shown me what I do not want in a relationship.
We all have our failures. The question becomes, will we use these failures to question what we believe we know so we can continue to grow, or let them define us?