Re: Universe has many elements.Do all elements break down into Hydrogen

Dear Mr. McGannon

I gather you teach 7th grad science. You have quite an intelligent and 
curious group.

There are several parts to your question.

By definition an element is a substance that cannot be broken down into 
any simpler substance. As such elements cannot be broken down to hydrogen.

The next part of you question deals with the formation and development of 
the elements. Approximately 15 billion years ago the universe began as an 
extremely hot and dense region of radiant energy. The Big Bang. 
Immediately after the formation, it began to expand and cool. As
the universe cooled, sub atomic particles, known as quarks condensed to 
form nucleons. This process is similar to the way steam condenses to water 
droplets as water vapor cools. Further expansion and cooling allowed the 
neutrons and some protons (hydrogen atoms) to fuse to form helium nuclei.

Substantial quantities of nuclei more massive than hydrogen were not made 
in the Big Bang. After about a billion years, clouds of cold atomic 
hydrogen and helium gas began to be drawn together. As they contracted to 
higher densities the clouds warmed. When the temperature reached a few 
million degrees Kelvin, nuclear reactions began in the cores of these 
massive stars.

Stars the size of the Sun will burn hydrogen into helium until the 
hydrogen is exhausted. At this point the cores of the star contracts and 
heats up until a fusion reaction of three helium nuclei are converted into 
carbon. At this stage the stare is known as a red giant. 

Higher mass stars have higher internal temperatures than our sun and they 
are capable of fusing carbon into oxygen. In very massive stars, the 
fusion reaction can produce successively more massive nuclei all the way 
up to iron. Atoms’ more massive than iron is produced by the capture
of neutrons by atoms during the few moments of the explosion of a super 
nova. The sequence of such a reaction can produce elements all the way up 
to uranium 238.

Some books and articles on the origin of elements are:

Steven Weinberg, the First Three Minutes. Basic Books, New York, 1993

David Lindley, The End of Physics, Basic Books, New York, 1993

Radioactive elements both natural and manmade do under go nuclear decay 
and depending on the type of emission that occurs they do change into 
other elements but only to the stable form in the decay series. For 
naturally occurring radioactive elements they decay back to lead. Man-made 
elements decay back to the next stable element in the series in the 
periodic table.