[hallenrm]

Element is one of the fundamental concepts of chemistry.

According to wikipedia:

As of 2005, there are 116 known elements: 93 occur naturally on earth (including technetium and plutonium), and 94 (including promethium) have been detected in the universe at large. The 23 elements not found on earth are derived artificially; technetium was the first purportedly non-naturally occurring element to be synthesized, in 1937, although trace amounts of technetium have since been found in nature. All artificially derived elements are radioactive with short half-lives, so if any atoms of these elements were present at the formation of Earth are extremely likely to have already decayed.

Now the question arises, is 116 the final number of elements that can be detected? Can the theoretical chemists can ever predict a number that tells how many elements can there be, from the present knowledge of all natural forces?

[Mercedes Benzene]

I thought I once heard an arguement that stated there could only be a certain number of chemical elements. I'm not exactly sure what the number was, or what the reason was, but I'll try to find it.
Obviously, at least on earth, it is extremely hard to produce anything beyond about 100-ish. Obviously these elements have been created, but in barely measurable amounts.
Perhaps in another galaxy somewhere, higher elements are created in some unknown process, but I think there is a maximum to what stars can naturally produce.

[ronthepon]

I'll just put post some concepts that can be found in my text book.

1- Maximum stability for low mass nuclei lies the the neutron-proton ratio being close to one.

2- For heavier nuclei, the ratio tends to be shifted to the neutron direction.

http://chimge.unil.ch/En/nuc/1nuc2.htm

Apparently because the strong forces between nucleons get 'overwhelmed' by the repulsion between protons, when there are too many protons.

The things get bad when the nuclei get too big, as the nuclear forces are rather short ranged.

Personally, I feel that building heavier and heavier elements will get harder, and they shall exist for lesser amounts of time. However, I doubt the assertion that there shall be a 'last element'.

I mean, suppose in a violent particle collision, un un septium (Element no. 117) did exist, but very momentarily, and we failed to detect it because it vanished in yoctoseconds... or simpy because we were not trying to find it.

But then, there is a chance that there is a maximum limit... the limit arising from quantum-ness of energy posessed.

[HydrogenBond]

As we build larger and larger atoms nuclear repulsion increases as ronthepon pointed out. There is also another limiting factor. Under the hot conditions needed to make biggest elements, the ionized electrons plus others are eventually pulled in, with the resulting exothermic EM output able to break the nuclear forces that bind the nucleus.

For example, if we totally ionzed oxygen and let all the electrons come back into the atom, the total energy output is not able to break the nucleus apart. For very large atoms, this same degree of ionization, giving off the same energy, has an easier time disrupting the stability of the nucleus since the larger nucelus is in a more hair-trigger situation due to nuclear repulsion. The net affect is the energy needed to make higher atoms beyond a limit, ionizes too many electrons such the electron recoil disrupts the nucleus that was gained.

[hallenrm]

Let us first take a fresh look at the concept element!

The concept of an element was introduced in the quest of analyzing matter around us. It was realized through tools of chemistry that many substances can be reduced to several other substances that cannot be broken up further using the tools of classical chemistry. Such substances that are elementary to all other chemical substances were called chemical elements.

The tools of modern chemistry after the advent of nuclear physics revealed that even elements can be reduced, into subatomic particles called electrons, protons and neutrons. Thus the old definition of chemical element gave way to a new definition, as a unique aggregate of subatomic particles. This definition prompted nuclear chemists to discover synthetic elements. These elements unlike the natural elements do not have a long life (sometimes not more than a nano second).

The new definition of an atom of an element leads to yet another adventure. Atomic aggregates emit characteristic electromagnetic radiations that can travel far. Scientists reasoned that certain sub-atomic particle aggregates can not be found on the Earth, because the conditions on the Earth are not conducive for their survival, They may as well be existing on remote stellar bodies. We can detect them through spectroscopic studies of radiations from such bodies. That explains the discovery of several other elements.

Before coming back to the original question, let us now ask a few more questions:

Are the subatomic particle aggregates, that are made up of electrons, protons and neutrons, the only kind of aggregates that can exist anywhere in the universe?

Are other types of aggregates possible? If yes can we call them atoms of elements.

Which means we need to widen the definition of chemical elements and their atoms, if we want a more meaningful search.

Any takers?

[mir]

Originally Posted by hallenrm

Let us first take a fresh look at the concept element!
Are the subatomic particle aggregates, that are made up of electrons, protons and neutrons, the only kind of aggregates that can exist anywhere in the universe?

Are other types of aggregates possible? If yes can we call them atoms of elements.

Which means we need to widen the definition of chemical elements and their atoms, if we want a more meaningful search.

Any takers?

Im not a nuclearchemist, but this is my opinion:

We dont know about the answers of any these questions. Its philosophy.
But what I can dare to imagine, is what we see here on earth is representable for all the known universe (we have spectroscopy in astronomy too). Except by the ratios between the elements (that is uniqe to Earth and the Sun - There is even slight differences in ratios between the asteroids and the Earth). If there is other charged aggregate-possibilities - then we should have already noticed them in at least

[hallenrm]

If there is other charged aggregate-possibilities - then we should have already noticed them in at least

Yes if we have had means to do so