02.09.10
Hadrons, Isotopes, Beta-Decay
In my last quarter of the General Chemistry sequence we started examining something called beta-decay. It presented the possibility of essentially changing one atom into another, say start with silicon and end up with phosphorus.
This has to do with the interplay of what makes up all atoms, like everyone learned in high school, we have protons(+) and neutrons(0) in the nucleus, and a bunch of electrons(-) swarming around them. The number of protons in an atom determines the identity of the atom and are balanced by the number of electrons swarming around the atom. The neutron has no charge, so this does very little in the atom other than determine how heavy it is.
You can add and subtract neutrons from the nucleus without changing the identity of the atom. When you do this you get what are called isotopes. Each atom has a stable number of these neutrons, and when you find isotopes that are not stable, they stabilize by undergoing beta decay.
My teacher described the process in which a neutron in an atom decays into a proton, and emits an electron. So we have silicon undergoing a beta decay, one of its neutrons falls apart and becomes a proton while emitting an electron resulting in the formation of the neighboring element on the periodic table, phosphorus. She then quickly added that a neutron is NOT an electron and proton combined, but a proton and electron could be combined to form a neutron in a process known as electron capture.
This is the type of statement that really ruins my day, sometimes my week. It really kept me up at night on more than one occasion. Why can a neutron become a proton and an electron? Why does it contain neither? The answer lies in the even smaller forms of matter known as quarks. Protons and neutrons are actually stable forms of quark configurations known as hadrons. These are held together by a force, which is called the strong force, and is the strongest force we know of. This force contains energy which is capable of containing some mass in the form of the famous equation E=MC^2. In this interaction between the quarks that make up these particles, rearrangements are allowed to happen to obtain stability, and in the process energy is released, sometimes in the form of harmful radiation, as is the case of radium, which led to the painful death of Marie Curie in 1934. Energy creates mass and mass can create lots and lots of energy.
Above is a pretty well known photograph of hadrons traveling in a gas, leaving trails behind them. The paths are studied to determine masses of the particles which cannot be seen directly.
