Elements

[Teddy]

Hi all

The other night prof Brian cox on wonders of the univers said there were 92 elements. I have heard there are more and are so on the periodic table I looked at on the web....

So what's the difference, can someone please enlighten me,

Cheers

[lukebl]

Good question. I thought there were at least 118:

[PreludeToADream]

There are 92 "natural" elements, i.e. ones that are naturally occurring in our environment. Other elements can be made but they're unstable. That's my understanding of it anyway.

[Duns]

Yes PreludeToaDream has got the amswer. Only 92 naturally occuring - the others are synthesised and because of the large size of the nuclei they are unstable and decay.

[Teddy]

Cheers for that

How are these other elements formed ??

[Capricorn]

Nuclear fusion, uncontrolled it is a hydrogen bomb.

Controlled it is a partical accelerator/cyclotron like Cern.

They can create particals and see them disintegrate into simpler elements.

[661-pete]

This figure is not quite the definitive answer. I think the number '92' crops up because it is the atomic number of Uranium, which is the highest-numbered element naturally occurring in significant quantities in the Earth's crust.

The exact number of elements which can be said to exist, depends on how exactly you define the word 'exist'. Some of the transuranic elements (those with numbers above 92) have only been synthesised in the quantity of a few atoms, lasting for only a minute fraction of a second. It's debatable whether these elements ever really had any true existence. The number currently goes up to 118 ("Ununoctium").

And of the elements below 92: four of them (Technetium, Prometheum, Astatine and Francium) are so rare as to be to all intents and purposes non-existent in the Earth's crust (there is said to be less than an ounce of Astatine in the Earth at any one time). All four are highly radioactive and decay away before you can get to them! However synthetic Technetium is widely used in medical equipment.

On the other hand, two of the transuranic elements: Neptunium and Plutonium, originally thought to be purely synthetic, are now known to occur naturally in small quantities in the Earth, as decay products in uranium ores.

Synthetically made plutonium is widespread and its applications in the nuclear and weapons industries are only too well-known.

Americium, another purely synthetic element, is the one most ordinary consumers are likely to get close to. If you have any ionisation-type smoke detectors in your house, they will contain a minute amount of Am-241 as a radiation source. But don't worry! The amount of radiation dose you could get from a smoke detector, is less than you'd get from eating a banana!

[ChrisThePuma]

I didn't know bananas were radioactive?

[Teddy]

Brilliant. For some reason at the moment I find the elements a fantastic topic. Reading your posts have really helped. Its really strange that with one simply comment from mr cox I have now found out so much more. It's not a simple as his passing comment makes out Fascinating !

[661-pete]

I didn't know bananas were radioactive?

Banana equivalent dose - Wikipedia, the free encyclopedia

[Macavity]

In my young days, I was seduced by a (bargain bin) paperback by Glenn T Seaborg, and always used to follow the progress of (new) element synthesis with fascination. Would we ever chance on one that had significant stability to have useful bulk properties. Maybe not, with the general "shortage" of neutrons.

Island of stability - Wikipedia, the free encyclopedia

But one can dream. I always fancied a heavy homologue of the inert gases

in element 118. An "noble" (relatively inert) liquid - Or solid, even:

Ununoctium - Wikipedia, the free encyclopedia

[G6RAR]

You could have a listen to Tom Lehre's, "The Elements Song"