Hill notation is a standard way of writing the formula for any chemical compound. Hill notation is NOT unique for a compound. The empirical formula for any compound is written in correct Hill notation.
First, Count All Carbon Atoms and record. C10
Second, Count all Hydrogen atoms and record: C10H23
Third, determine all other elements in compound. Count each and record in alphabetical order. C10H23N.
When determining counts from a structural drawing, CAREFULLY count H atoms!!
Counting all the Carbon atoms: C6
Counting all the Hydrogen atoms: C6H18
Determining all the other elements in the compound. Count each and record in alphabetical order.
For any formula, if C is present, it always comes first. It is followed by H, if there are any. All other elements follow C (and H) in alphabetical order. If there is no C in the compound, all elements are listed in alphabetical order, including H.
Hill order is the organization of formulas in Hill notation. It allows compounds to be methodically indexed. All compounds containing both Carbon and Hydrogen atoms have those listed first, with all other elements following, in alphabetical order. All compounds with C, have C listed first. All compounds without C have elements listed in alphabetical order. Numbers of atoms are arranged in ascending order, so that all C2 compounds appear before any C3.
The two examples below will help you understand the order. Gary Wiggins was a prominent chemistry Librarian, at Indiana University. Edwin Hill of the US Patent Office came up with the idea and published the paper in 1900, in JACS, vol 22, p. 478-494.
|Wiggins Book||Edwin Hill paper|