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Q: atomic mass vs atomic number ( Answered,   1 Comment )
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 Subject: atomic mass vs atomic number Category: Science Asked by: michelazar-ga List Price: \$2.00 Posted: 28 Feb 2005 20:08 PST Expires: 30 Mar 2005 20:08 PST Question ID: 482668
 `exists some relation between the atomic mass and the atomic number?`
 ```Hi, thank you for submitting your question to Answers.Google, I hope I can provide the information you are seeking. Yes, there is a definite linkage. The atomic number of an element is the number of protons (hence the number of electrons) associated with the atom. The reason you see integers describing the atomic number is that all atoms with the same number of protons are the same element. Isotopes of the element have different numbers of neutrons in the nucleus. The atomic weight of an element is the average weight of the nucleus which includes the normally occurring percentage of each isotope for the element. http://www.sparknotes.com/chemistry/fundamentals/periodictable/section2.rhtml For example, Carbon is almost all (99%) carbon-12. The atomic number is 6 meaning there are six protons. The atomic weight is 12.01115? because there are few other carbon isotopes other than the one where there are 6 protons and 6 neutrons. http://www.britannica.com/ebi/article?tocId=234137 The connection between the two numbers is complex but not that difficult to understand in general terms. For elements of low atomic number a nucleus is most stable when the number of neutrons and protons are about equal. When the number of neutrons is different from the number of protons the nucleus generally becomes more unstable (radioactive) and will spontaneously decay into other elements. This 1:1 ration is not an exact relationship and alters significantly as the atomic number increases. The higher the number of protons, the higher the ratio of protons required for stability, going up near 2:1 neutrons:protons at the higher numbers and even higher. A chart of this is referred to as the belt of stability. http://www.faculty.de.gcsu.edu/~rfietkau/1212%20CH%2021%20BLB%20U04.pdf http://www.wwnorton.com/chemistry/overview/ch2.htm http://www.chemistrycoach.com/nuclearchem.htm You can find more information (at a considerably more complex level) at http://www.blazelabs.com/f-p-develop.asp and http://main.chem.ohiou.edu/courses/153/StudyPrep/Ch24A.pdf Thank you again for turning to Answers.Google for help.```
 ```Broadly speaking, the higher one is, the higher the other is. Your question, phrased another way, might be, what determines the number of neutrons that can combine with a given number of protons to form a stable nucleus? It's a complex issue. http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/neutexc.html http://universe-review.ca/F14-nucleus.htm```