nuclear fission and fusion

[mollykins]

whats the difference, i don't understand . . . .

[ttfn]

Friday is traditionally fish 'n' chips day

[bigfoot3000]

Lol, i like that ttfn!

[factor-fiction]

Fission involves splitting
Fusion involves joining together.
This page is useful.
http://www.bbc.co.uk/...learfissionrev2.shtml

[mollykins]

and talking about elements, does density have a relationship with the state of an element at any given temperature? so would all the densist materials be solid then quite dense be liquid then really undense elements be gases? And does this link with relative atomic mass, or does it depend on the molecule size? Or is this going to be to confusing to explain?

[factor-fiction]

And one was a dance group on BGT

[mollykins]

aahhhh . . . are you some kind of sciency genius person factor?

[ChuckFickens]

Somebody doing GCSE science doesn't know the basic difference between fusion and fission, shocking!!

[ttfn]

Surely fission is sticking together or why would they have to batter the cod?

[mollykins]

I was getting confused and physics isn't my forte.

[bigfoot3000]

Also help here mollikins. http://www.wisegeek.c...ission-and-fusion.htm

[mollykins]

thanks.

factor, you don't strike me as being oldest enough to be retired yet you're on this site during the day, unless you're a teacher . . . .?

[mollykins]

old enough

[jake-the-peg]

Fission is splitting up large elements like Uranium into smaller elements and releasing energy because the energy needed to hold together the smaller elements is less.

Fusion is sticking together light elements like Hydrogen to make heavier elements and getting energy out that way.

How can you get energy by splitting and sticking together?

Well there's a basically a curve - the most stable is Iron. splitting heavy elements until you get to iron gives you energy, fusing light elements until you get to Iron does likewise

[mollykins]

Is that similar to working out endo and exothermic reactions?

[jake-the-peg]

What makes an elenent a solid liquid or gas is mostly about its chemistry and how strong the bonds between elements.

The density of a particular element is complicated but generally goes up with the atomic mass.

There are some really complex relationships. Such as the reason Mercury is a metal and yet liquid at room temperature - it's to do with reletivistic effects of the electrons in this particular configuration

[mollykins]

Ahh i'd forgotten about bonds as doubles are stronger meaning two molecules that have the same mass could be diferent states of matter if they had different bond strengths, does it also vary with covalent and ionic bonding?

[jake-the-peg]

Yes they are in effect exo- and endo thermic reactions but nuclear reactions not chemical ones.

They are the reason we have supernovae.

Stars are fusing hydrogen to create energy which balances the gravity.

They go through various cycles but in the end they run out of light materials and try to create iron - endothermic.

All of a sudden there is nothing balancing the gravity and they fall in on themselves in a titanic explosion - enough to create all the other elements.

The iron in your blood was created in an explosion just like that

[mollykins]

and that's why we are made out of star dust . . . .

[beso]

Stars fuse hydrogen until it gets low in supply. Then they start fusing helium into various elements mostly up to up to oxygen and asome selected heavier elements. However the radiation pressure of these reactions is very much lower than the hydrogen reaction and cannot resist the gravitation.

Most of elements heavier than oxygen form when lighter elements are utterly crushed together as the gravitational implosion bottoms out and the shock wave bounces out into a supernova.

This page has a good description.

http://www.astrophysi...ics/stars/Fusion.html