Question

define atomic number and mass number the atomic number mass number of isotopes of Uranium are 92 and 235 respectively calculate the number of protons and neutrons in the nucleus of atom

Answer 1

ATOMIC number
The number of protons in the nucleus of an atom determines an element's atomic number. In other words, each element has a unique number that identifies how many protons are in one atom of that element. For example, all hydrogen atoms, and only hydrogen atoms, contain one proton and have an atomic number of 1.

ATOMIC MASS
Atomic mass number is the total no of protons and neutrons within the nucleus of an atom and it is symbolically represented as ‘A’ . for e.g. atomic mass number of hydrogen is 1 but we also have its isotopes i.e. deuterium and tritium whose atomic mass number is 2 and 3 respectively.

ATOMIC NUMBER OF U92 is 92 and mass number is 238


CALCULATE PROTON AND NEUTRONS IN NUCLEUS OF ATOM
Protons and neutrons (collectively called nucleons) are found in nuclei. On Earth, they are found in complex nuclei, e.g. Carbon with six protons and six neutrons. These nuclei were created in previous generations of stars — the Sun is likely the third generation of stars (confusingly called a Population 1 star) and the heavier elements from the debris cloud that formed the Sun is what became planets.

Only about 5% of the a galaxy’s mass is in stars, with the rest in gas clouds and other non-collapsed structures. This gas is primarily atomic or molecular hydrogren meaning that most nucleons in the Universe are isolated protons. All in, about 70% of the nucleons in the Universe are in hydrogen.

Isolated neutrons decay in a few minutes to a proton, electron and antineutrino, so they are not cosmologically stable. The either need to find protons (or other nuclei) in a few minutes or they decay. Most neutrons in the Universe are found in helium which is a composed of two protons and two neutrons. This was formed in the first minutes after the Big Bang during the era of Big Bang Nucleosynthesis. Because most neutrons don’t end up finding protons, there ends up being about 7 times as many protons as neutrons in the Universe.

Another place where we find protons is in cosmic rays, which are energetic particles raining down on us from elsewhere in the cosmos.

Isolated neutrons can be found around fission reactors when they escape or are directed out. They act a bit like uncontrollable marbles that bounce around hard surfaces until they get absorbed by nuclei or decay.