How has the abundance of hydrogen changed in the universe since the Big Bang?

October 10th, 2009 | by admin |

1) How has the abundance of hydrogen changed in the universe since the Big Bang?

2) Why are the natural abundances of Tc and Pm recorded as 0?

Thanks

The element is determined by the # of protons not the # of Neutrons. The isotope is determined by the # neutrons. Hydrogen without Neutrons is Hydrogen. Hydrogen with a neutron is deuterium, and if it has 2 neutrons it is called Tritium. Helium is produced in the first stage of a stars life cycle. 2 Hydrogen atoms (this includes deuterium and tritium) fuse together to yield helium and energy as well as a slight loss of mass. In later stages of a stars life cycle it starts producing ever heavier elements until if it is massive enough it goes supernova and a whole spectrum of elements are developed. As the universe ages more and more of the hydrogen is used up, but Hydrogen is still the most abundant element in the Universe.

Tc Technetium goes through beta decay and is used in nuclear medicine for diagnostic tests. It is the lightest element with no stable isotopes.

Pm Promethium is also a beta emitter.

On earth Tc and Pm are products of the nuclear age, but they do exist in large stars in their later life cycles ie Red Giant stage through supernova, but because none of their isotopes are radiologically stable they do not last long in geological terms. The longest living Tc half life is 4.2 million years. That sounds like a long time but compared to the Earths age of about 4 billion years that is not very long therefore no matter how much had existed early on in Earths history, almost all of it would be long gone by now. Pm is even worse with a half life of about 17 years.

  1. 3 Responses to “How has the abundance of hydrogen changed in the universe since the Big Bang?”

  2. By ms. jujubee on Oct 10, 2009 | Reply

    1) I am not sure about the answer to this question. One would think that the abundance of hydrogen would have decreased because many hydrogen atoms have formed heavier elements during the formation of stars and planets.

    2) Tc and Pm are synthetic elements created in laboratory, being extremely unstable, they often last less than a second. Hence their natural abundancy is zero.
    References :

  3. By freywayne on Oct 10, 2009 | Reply

    HYDROGEN IS THE MOST ABUNDANT ELEMENT IN THE UNIVERSE IT CAN BE CONVERTED TO HELIUM BY ADDING A NEUTRON TO THE NUCLEUS, HYDROGEN HAS NO NEUTRON IN IT’S NUCLEUS. THE OTHER TWO ELEMENTS ARE FROM THE TAMPERING OF MAN
    References :

  4. By drmanjo2010 on Oct 10, 2009 | Reply

    The element is determined by the # of protons not the # of Neutrons. The isotope is determined by the # neutrons. Hydrogen without Neutrons is Hydrogen. Hydrogen with a neutron is deuterium, and if it has 2 neutrons it is called Tritium. Helium is produced in the first stage of a stars life cycle. 2 Hydrogen atoms (this includes deuterium and tritium) fuse together to yield helium and energy as well as a slight loss of mass. In later stages of a stars life cycle it starts producing ever heavier elements until if it is massive enough it goes supernova and a whole spectrum of elements are developed. As the universe ages more and more of the hydrogen is used up, but Hydrogen is still the most abundant element in the Universe.

    Tc Technetium goes through beta decay and is used in nuclear medicine for diagnostic tests. It is the lightest element with no stable isotopes.

    Pm Promethium is also a beta emitter.

    On earth Tc and Pm are products of the nuclear age, but they do exist in large stars in their later life cycles ie Red Giant stage through supernova, but because none of their isotopes are radiologically stable they do not last long in geological terms. The longest living Tc half life is 4.2 million years. That sounds like a long time but compared to the Earths age of about 4 billion years that is not very long therefore no matter how much had existed early on in Earths history, almost all of it would be long gone by now. Pm is even worse with a half life of about 17 years.
    References :
    http://en.wikipedia.org/wiki/Promethium

    http://en.wikipedia.org/wiki/Technetium

    http://abacusscience.com/periodictable.html

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