Why uranium 238 is stable whereas 235 in unstable?

Answer 1

As we can see the two isotopes have two differant half lifes.

U 235 has a half life of about 700 million year
U 238 has a half life of abotu 4.5 billion years

So U 238 is much more stable than U 235. This is also the reason why it is much mor aboundant. The earth is about 4.6 billions years old. so half of the U238 that existed then remains. On the other hand U 235 has gone through a half life about 7 times, so only about 1% of its original ammount remains. (also a whole bunch decayed even before the earth was formed)

But any who... in the neucleus of the atom there are protons that determin what the atom is. BUT two proton so close together are going to exert a huge force between them. (remeber like charges tend to repell each other, and protons are positivly charged) But there is another force called the weak force. It is like gravity only much stronger and acts over very small distances (like the size of an atomic neucleus)

In this case if you add neutrons to the neucleus they can cause a force that can keep the protons so near to each other.

In the case of U 238 it has 3 extra neutrons in its core, so that is those three extra parctiles that are helping keep the neucleus together. Thus we can see why it is more stable.

Answer 2

Uranium 238

Answer 3

hi asker,
u 'no that the function of neutrons is to act as packing material
for protons to reduce repulsion between the latter.
by normal calculation ,we can fins that U-238 has 146 neutrons
but U-235 has only 143 neutrons.
so there's better packing in U-238 than U-235, so lesser repulsion
and more stability.
we cannot say that U-238 is stable,but comparing U-235,it can
be considered as a stable species.

Answer 4

U238 is not completely stable, it is just less unstable than U235. The reason is that the positive charge of all the protons is constantly trying to push the nucleus apart, but the electrically neutral neutrons interfere with that tendency. Since U238 has 3 more neutrons than U235, it is a little more stable.

Answer 5

The answer can be given by use of Neutron Proton fraction. And also by Binding energy per nucleon. The BE per nucleon of U-235 is less than 7.2 and hence it is unstable. Also if the BE per nucleon is above 8 and less than 8.5 the atom is most stable. Also the answers above are also true! Bye Have a nice day.

Answer 6

uranium 235 has disintegrating properties than uranium 238. it is unstable and have continuous and spontaneous chain reaction, which ends when uranium 235 finished. for more information refer book radioactive elements by R.K. JAIN.

Answer 7

U-238 has undergone intensive therapy.

Answer 8

One of the rule says nucleus that have even number of nucleons are more stable than the nucleus that have odd number of nucleons. It holds for all isotopes

Answer 9

Proton-electron ratio

Answer 10

Both are radioactive, but U235 is fissionable by neutrons.