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Prof Brian Cox mentioned on Wonders of the Universe when discussing chemical elements that Carbon 12 consists of 6 protons and 6 neutrons, he also mentioned that Helium consists of 2 protons and 2 neutrons. He then went on to say that by combining certain elements we can create others - can anyone explain what he means by this with a practical example?

Can I get myself some Carbon and some Helium and somehow combine them? :)

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Brian Cox was talking about stellar nucleosynthesis. In theory you could combine the nucleus of a Helium atom (also called an alpha particle) and the nucleus of a Carbon atom to produce an Oxygen nucleus and some energy in the form of gamma radiation
$$ ^4_2He + ^{12}_6C \rightarrow ^{16}_8O +\gamma$$ This is an alpha process, and does happen inside certain stars.

In practice, you are unlikely to be able to do this personally, as you probably cannot get the nuclei moving fast enough or accurately enough to enable fusion.

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brilliant, that last sentence clarified exactly my query! –  78lro Apr 5 '11 at 11:22

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