I learnt that gold was formed due 2 supernova explosion. And that metals heavier than iron r difficult to find

Question

And anyone pl give me a explanation (i am a novice)

Answer 1

Stars generate the heat they need to survive by nuclear fusion - the addition of protons to an atomic nucleus. Thats a bit like forcing like poles of two magnets together - you have to force them together against their mutual repulsion. Once you've forced the proton and nucleus together though they form a new, heavier stable nucleus and in the process release more energy than was required to force them together. However,as successive nuclei get heavier (due to the added protons) the repulsive force gets stronger. Iron won't fuse because it requires more energy to force the proton into the nucleus than is released by forming the next heaviest nucleus. This has devastating consequences for a star because once it has an Iron core it can't produce any more heat to support itself against gravity. In just a few seconds an Iron ball with the mass of our Sun collapses in on itself. This cools rather than heats the core because the Iron nucleii are broken into protons and electrons and that absorbs energy. At the centre of the Iron ball these fuse to form a neutron core and wow does that release energy!! The outer Iron core collapses onto the neutron core (or star cos thats what it now is) and bounces off creating a shockwave travelling at a good fraction of the speed of light away from the core.
Whilst all this is going on, the outer layers of the star haven't even noticed whats happening "down below" because it occurs so fast. In effect there are roughly twelve solar masses of star hanging unsupported in space. This begins to fall due to gravity and what does it meet ? The shockwave coming the other way. When they collide the temperature "goes off the scale". This is where there is enough energy to force protons into Iron nucleii to build heavier elements right up to Gold and beyond.
If you want a really good and more in depth explanation read the book "Stardust" by John Gribbin.

Answer 2

It's true.

The process of fusion that causes stars to emit light and heat works by turning light elements into heavier elements. It starts with Hydrogen (the lightest element) which is turned into Helium (the second lightest element). When enough Helium accumulates, the Helium starts turning into Carbon, and so on. as long as the star is large enough the process will continue all through the various elements.

But it stops at Iron. This is because any fusion reaction that involves Iron makes the star lose energy. Instead of being a reaction that heats and lights the star, Iron fusion sucks the life out of a star. It destroys the balance of the star and the star explodes.

But that explosion is so powerful that in that moment all kinds of fusion can take place as the bits of the star are sent flying in all directions. Some of the Iron can change into all kinds of heavier elements. All elements heavier than Iron are created in these few moments as the star explodes.

But since it is such a short time for these reactions to happen, the amounts of these heavy elements is very small compared to the other lighter elements. That's why gold and other heavy elements are so rare.

Remember that our sun and our solar system are made up of gas and other material that was spewed out by an exploding star long ago. That's why we can have any of these elements at all.

Answer 3

Elements with an atomic mass lower-than or equal-to iron are formed in the cores of stars from the fusion of lighter nuclei. All those reactions give off energy, but as the atomic masses go higher, they give off less energy. Iron is the turning point, as fusion of iron nuclei begins to CONSUME ENERGY. The build-up of iron in a star's core is kind of the beginning of the end for that star.

When that star goes supernova, the collapse is so extreme that weird physics begin to manifest themselves. You can look up "r-process" and "s-process" if you feel inclined. In those processes the unfavorable reaction (forming atomic masses greater than iron) actually happens, whether through an unstable intermediary or not is the main difference between the two processes, I guess.

Answer 4

Both are ture. Here's why:

Nuclear fusion cannot occur with elements heavier than iron without requiring more energy than you put into it. As such, once stars reach this stage, they explode. The energy of this explosion fuels further nuclear reactions, which is resposible for the formation of heavier elements- like gold. Stars big enough to do this are rare, which is why the universe is comprised almost entirely of lighter elments- metal rich places like Earth are not all that common.

Answer 5

Yes, All heavy metals were formed in the core of red giant stars.