Nucleosynthesis isotopes

Free neutrons are unstable with a half-life of about ten minutes The abundance ratio was about seven protons for every neutron. Before one neutron half-life passed nearly every neutron had paired up with a proton, and nearly every one of these pairs had paired up to form helium. By the time the universe was three minutes old the process had basically stopped and the relative abundances of the elements was fixed at ratios that didn't change for a very long time:

Nucleosynthesis isotopes

The Universe is now 1 minute old, and all the anti-matter has been destroyed by annihilation with matter. The leftover matter is in the form of electrons, protons and neutrons. As the temperature continues to drop, protons and neutrons can undergo fusion to form heavier atomic nuclei.

This process is called nucleosynthesis. Its harder and harder to make nuclei with higher masses.


So the most common substance in the Universe is hydrogen one protonfollowed by helium, lithium, beryllium and boron Nucleosynthesis isotopes first elements on the periodic table.

Isotopes are formed, such as deuterium and tritium, but these elements are unstable and decay into free protons and neutrons. Note that this above diagram refers to the density parameter,of baryons, which is close to 0.

However, much of the Universe is in the form of dark matter, which brings the value of M Nucleosynthesis isotopes 0. A key point is that the ratio of hydrogen to helium is extremely sensitive to the density of matter in the Universe the parameter that determines if the Universe is open, flat or closed.

The higher the density, the more helium produced during the nucleosynthesis era. There are over naturally occurring elements in the Universe and classification makes up the periodic table. The very lightest elements are made in the early Universe.

The elements between boron and iron atomic number 26 are made in the cores of stars by thermonuclear fusion, the power source for all stars. The fusion process produces energy, which keeps the temperature of a stellar core high to keep the reaction rates high.

The fusing of new elements is balanced by the destruction of nuclei by high energy gamma-rays. Gamma-rays in a stellar core are capable of disrupting nuclei, emitting free protons and neutrons. If the reaction rates are high, then a net flux of energy is produced. Fusion of elements with atomic numbers the number of protons greater than 26 uses up more energy than is produced by the reaction.

Thus, elements heavier than iron cannot be fuel sources in stars. And, likewise, elements heavier than iron are not produced in stars, so what is their origin?. The construction of elements heavier than Fe iron involves nucleosynthesis by neutron capture.

A nuclei can capture or fuse with a neutron because the neutron is electrically neutral and, therefore, not repulsed like the proton. In everyday life, free neutrons are rare because they have short half-life's before they radioactively decay.

Each neutron capture produces an isotopesome are stable, some are unstable.

Nucleosynthesis isotopes

Unstable isotopes will decay by emitting a positron and a neutrino to make a new element. Neutron capture can happen by two methods, the s and r-processes, where s and r stand for slow and rapid.

The s-process happens in the inert carbon core of a star, the slow capture of neutrons. The s-process works as long as the decay time for unstable isotopes is longer than the capture time. Up to the element bismuth atomic number 83the s-process works, but above this point the more massive nuclei that can be built from bismuth are unstable.

The second process, the r-process, is what is used to produce very heavy, neutron rich nuclei. Here the capture of neutrons happens in such a dense environment that the unstable isotopes do not have time to decay.

The high density of neutrons needed is only found during a supernova explosion and, thus, all the heavy elements in the Universe radium, uranium and plutonium are produced this way. The supernova explosion also has the side benefit of propelling the new created elements into space to seed molecular clouds which will form new stars and solar systems.

Constant impacts by photons knock electrons off of atoms which is called ionization. Lower temperatures mean photons with less energy and fewer collisions. Thus, atoms become stable at about 15 minutes after the Big Bang. These atoms are now free to bond together to form simple compounds, molecules, etc.

Nucleosynthesis isotopes

And these are the building blocks for galaxies and stars. Even after the annihilation of anti-matter and the formation of protons, neutrons and electrons, the Universe is still a violent and extremely active environment. Radiation, in the form of photons, and matter, in the form of protons, neutrons and electron, can interact by the process of scattering.

Photons bounce off of elementary particles, much like billiard balls. The energy of the photons is transfered to the matter particles. The distance a photon can travel before hitting a matter particle is called the mean free path.Isotopes of nihonium.

Nihonium (Nh) is a synthetic element. Being synthetic, a standard atomic weight cannot be given and like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was Nh as a decay product of Mc in Primordial Nucleosynthesis and the abundances of the light elements.

In the time period between about seconds and 30 minutes after the Big Bang, but mostly with the first three minutes, the temperature and density of the universe were appropriate for the efficient synthesis of the light elements. Primordial nucleosynthesis supposedly produced six isotopes: the two isotopes of hydrogen (1 H and 2 H), the two isotopes of helium (3 He and 4 He) and the two isotopes of lithium (6 Li and 7 Li).

The exact amount of lithium produced is difficult to determine. Big Bang Nucleosynthesis The Universe's light-element abundance is another important criterion by which the Big Bang hypothesis is verified.

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It is now known that the elements observed in the Universe were created in either of two ways. Livermorium (Lv) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes.

The first isotope to be synthesized was Lv in There are four known radioisotopes from Lv to Lv, as well as a few suggestive indications of a possible heavier isotope Lv. 33 rows · big bang nucleosynthesis. By the first millisecond, the universe had cooled .

Big Bang Nucleosynthesis