Due to how vast the universe is, is it possible to find an element that is not on the periodic table? originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better understand the world.
The periodic table is just a list of elements: 1, 2, 3, 4, 5…. The number of the element was called the “atomic number” and once upon a time, it was just a number.
You can also order elements using other properties (particular chemical properties) so that the list of elements curves around in space, and things line up in a second or even a third dimension. It’s still a periodic table. It might not be the one you’re used to, but the one you’re used to is not like the one Mendeleev created anyway.
Once upon a time, the places of elements on the table were somewhat magical, because the number order wasn’t completely obvious, or physical. Mendeleev put them to begin with by weight, but then he found that he had to reverse a few element places (cobalt reversed with nickel, and tellurium with iodine, for example) to get the chemical properties to line up. So it was all kind of voodoo.
Then along came Rutherford, Bohr, and Moseley, in the years 1911–1914, and scientists found that the place of an element on the periodic table (atomic number) was not just a voodoo hack-up, like putting cards down in Solitaire. Instead, atomic number was a physical property — the number of positive charges (known to be “protons” after 1920) in an atom’s nucleus. As such, it could be measured in the laboratory (and when it was cobalt actually did come before lighter nickel, so it worked).
The list of elements was now a matter of “how many protons?” and it wasn’t something that could have gaps or holes ever again, once filled in, unless somebody discovered a way for an element to have a fraction of a proton or fractional charge in the nucleus. And so far, nobody has, though we think they exist. Even more importantly, such an element would blow itself to kingdom-come without an exact fractional charge analogue in the electrons surrounding the atom — and electrons appear far more stuctureless objects than do protons.
Note that the list of elements has no end. You can extend it as much as you like, and if there’s a gap of very unstable nuclides, followed by stable or nearly stable ones again, then our present table can accommodate. So again, the chance that the universe has a surprise for us, depends entirely on something wedged in between elements we know, which means somebody finding fractionally-charged protons and electrons, or something like them. That’s not likely.
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