In heavy nuclei, the Coulomb energy of proton repulsion becomes very significant and this makes the nuclei unstable. It turns out that it is energetically more profitable for a nucleus to throw out a stable system of four particles, i.e., an alpha particle, than individual nucleons.
Why are small nuclei more stable than large nuclei?
Smaller nuclei are usually more stable because the strong force acts over most all of the particles . As the nuclei gets larger, the repulsion between protons is becomes greater than the strong force causing the nuclei break apart.
Why are smaller nuclei unstable?
They are referred to as “neutron rich”. Those that lie below the line of stability contain too many protons to be stable and are called “proton rich”. ... Too many neutrons or protons upset this balance disrupting the binding energy from the strong nuclear forces making the nucleus unstable.
Are smaller nuclei more stable?
A nucleus has less mass than the total mass of its constituent nucleons. ... Of the many nuclides that exist, only a small number are stable . Nuclides with even numbers of protons or neutrons, or those with magic numbers of nucleons, are especially likely to be stable.
Why some nuclei are unstable?
Why some elements are radioactive (unstable). When the atoms of an element have extra neutrons or protons it creates extra energy in the nucleus and causes the atom to become unbalanced or unstable . Whether radioactive elements can become stable and if so, how. The unstable nucleus of radioactive atoms emit radiation.
Why are large nuclei Z 83 typically unstable?
Atoms with very low atomic numbers have about the same number of neutrons and protons; as Z gets larger, however, stable nuclei will have more neutrons than protons. ... Nuclei with more than 83 protons are all unstable , and will eventually break up into smaller pieces; this is known as radioactivity.
Why are all elements above 82 unstable?
When the mass number of the atom is greater than 82, the atoms are not stable because of the level of binding energy. The atom splits because of the force of repulsion between the particles and the new elements are formed as they reach the new configuration which is stable. ...
Why are isotopes unstable?
Usually, what makes an isotope unstable is the large nucleus. If a nucleus becomes larger enough from the number of neutrons, since the neutron count is what makes isotopes , it will be unstable and will try to ‘shed’ its neutrons and/or protons in order to achieve stability.
Why Uranium is unstable?
The heat released in fission can be used to help generate electricity in power plants. Uranium-235 (U-235) is one of the isotopes that fissions easily. During fission, U-235 atoms absorb loose neutrons . This causes U-235 to become unstable and split into two light atoms called fission products.
Which particle has the least mass?
The part of the atom with the smallest mass is the electron .
Which nucleus is most stable?
It is a stable isotope, with the highest binding energy per nucleon of any known nuclide (8.7945 MeV). It is often stated that 56 Fe is the “most stable nucleus”, but only because 56 Fe has the lowest mass per nucleon (not binding energy per nucleon) of all nuclides.
Which particle has the greatest mass?
The heaviest of these particles is the neutron . Alpha particle has two protons and two neutrons bound together into a particle identical to a helium nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways, that makes its mass to be equal to 2mp + 2mn.
Which nuclei are unstable?
Too many neutrons or protons can upset this balance making the nucleus unstable. Elements with fewer protons, such as the ones near the top of the periodic table, are stable if they have the same number of neutrons and protons. For example carbon, carbon-12 is stable and has six protons and six neutrons.
Are all unstable nuclei radioactive?
All elements with atomic numbers greater than 83 are radioisotopes meaning that these elements have unstable nuclei and are radioactive. Elements with atomic numbers of 83 and less, have isotopes (stable nucleus) and most have at least one radioisotope (unstable nucleus).
What is the most stable element?
There are some 90+ elements of the periodic table that occur naturally in the Universe, but of them all, iron is the most stable. If you fuse lighter elements together to get closer to iron, you gain energy; the same is true if you split heavier elements apart.
Why do nuclei decay?
Nuclear decay occurs when the nucleus of an atom is unstable and spontaneously emits energy in the form of radiation . The result is that the nucleus changes into the nucleus of one or more other elements. ... Nuclear reactions release much more energy—orders of magnitude more—than exothermic chemical reactions.
