What is helim 3?

It's an isotope of helium. It has 1 neutron instead of the normal 2. For more information, see:

Isotope - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Isotope)
Helium-3 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Helium-3)

What is helim 3?
Capuchin is correct that it is an isotope of helium.
You should know that helium has two protons and - normally therefore also - 2 neutrons.
Helium3 however lost one neutron.
Any atom that has a different number of neutrons than it has protons is called an isotope.

You should check the provided link and find out if the characteristics of an isotope are the same or not to a normal atom, and what the specifics of an isotope are...

Success !

:)

Cred: I don't know where you got your idea that "normal" atoms have the same number of protons as neutrons. It's only true for a handful of elements.

Additionally, all of the variations of an element are isotopes - even the most common. For example - Carbon-12, Carbon-13 and Carbon-14 are all isotopes of carbon, Carbon-12 being the main form that we are all familiar with on our toast!

Cred: I don't know ....
I stand corrected...
Have to go to bed before 6 am , I see !

:)

I stand corrected ...
Have to go to bed before 6 am , I see !

:)

You can be forgiven for the mistaken definition of isotope - it's very easy to come away from a chemistry course thinking that carbon-13 and -14 are isotopes of carbon-12, because of the way it's often taught. But that's wrong :)