Skip to main content Accessibility help
×
Hostname: page-component-848d4c4894-v5vhk Total loading time: 0 Render date: 2024-06-23T12:40:33.327Z Has data issue: false hasContentIssue false

1 - Isotopes: weights and abundances

Published online by Cambridge University Press:  04 September 2009

Igor Tolstikhin
Affiliation:
Kola Scientific Centre, Russian Academy of Sciences
Jan Kramers
Affiliation:
Universität Bern, Switzerland
Get access

Summary

Introduction: nuclei and their behaviour

Atoms are the smallest units of matter that characterize a chemical element. An atom consists of a positively charged core or nucleus and negatively charged electrons orbiting around the core. In nuclear physics, a host of different particles is known to make up atomic cores, but for the purpose of cosmochemistry and geochemistry the simplified model suffices, in which we consider just two kinds of nuclear particles (nucleons): positively charged protons, p, and neutral neutrons, n. For a neutral atom the number of protons in the core, Z (the atomic number), is equal to the number of electrons around it. As Z determines the electron configuration and therefore the chemical behaviour, a family of atoms of equal Z constitutes a chemical element. Such a family generally includes nuclei with a varying number of neutrons, N. The atomic mass number A = Z + N, the total number of nucleons, then varies accordingly. Atoms of an element that have different values of N (and therefore A) are called isotopes, a term with Greek roots indicating that these different nuclides occupy the same position in the periodic table. The lightest element, hydrogen, includes three isotopes, 1H, 2H (D) and 3H, having 0, 1 and 2 neutrons in the core, respectively. Most elements consist of a larger number of isotopes; therefore the approximately 100 currently known elements include approximately 1000 isotopes.

Many isotopes exist indefinitely, at least in normal conditions, and these are known as stable isotopes, S.

Type
Chapter
Information
The Evolution of Matter
From the Big Bang to the Present Day
, pp. 7 - 18
Publisher: Cambridge University Press
Print publication year: 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×