Back to Basics….
As some of you may have noticed, there have been more than a few research papers and write-ups mentioned or linked here on the Café. Some of the concepts that are discussed in them may be outside of the casual readers realm of knowledge… either by never hearing of it, or by having forgotten much of it. A lot of it is easy to forget if you don’t use or think about it often.
To start, a long time ago (about 2500 years) in a place far far away (unless you are in Greece near 37° 58′ 0″ N, 23° 43′ 0″ E) it came upon a guy, that if you keep cutting something in half, then cut those parts in half, eventually you will get to the point where you can’t cut it in half anymore. This indivisible smallest part of something was the birth of the idea of an atom. The idea may not be fully greek, since the idea does show up in ancient Indian texts also. But in more modern times the concept has held true with a slight modification. (layman’s version) An atom is the smallest division of something that still holds characteristics of the parent material. In this case elements. If you take an atom of any element, when you tear it apart, what you have left does not in any way behave like the parent atom did. (except maybe for the single proton that you find in a Hydrogen atom.
Imagesource: Wikimedia Commons
Atoms are made up of subatomic particles. Protons with a positive charge. Neutrons with no charge (neutral) and electrons with a negative charge. These particles reside in specific areas of the atom… the Nucleus, and the Electron shells (cloud). In the Bohr model of the atom, (thought up by famous Dane Niels Bohr) the electrons orbit the nucleus in shells. From Wikipedia “The 1st shell can hold up to two electrons, the 2nd shell can hold up to eight electrons, the 3rd shell can hold up to 18, and 4th shell can hold up to 32 and so on.”
Neutrally charged atoms have an equal number of electrons as protons. Add or subtract electrons and you get an ion of that atom. (negative ion – an excess of electrons). But it still remains and acts like that element. It’s identity is principally determined by the number of protons. The number of neutrons is usually quite close to the number of protons, but when you deviate from the normal you get “isotopes” of the element. Isotopes can either be stable or unstable. Unstable ones tend to decay by releasing /some sort of radiation. Uranium 238 (the most common isotope of uranium) is inherently radioactive in it’s natural state. U238 decays through the Alpha process and releases 4.267 MeV of energy in the form of two protons and two neutrons (an alpha particle). The end product is Thorium 234. By itself, U238 is not fissile, meaning that it can not sustain a chain reaction. But if neutrons passing by are slowed down, they can be captured and make plutonium-239 which is fissile. The slowing down of fast moving neutrons is what made the Oklo natural reactor function. Most elements have isotopes. In general the ratios of the different isotope concentrations are somewhat fixed, with only processes like neutron capture or radioactive decay being able to change that. However, some biological processes can alter these ratios. If you are playing soccer, and you encounter a soccer ball that has a mass of 7.3 kg, you are not going to want to kick it around, let alone bounce it off your head or chest. Usually, soccer balls are around .4 to .5 kg.
Fair warning: This is an absolutely HORRIBLE thing to do to another person. DO NOT try to replicate this “stunt.” The guy filming the video is lucky to have only lost a friend. It is irresponsible and (if real) probably put the victim in the hospital to have his foot looked at, plus, potentially costing him his job.
Likewise, heavier isotopes may be more difficult for a cell or organism to use, so they would preferentially use that material that they were best suited for. This isotopic signature (the ratio) is used quite a bit to puzzle out how material got to where it is at.
In my sulfate digging, I ran across more than one researcher who was looking for an isotopic signature in the sulfate try and determine it’s source. From what I have read, they were unsuccessful. But It did set me to thinking about the sulfate signal in the ice-cores. Sulfate that settles onto the ice does not have to have come from the stratosphere. It should really be no different in appearance from tropospheric originated sulfate. So, just because you see a monster SO4 spike in the Vostok or GISP core, that doesn’t mean that it was from the stratosphere.
Other fun things about the atom. The Shells (orbitals) that the electrons orbit in, can be manipulated by the addition or release of energy. Light can excite an electron to jump to a higher energy orbital. When it falls back it will release an amount of enegy. You probably witness this on a day to day basis in fluorescent light fixtures. Mercury vapor, excited by the electric current passing through it, releases ultraviolet light. The white light that you see from the bulb is due to the phosphor coating on the inside of the glass envelope, which goes through a similar process, though it’s electrons are responding to the UV light and releasing visible light when the electrons drop back down to a lower energy orbit. Technically, those bulbs are off 50 to 60 times a second (depending on your power grid) as the AC current reverses. Lasers operate based on achieving and maintaining a population inversion of the number of excited atoms to non-exited atoms. Once they cascade, the energy is released in sync with all the other excited atoms.
Sorry for the diversion…. But stepping a bit further into the realm of “funky things that you can do with atoms,” as noted earlier, atoms can (and do) absorb photons… well, specifically, the energy from the photons. When they do, they remove (attenuate) light at that spectral frequency. I mentioned in a previous post that carbonyl sulfide can be dissociated by light in the UV-C range (≈200 nm) This would show up as an absorption line in light passing through the gas. A similar thing happens at the atomic level, but it’s from electrons being shoved into higher energy orbitals. This was discovered as emission and absorption lines, the Lyman and Balmer series (and others) of spectral lines. This was a really tidy reinforcement of the Bohr model of the atom. This characteristic has been used to analyze gases from the magma entry points into the sea in Hawaii to determine what sort of stuff happens when sea-water interacts with magma. (I’ve mentioned some of the results when yammering about HCL as a byproduct of this action.
Well, I hope this helps to either jog your memory, or at least help with some of the stuff in the papers that we occasionally link to.
Caveat: This is mostly first year physics stuff. I reserve the right to be outright wrong. But if I am, a polite person would provide the needed corrections in addition to slapping me silly.
“Any sufficiently advanced technology is indistinguishable from magic.” Author C Clarke