| Revision as of 22:01, 18 December 2009 editPhoebe (talk | contribs)Autopatrolled, Event coordinators, Extended confirmed users, Pending changes reviewers19,636 edits ++ link← Previous edit | Revision as of 22:04, 18 December 2009 edit undoPhoebe (talk | contribs)Autopatrolled, Event coordinators, Extended confirmed users, Pending changes reviewers19,636 edits + sentenceNext edit → | ||
| Line 3: | Line 3: | ||
| By sorting formulas according to the number of atoms of each element present in the formula according to these rules, with differences in earlier elements or numbers being treated as more significant than differences in any later element or number — like sorting text strings into ] — it is possible to ] chemical formulas into what is known as '''Hill system order'''. | By sorting formulas according to the number of atoms of each element present in the formula according to these rules, with differences in earlier elements or numbers being treated as more significant than differences in any later element or number — like sorting text strings into ] — it is possible to ] chemical formulas into what is known as '''Hill system order'''. | ||
| The Hill system was first published by ] of the ] in 1900. | The Hill system was first published by ] of the ] in 1900. It is commonly used in chemical databases and printed indexes to sort lists of compounds. | ||
| ==Example== | ==Example== | ||
Revision as of 22:04, 18 December 2009
The Hill system is a system of writing chemical formulas such that the number of carbon atoms in a molecule is indicated first, the number of hydrogen atoms next, and then the number of all other chemical elements subsequently, in alphabetical order. When the formula contains no carbon, all the elements, including hydrogen, are listed alphabetically.
By sorting formulas according to the number of atoms of each element present in the formula according to these rules, with differences in earlier elements or numbers being treated as more significant than differences in any later element or number — like sorting text strings into lexicographical order — it is possible to collate chemical formulas into what is known as Hill system order.
The Hill system was first published by Edwin A. Hill of the United States Patent and Trademark Office in 1900. It is commonly used in chemical databases and printed indexes to sort lists of compounds.
Example
The following formulas are written using the Hill system, and listed in Hill order:
- BrH
- BrI
- CH3I
- C2H5Br
- H2O4S
References
- Edwin A. Hill (1900). "On A System Of Indexing Chemical Literature; Adopted By The Classification Division Of The U. S. Patent Office". J. Am. Chem. Soc. 22 (8): 478–494. doi:10.1021/ja02046a005.
External link
- Hill notation example, from the University of Massachusetts Lowell libraries