Wikipedia:Reference desk/Archives/Science/2022 January 23

= January 23 =

Exceptional configurations
I was puzzled by the fact that chromium and copper have five and ten electrons in 3d orbitals rather than four and nine. Now I have come to know from Dr. Wayne Breslyn's video that half-filled or completely filled d orbitals are more stable than those with one electron less. However, I found a few more exceptions in 4d orbitals, i.e., niobium, ruthenium, rhodium, and palladium, which are neither half-filled nor completely filled. What may be the explanation for the exceptional electronic configuration? Huzaifa abedeen (talk) 06:32, 23 January 2022 (UTC)
 * Check out the article on Aufbau principle. The "Exceptions" headings are particularly relevant.  Search the web for Madelung rule exceptions.  The neat math rules for calculating atomic shells do not work in all cases in the real world.  The math is an approximation that does not always match real world experiments.  If you can find the quantum (and beyond that) physics answer, please do write an article here about it.  Perhaps even collect your Nobel Price when you do that.  85.76.87.150 (talk) 15:57, 23 January 2022 (UTC)
 * Atomic orbital and electron configuration also have some useful information. As they discuss, when you start getting to large atoms with complex orbitals, the energies of different subshells can be very close or overlap. Nature always tries to fill the lowest-energy subshells first. There are also complicated effects that can come into play from electron-electron interactions, with electrons of different orbitals repelling each other (due to their negative electric charge) or one orbital "screening" the positive charge of the nucleus from another. --47.155.96.47 (talk) 05:04, 25 January 2022 (UTC)
 * "Nature always tries to fill the lowest-energy subshells first" as the whole statement, with then a bunch of exceptions and such, leads to my students thinking Nature is mostly exceptions. Instead, "Nature always tries to reach the lowest overall energy configuration." Then there are just a set of details what causes higher vs lower energy. DMacks (talk) 05:34, 26 January 2022 (UTC)

How different type of species were discovered before 1970s?
Omicron virus discovered through Genome Sequencing method used not before 1970s. How different type of species were discovered before 1970s? Rizosome (talk) 06:41, 23 January 2022 (UTC)
 * Please note that the Omicron variant is not considered a species of its own, but one of the variants of the SARS-CoV-2 species. Our article Virus classification explains how viruses are classified as species, most of which does not depend on genome sequencing but can be done by inspecting electron microscope images (for the phenotypic characteristics) and observing its macroscopic effects (host organisms and disease symptoms). --Lambiam 12:47, 23 January 2022 (UTC)
 * As the virus classification article states, the classification of viruses can be inconsistent and is very much an unsettled question. This is on top of the more general uncertainty of the species concept. People like nice, neat classifications with exact places to put everything and consistent rules for doing so. Nature is a LOT messier. --User:Khajidha (talk) (contributions) 16:07, 23 January 2022 (UTC)
 * Messy as it may be, such classifications may have a practical usefulness, from conservation efforts for vulnerable species to developing effective medication for diseases with identifiable pathogens. --Lambiam 21:58, 23 January 2022 (UTC)
 * "Conservation efforts for vulnerable species"? I think the vulnerable species is man, not some virus! Martin of Sheffield (talk) 22:02, 23 January 2022 (UTC)
 * I reacted to a contribution referring to "the more general uncertainty of the species concept" – which even applies to proposed extinct (sub?)species in the genus Homo. --Lambiam 13:39, 24 January 2022 (UTC)
 * Along with the ongoing question about whether viruses are really "alive" or not. --←Baseball Bugs What's up, Doc? carrots→ 16:51, 23 January 2022 (UTC)

This line solved my doubt: Our article Virus classification explains how viruses are classified as species, most of which does not depend on genome sequencing but can be done by inspecting electron microscope images (for the phenotypic characteristics) and observing its macroscopic effects (host organisms and disease symptoms). Rizosome (talk) 07:04, 24 January 2022 (UTC)

Adhesive for use on skin
I mean the stuff on band-aids and adhesive tape, not surgical adhesive. Any idea what it is that they use, and where to get it? Somehow separating it from adhesive tape might be a possibility if there's no other way. Application is strapless n95 masks, which stay on with adhesive (look up "Readimask"). They apparently work pretty well on first use, but aren't easily re-usable because the adhesive loses its stickiness. Thus, the is to find a way to add more. The masks seem like a nice idea but they are on the expensive side. 2602:24A:DE47:B8E0:1B43:29FD:A863:33CA (talk) 08:11, 23 January 2022 (UTC)
 * Our article Adhesive bandage has this to say: "The adhesive is commonly an acrylate, including methacrylates and epoxy diacrylates (which are also known as vinyl resins).[2]" --Lambiam 12:53, 23 January 2022 (UTC)
 * Thanks, I should have looked there. I also found a less expensive source of strapless masks. 2602:24A:DE47:B8E0:1B43:29FD:A863:33CA (talk) 02:26, 24 January 2022 (UTC)