How are atomic numbers continuous in Periodic Table?


How come there are no gaps in the table? If there are 118 elements currently, and the next element to be discovered/created has an atomic number of 120, would there just be a gap at 119th position?

How come we managed to find/create every element without any gaps in the periodic table?

In: 104

The atomic numbers are just the quantity of protons which are obviously just positive integers (whole numbers, 1, 2,3, you can’t get 1.255 protons)

In fact your point is why the Periodic Table was so significant because before we arranged elements like this we *were* missing elements and didn’t know it! For example, the 1st periodic table didn’t have the noble gasses at all (we didn’t know they existed).

But some people sat down and say, Wait? Why are missing elements? And they went out and discovered them!

It’s totally possible we’ll find gaps as we discover new elements, but that doesn’t mean they don’t exist, we’ll leave a spot for them as we know they *must* exist, we just haven’t discovered them yet!

EDIT – as u/ComradeMicha has pointed out the largest elements are highly unstable and not found in nature, we can only create them for fractions of a moment within laboratory settings before they decay (break apart). There is a idea of something called “The Island of Stability” where we might discover (read: create in a lab) super heavy elements that *are* stable without decaying, but we haven’t discovered any yet.


There would just be a gap, and in some outdated periodic tables, there are gaps where we discovered elements out of order. We’ve discovered every element up to 118 because radioactive elements *generally* become less stable the heavier they are, so we’re more likely to discover them in order from lightest to heaviest.

The numbers in the periodic table are based on the number of protons that a particular atom has. Since protons are (for the sake of this ELI5) an indivisible unit, the periodic table can’t have any gaps – you can’t have half a proton in the nucleus of an atom.

We arrange them based on proton number because _that_ is what determines the nature of the atom itself. Atoms routinely gain or lose electrons, and while increased/decreased neutrons create isotopes that have _slightly_ different properties it is the proton that determines how the atom will behave.

This knowledge is what allowed us to construct the table, even when we had yet to discover particular atoms – we _knew_ they would be there because we can extrapolate the number of protons in the gap. This was the case for Technetium, which was only discovered in 1937, while the table itself dates back to 1869.

Each atom contains a nucleus, which consists of a number of protons and neutrons. These protons and neutrons attract and repel each other through a very complicated (and still not entirely understood) set of interactions involving three forces: the strong nuclear force, the weak nuclear force, and the electromagnetic force. It turns out that many different arrangements of protons and neutrons can form a stable nucleus, while others very quickly break apart (“decay”), and others last for a long time before decaying. The atomic number is simply the number of protons in the nucleus, and it turns out that for most atomic numbers there is at least one arrangement that is stable or that holds together for a reasonable amount of time before decaying.

Pretty much all of the stable isotopes can be found in nature somewhere (originally they were mostly created by fusion in stars, or in high-energy events such as supernovae) and many of the unstable ones are continuously created during natural decay processes. For example, there are no stable isotopes of uranium, but some of them decay *extremely* slowly, so there is still plenty of uranium around on earth even though it was created billions of years ago. The slow decay of uranium constantly produces various other isotopes, including for example isotopes of radon, none of which are long-lasting. But because it’s being constantly produced, radon gas can build up in caves and basements and cause health problems.

The remaining isotopes, mostly those with very high atomic numbers, have had to be created and detected in labs. The ones with the highest atomic numbers tend to be extremely unstable, so are very difficult to detect before they decay. In principle there might be an element whose isotopes are *so* unstable that it just isn’t feasible to detect them, so there might be a permanent gap, but that hasn’t happened yet.