digplanet beta 1: Athena
Share digplanet:


Applied sciences






















Relative abundance of elements.png

In chemistry, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomic weight listed for the element in the periodic table. The abundance of an isotope varies from planet to planet, and even from place to place on the Earth, but remains relatively constant in time (on a short-term scale).

As an example, uranium has three naturally occurring isotopes: 238U, 235U and 234U. Their respective natural mole-fraction abundances are 99.2739–99.2752%, 0.7198–0.7202%, and 0.0050–0.0059%.[1] For example, if 100,000 uranium atoms were analyzed, one would expect to find approximately 99,274 238U atoms, approximately 720 235U atoms, and very few (most likely 5 or 6) 234U atoms. This is because 238U is much more stable than 235U or 234U, as the half-life of each isotope reveals: 4.468×109 years for 238U compared to 7.038×108 years for 235U and 245,500 years for 234U.

Exactly because the different uranium isotopes have different half-lives, when the Earth was younger, the isotopic composition of uranium was different. As an example, 1.7 billion years ago the NA of 235U was 3.1% compared to today's 0.7%, and for that reason a natural nuclear fission reactor was able to form, something that cannot happen today.

However, the natural abundance of a given isotope is also affected by the probability of its creation in nucleosynthesis (as in the case of samarium; radioactive 147Sm and 148Sm are much more abundant than stable 144Sm) and by production of a given isotope by natural radioactive isotopes (as in the case of radiogenic isotopes of lead).

Deviations from natural abundance[edit]

It is now known from study of the sun and primitive meteorites that the solar system was initially almost homogeneous in isotopic composition. Deviations from the (evolving) galactic average, locally-sampled around the time that the sun's nuclear burning began, can generally be accounted for by mass fractionation (see the article on mass-independent fractionation) plus a limited number of nuclear decay and transmutation processes.[2] There is also evidence for injection of short-lived (now extinct) isotopes from a nearby supernova explosion that may have triggered solar nebula collapse.[3] Hence deviations from natural abundance on earth are often measured in parts per thousand (per mil or ‰‰) because they are less than one percent (%). The single exception to this lies with the presolar grains found in primitive meteorites. These bypassed the homogenization, and often carry the nuclear signature of specific nucleosynthesis processes in which their elements were made.[4] In these materials, deviations from "natural abundance" are sometimes measured in factors of 100.

See also[edit]

Footnotes and References[edit]

  1. ^ Uranium Isotopes, retrieved 14 March 2012 
  2. ^ Robert N. Clayton (1978) Isotopic anomalies in the early solar system, Annual Review of Nuclear and Particle Science 28:501–522.
  3. ^ Ernst Zinner (2003) An isotopic view of the early solar system, Science 300:5617, 265–267.
  4. ^ Ernst Zinner (1998) Stellar nucleosynthesis and the isotopic composition of presolar grains from primitive meteorites, Annual Review of Earth and Planetary Sciences 26:147–188.

External links[edit]

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Natural_abundance — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
390395 videos foundNext > 

Atomic Mass: How to Calculate Isotope Abundance

To see all my Chemistry videos, check out http://socratic.org/chemistry How do you determine and calculate isotope abundance when you know the relative atomi...

Seth on Embracing your Natural Abundance by Jane Roberts

Seth discusses the importance of embracing your own natural abundance. This audio clip is from the Seth Audio Collection, Volume 1, Disc 1. For more informat...

Natural abundance, the universe is abundant in nature

Life IS abundance. Life IS a miracle. Life IS infinite~ Yes we are living in a world of contrast. Yes we experience separation, duality, preference, pain, pl...

Ahhh... Natural Abundance! Sept 27, 2013 - CindyEyler Vlog

40 Day Manifesting Breakthrough Video eCourse: http://www.cindyeyler.com/manifesting-breakthroughs/ http://www.CindyEyler.com http://SoulTravelEgypt.WordPres...

Calculating Isotope Abundance using Atomic Mass

webpage-http://www.kentchemistry.com/links/AtomicStructure/atomicmasscalc.htm This is a more challenging problem using atomic mass. I show you haw to calcula...

Calculating the Mass for Isotopes with Natural Abundance

Description: An example problem demonstrating how to calculate the mass of a specific isotope given the natural abundance of the isotopes and one isotope mas...

Livity on Point Episode 7: Natural Abundance

Mango season is upon us! In some parts of Point, you can't take a walk without stepping on a mango carpet. The bounty is so real, you could take a bite of on...


A powerful one day action packed, fun filled hands on seminar that will help you shatter your perceived limitations and allow you to see the infinite opportu...

Natural Abundance, The Lessons Learned, Applying Them

Natural Abundance, The Lessons Learned, Applying Them To Improve Human Settlements/Communities here is some health/nutrition info on mulberry's http://lifest...

Bashar on Simplicity, Abundance and The Natural Self.

instead of chasing your life around trying to get where you need to go.......start allowing all you need and want to come to you.

390395 videos foundNext > 

36 news items


Mon, 15 Sep 2014 08:56:15 -0700

Phosphorus is abundant in several chemical substances such as DNA and biological membranes. The 31P nucleus is one of the key isotopes of phosphorus owing to its 100% natural abundance and wide range of chemical shift. In biological NMR ...


Mon, 15 Sep 2014 08:56:15 -0700

The 19F nucleus is one of the key nuclei for NMR spectroscopy. Its NMR sensitivity is very high because of its 100% natural abundance and high frequency. In the pharmaceutical industry, organofluorine compounds are used often and fluorine is used as a ...
Lexology (registration)
Mon, 15 Sep 2014 05:00:00 -0700

... also known as stable isotopes, to determine the origins of drug products and pathways to help pharmaceutical companies and law enforcement authorities combat Intellectual property infringement,” says Jasper. “The distribution of natural-abundance ...
Fri, 12 Sep 2014 08:47:43 -0700

The headspace was then set to either 100% 13C-CO2 (13CO2 treatment; >99 atomic percent 13C; Sigma-Aldrich, St Louis, MO, USA) or 100% natural abundance CO2 (unlabeled control treatment; Linde Gas, Pullach, Germany). This procedure was repeated ...
Elmwood Park Elm Leaves
Mon, 08 Sep 2014 14:22:30 -0700

Why is their so much poverty on a planet that as an abundance of natural resources, resources which, if shared equally and fairly, would provide natural abundance for all? Why is this the way of the world instead of how it could be, the way it was ...

Alaska Dispatch

Alaska Dispatch
Tue, 09 Sep 2014 18:16:38 -0700

Values embrace protecting natural predator/prey dynamics as well as natural ecosystems and processes, including the natural abundance, diversity, distribution, and behavior of wildlife. These values are not more important than the state's legal ...


Fri, 12 Sep 2014 03:04:26 -0700

One of the most promising candidates for next-generation power sources, Li-S battery is with very high theoretical energy density of 2600 Wh kg-1, natural abundance of element sulfur, and environment friendly as well. "We try to enhance the cyclic and ...
Atlanta Journal Constitution
Fri, 05 Sep 2014 20:56:15 -0700

We are blessed by Georgia's natural abundance of water resources, and with 70,150 miles of rivers, streams, lakes and wetlands, we are all within community reach of some variety of waterway. As we rely on these resources for drinking water, and enjoy ...

Oops, we seem to be having trouble contacting Twitter

Talk About Natural abundance

You can talk about Natural abundance with people all over the world in our discussions.

Support Wikipedia

A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia. Please add your support for Wikipedia!