Some Physics Questions

Nehpets

Found this definition on skool.ie:

Radioactive decay
The spontaneous disintegration of radioactive nuclei into nuclei of other elements.

What does the "into nuclei of other elements" mean? Also, is that definition good enough for in an exam?

Half life
The time taken for one half of a radioisotope to decay or change into another element.

What does it mean "change into another element"?

tolosenc

My pretty basic understanding of radiation (basically, the nuclues throws out potons, right?) would suggest to me that changing element occurs when the nucleus is sufficiently depleted so that the make up of the nucleus is the same as that of another element.

Mushy

For the first one, each element has a nucleus, electrons and protons. So im guessing that "into the nuclei of other elements" means that its mixing with nuclei of different elements. Thats my guess but Im only doing Ordinary so that might be way off.

Nehpets

but what are the other elemets?

tolosenc

Any other element. You'll probably just be asked to define it, and if there's a formula (haven't done that section yet) you'll be given all the stuff you need.

Nehpets

cool, thanks.

and another question, nuclear fission is caused by a slow moving neutron hitting and splitting a nucleus. Where does the neutron come from?

tolosenc

Another (possibly radioactive) atom? Anywhere?

Nehpets

oh ok.. lol

ZorbaTehZ

What does the "into nuclei of other elements" mean? Also, is that definition good enough for in an exam?

Basically, because the nucleus is unstable (because it is radioactive) it can emit radiation in the form of alpha/beta/gamma rays. Depending on which type of radiation, this can result in the restructuring of the nucleus because it is losing neutrons/protons etc. Because the nucleus is now restructured - after emitting the radiation - it is now a different type of element because the atomic number and mass number have changed. Best explained using an example:

226/88 Ra --> 222/86 Rn + 4/2He + ENERGY

(the alpha particle emitted means
that the original nucleus now lacks
2 neutrons and 2 protons. It is now
a Radon atom, changed from a
Radium one.)

(Regarding Half-Life)
What does it mean "change into another element"?

Half-Life is a measure of how long it takes the above mentioned Radioactive Decay to happen, so the change to another element is the change to another nucleus.