Elements

[Goldfinger]

In this vast universe, have we discovered all the elements? Or could there still elements we're not aware of? Just food for thought.

[vlaiv]

 

[Lariliss]

1. The periodic elements table starts with hydrogen: one proton and one electron. Then there is helium: two protons and two electrons. Then it goes with bigger and bigger atoms

It is not defined how much longer the table can be extended by the creation of new elements. Some suspect there is no limit.

2. Many elements were created in the lab, and lots of them are unstable before decay (e. g. into plutonium, lead).

So, they are created on Earth, using a particle accelerator, rather than found in nature or the universe.

It is possible that in some state or place in the universe that is not observed those elements from the periodic table or new (?) could be found.

[Zermelo]

We have discovered all the elements that exist in nature and are stable to 'normal' modes of decay (if the proton ever decays, then no elements are stable in perpetuity).
For decades, various isotopes of unstable elements have been synthesized, with half-lives ranging from the tiniest fraction of a second up to millions of years.
The general pattern is that, as the atomic number of the synthesized element increases, the faster it decays. But there are exceptions, and theoretically there might be "islands of stability" - isotopes that have "magic" numbers of protons and neutrons and are particularly long-lived. This holds out a small hope that we could synthesize very heavy elements that might be stable, or at least have a long half-life. But there is no consensus on where these "islands" might lie, and another problem is that such nuclei would require more neutrons to be stable than are available in the source materials that might be used to produce them.

Edited August 30, 2021 by Zermelo

[City9Town0]

I thought that the 'half-life' of a proton was of the order of 10^32 years so 'unstable' in Universe terms but pretty stable in terms of my weekly calendar...

Maybe we are close to the complete set of isotopes...

[Felias]

2 minutes ago, Zermelo said:

 But there are exceptions, and theoretically there might be "islands of stability" - isotopes that have numbers of protons and neutrons that are particularly long-lived. This holds out a small hope that we could synthesize very heavy elements that might be stable, or at least have a long half-life. But there is no consensus on where these "islands" might lie, and another problem is that such nuclei would require more neutrons to be stable than are available in the source materials that might be used to produce them.

You can always collect them from the heart of a supernova... 😁

[Lariliss]

The core of a neutron star contains some protons (and electrons) as well as neutrons as superfluid degenerate matter.

Wikipedia:

Current models indicate that matter at the surface of a neutron star is composed of ordinary atomic nuclei crushed into a solid lattice with a sea of electrons flowing through the gaps between them. It is possible that the nuclei at the surface are iron, due to iron's high binding energy per nucleon. It is also possible that heavy elements, such as iron, simply sink beneath the surface, leaving only light nuclei like helium and hydrogen.

Proceeding inward [..] The expected hierarchy of phases of nuclear matter in the inner crust has been characterized as "nuclear pasta", with fewer voids and larger structures towards higher pressures. The composition of the superdense matter in the core remains uncertain.

Is it possible, that in between the uncertainties of a neutron stars some elements produced, or this is just a collapse to a mass of free particles?

[Zermelo]

39 minutes ago, Lariliss said:

The core of a neutron star contains some protons (and electrons) as well as neutrons as superfluid degenerate matter.

Wikipedia:

Current models indicate that matter at the surface of a neutron star is composed of ordinary atomic nuclei crushed into a solid lattice with a sea of electrons flowing through the gaps between them. It is possible that the nuclei at the surface are iron, due to iron's high binding energy per nucleon. It is also possible that heavy elements, such as iron, simply sink beneath the surface, leaving only light nuclei like helium and hydrogen.

Proceeding inward [..] The expected hierarchy of phases of nuclear matter in the inner crust has been characterized as "nuclear pasta", with fewer voids and larger structures towards higher pressures. The composition of the superdense matter in the core remains uncertain.

Is it possible, that in between the uncertainties of a neutron stars some elements produced, or this is just a collapse to a mass of free particles?

I've heard neutron stars likened to "one giant nucleus", but the predictions in these models are very interesting. A verification by observation would be amazing. LIGO has apparently detected the signatures of heavy elements in the gravitational waves from collisions.

19 hours ago, City9Town0 said:

Maybe we are close to the complete set of isotopes...

This is another interesting read.

[Gfamily]

On 31/08/2021 at 18:01, Zermelo said:

. A verification by observation would be amazing. LIGO has apparently detected the signatures of heavy elements in the gravitational waves from collisions.

Hmmm, are your sure? 

I thought there was a detection of spectra from heavy elements in the visual wavelength observations made for  the Neutron Star - Neutron Star merger that was correlated to a detection by LIGO, rather than it being anything that was detectable in the Gravitational Wave signal.

 

Edited September 3, 2021 by Gfamily

[Zermelo]

14 hours ago, Gfamily said:

Hmmm, are your sure? 

I thought there was a detection of spectra from heavy elements in the visual wavelength observations made for  the Neutron Star - Neutron Star merger that was correlated to a detection by LIGO, rather than it being anything that was detectable in the Gravitational Wave signal.

 

Yes, that would make more sense, I possibly read a condensed account that merged the two observations. I was surprised that the wave properties could be used to infer the masses of the colliding objects, never mind the production of heavy elements. And I think I read more recently that they've revised downwards the quantity of heavy elements originating in neutron star collisions, versus other mechanisms.