How many chemical elements are there

Have all the chemical elements been discovered or could there be more?

From hydrogen to uranium: the chemical elements with ordinal numbers 1 to 92

Possibly - but unlikely. Of course, science can only make statements about things it can investigate - but it cannot prove that certain things do not exist in the universe.

What it can say: On the basis of the previously known laws of nature, there should be no as yet unknown elements in the universe. This is because the chemical elements - as they are in the known periodic table - follow an internal system. What distinguishes them from one another is primarily the number of protons - that is, the positively charged particles in the atomic nucleus. The elements are practically numbered: hydrogen has one proton, helium has two, lithium has three. Then it goes on to beryllium - four - and boron - five. Then come the carbon, nitrogen and oxygen that are so important to us with the ordinal numbers 6, 7 and 8.

This list goes on and ends - at least for the natural elements - at 92; that's how many protons uranium has. Uranium is the heaviest naturally occurring element, at least on earth.

But atoms are not only made of protons, but also of electrons and neutrons. Why are elements only defined in terms of the number of protons?

On the one hand, the number of protons also directly determines the number of electrons. The properties of an atom in turn depend on these: whether and how it connects with other atoms and molecules, how it reacts to radiation, what it looks like, how it behaves electrically, whether it conducts electricity or not. It is all these properties that give an element its typical “character” in the first place. And these properties depend on the number of protons.

But have you always discovered elements that are even heavier than uranium?

There are still a few elements that are heavier - but they have always been artificially created, including the well-known plutonium, which is an unwelcome waste product in nuclear power plants. It has the atomic number 94 - so it has two more protons than uranium.

The periodic table even knows other elements up to atomic number 118 - the "Ununoctium". But all of these elements, which are heavier than plutonium, are extremely unstable. They can only be produced artificially and are highly radioactive - i.e. they disintegrate in a fraction of a second. This would also apply in other parts of the universe - provided, of course, that the same laws of nature prevail there.

And how do we know?

That is the remaining unknown: We can assume that the same laws apply in the entire universe and that the natural constants have the same value - but we cannot be absolutely sure. We can only say: The laws known to us ensure that matter is made up of the atoms known to us. And we know all the atoms that can potentially exist according to these laws.

The text and audio of this post are licensed under the CC BY-NC-ND 4.0 Creative Commons license.