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10 Easy Tips for Finding Property Data

This page is meant to be used in conjunction with the Property Data Index.

*Click on a tip for more details*

The Most Efficient Ways to Search Handbooks and Databases
  1. If a handbook is arranged by property, search the index first, then the table of contents.
  2. If a handbook is arranged by the chemical name, search by using one or more of the indexes.
  3. If using an electronic database, search first by the CAS registry number (if available) or use the common name of the chemical.
A Property by Any Other Name is Still the Property
  1. Search all synonyms of the property in each handbook/database.
  2. Search the subject area as well as the property name.
  3. Know what symbol and/or unit of measurement is used for the property.
Chemicals Wear Many Disguises
  1. Molecular Formulas: Know when and how to alphabetize.
  2. Structures: Novices should convert structure diagrams into molecular formulas.
  3. Chemical Names: Be familiar with the different types, where each type is used and how it is indexed.
  4. Registry Numbers: Searching a Number is Much Easier Than Searching a Complex Chemical Name or a Molecular Formula.


The Most Efficient Ways to Search Handbooks and Databases

TIP #1

If a handbook is arranged by property, search the index first, then the table of contents.
Some handbooks are arranged so that each chapter or section is devoted to a specific property, related group of properties, or a subject. There is usually an index in the back of the volume or separate index volume at the end of the set if the handbook is muli-volumed. The index may include either the properties or the compounds or both. The most common form of index has the properties listed in alphabetical order and the compounds or groups of compounds that have property information available are indented under the property. The table of contents may help determine where a specific property is located within the volume. An example of a handbook arranged by property is the CRC Handbook of Chemistry and Physics (QD65 .H3 Science Reference).

TIP #2 If a handbook is arranged by the chemical name, search by using one or more of the indexes.
Other handbooks have the content listed alphabetically by the chemical name. Under each name is the property information. There are usually indexes for names, CAS registry numbers and molecular formulas at the back of the volume, or, for multi-volume works, in a separate index volume at the end of the set. An example of a handbook arranged by chemical name is the Merck Index (RS51 .M4 1996 Science Reserve). There is no way to search by the property name in these types of handbooks.

TIP #3 If using an electronic database, search first by the CAS registry number (if available) or use the common name of the chemical.
Databases are usually searchable by name, CAS registry number and molecular formula. Some databases are searchable by the property name. Most databases require searching the complete name, registry number or molecular formula; a few may permit truncation (sometimes called "wildcards") or allow browsing (being able to see all the names, etc. in alphabetical order). Browsing is very helpful if the exact spelling of the name is unknown. Databases are similar to handbooks that arrange information under the chemical name, so searching is usually done by the chemical name not the property name. An example of a chemical database is http://www.chemfinder.com.


A Property By Any Other Name Is Still The Property

TIP #4

Search all synonyms of the property in each handbook/database.
A property may have several names and some handbooks do not list all the variant names in their indexes or within the information part of an entry. There is no way to know ahead of time which name or names will be used in a handbook.

Examples of synonyms:

Enthalpy of Formation is also called the Heat of Formation
An Extinction Coefficient is also referred to as Molar Absorptivity
Redox is a common shortening of Oxidation-Reduction
Reduction Potentials are also known as Electrode Potentials

If the handbook is arranged by the properties, search all synonyms of the property in the index. If the handbook has little or no indexing, the Table of Contents can be browsed for the property name(s). For handbooks that arrange the information in alphabetical order by the chemical name, look for all synonyms of the property in the information part of the entry for that chemical.

Some dictionaries that may be helpful in finding the synonyms are listed below.

TIP #5 Search the subject area as well as the property name.
Can't find the property by its name? Try looking under the subject.

For example:

Enthalpy of Formation is Thermodynamics
Extinction Coefficient deals with Ultra-Violet Spectroscopy
Reduction Potentials are Electrochemistry

If the handbook is arranged by the properties, look up the subject in the index; if there is little or no indexing, the Table of Contents can be browsed for that subject. For handbooks that are arranged in alphabetical order by chemical name, see if the information part of the entry is divided into subject sections.

Some dictionaries that may list the subject of the term are given below.

TIP #6 Know what symbol and/or unit of measurement is used for the property.
Some handbooks and databases have the data tables or information part of the entries labelled by the symbol and/or units of the property rather than the name of the property. Sometimes these symbols are explained at the top or bottom of tables, at the front of that chapter or section, in an introductory section of the book, or on a separate help page or section of a database. Some dictionaries may list symbols and/or units. Chapter 2 of the CRC Handbook of Chemistry and Physics (QD65 .H3 Science Reference) also has symbols arranged by subject.

Recommended Dictionaries

  • McGraw-Hill Dictionary of Chemistry.
    QD5 .M357 1997 Science Reference
    Gives synonyms and subject field of the properties. Not good for finding symbols or units of a property. Other chemistry dictionaries are on the same shelf as this title.

  • McGraw-Hill Dictionary of Physics.
    QC5 .M424 1997 Science Reference
    Gives synonyms and subject field of the properties. Not good for finding symbols or units of a property. Other physics dictionaries are on the same shelf as this title.

  • Dictionary of Chemistry.
    QD5 .D493x 2000 Science Reference
    Gives synonyms, long descriptions for the property. Usually gives symbol/units. Generally does not give the subject area. Other chemistry dictionaries are on the same shelf as this title.

  • CRC Handbook of Chemistry and Physics
    http://www.asu.edu/lib/resources/db/crcchem.htm
    See Section/Chapter 2 for defintions of scientific terms, plus symbols and terminology for physical and chemical quantities.

  • Harcourt Academic Press Dictionary of Science and Technology
    http://www.harcourt.com/dictionary/
    Good source for finding the subject area. Includes some synonyms. Symbols/units are usually not given. Not as comprehensive a source as dictionaries devoted to one specific subject.




Chemicals Wear Many Disguises

The 109+ elements are the "building blocks" of chemicals. The elements are usually displayed in a periodic table that links elements with similar characteristics in vertical and horizontal rows. Each element has a one or two letter symbol; one letter symbols are always in upper case (ex. K, P, S); two letter symbols are always written with the first letter in upper case and the second letter in lower case (ex. Ar, Co, Na) . Many symbols are derived from foreign languages so the element symbol and the English name do not always match (ex. the symbol for silver is Ag from the Latin "argentum").

Chemical elements combine together to form chemical compounds. There are over 27 million substances identified by Chemical Abstracts Service. (See the latest substance count) But its not just the sheer volume of possible compounds that makes chemistry so challenging, it's also the various ways in which these chemical compounds can be identified. The four ways are: molecular forumula, structure diagrams, names, and registry numbers.

TIP #7 Molecular Formulas: Know when and how to alphabetize.

Molecular formulas describe what elements, and how many of each, make up a compound. Because the formula only accounts for what elements are present and not how those elements are arranged, it is possible for more than one compound (in some cases, hundreds!) to have the same formula. Almost all chemistry handbooks and databases provide an index by molecular formula; however most non-chemistry handbooks/databases do not.

How a molecular formula is written and how it appears in an index depends upon the type of compound.

  • Organic compounds (compounds containing carbon)
    Formulas are always written and almost always indexed with the carbon (C) and hydrogen (H) first and everything else in alphabetical order.

    Examples of organic molecular formulas:

    C2HF

    C6H6Cl6

    C11H9Br

    C9H11NO

    C12H10Cl2Si

    C18H15O4P


  • Inorganic compounds (compounds that do not contain carbon)
    Formulas are written in various formats, however when indexed, they are usually put in alphabetical order.

    Examples of inorganic molecular formulas:

    Written Indexed
    KBr
    BrK
    SO2Cl2
    Cl2OS2
    Pb(H2PO2)2
    H4O4 P2Pb

Searching molecular formulas in databases can be tricky.

  • In chemistry databases, look for a field, index or search box specifically designated for molecular formula searching. The numerical subscripts are usually typed on the same line, e.g., "c6h12o6". When carbon (C) is present, the formula should be entered with the carbon (C) and hydrogen (H) first, and with all other elements in alphabetical order. When carbon (C) is not present, the elements should be entered in alphabetical order. Be aware that some databases require mixed case, e.g., "Si2Sr" instead of "si2sr".

  • In non-chemistry databases, it is best to search for both the molecular formula and the common name of the compound. The formula should be entered in lower case with the numerical subscripts in-line, and the elements in the order that would most commonly be written e.g., "srsi2", unless the database's help page indicates differently.
TIP #8 Structures: Novices should convert structure diagrams into molecular formulas.

Because molecular formulas may not be unique, structure diagrams are used to identify specific compounds. The diagrams show not only what elements are present, but how they are arranged and connected. Structure diagrams may be written in a line or displayed in 2- or 3-dimensional graphics.

Examples of structure diagrams:

structure example #1 structure example #2 structure example #3
structure example #4structure

example #5

structure example #6

Some databases contain structure drawing programs that allow for searching by structure. Because each program may have it's own set of rules and because structure diagrams can be draw in various ways, it is not always obvious how to draw a structure so that it will be correctly interpreted by the database. For those without training in structure drawing, it may be more beneficial (and time economical) to translate the structure into a molecular formula and search by the formula.

TIP #9 Chemical Names: Be familiar with the different types, where each type is used and how it is indexed.

Chemical compounds are most often identified by name; unfortunately, each compound may have many different names. Most handbooks and databases provide access by several names for each compound but each resource may not index all the variant names. There is no way to tell a head of time which name(s) will be used. Names for chemicals are grouped into 3 categories: tradenames, common names (also called generic or trivial names) and chemical (scientific) names.

Examples of names for chemical compounds:

Ibuprofen
Tradenames: Advil
Motrin
Nuprin
Proflex
RD 13621
Common Name: Ibuprofen
Chemical Names: α-methyl-4-(2-methylpropyl)benzeneacetic acid
2-(p-Isobutylphenyl)propionic acid
4-Isobutylhydratropic acid


DDT
Tradenames: Aavero-extra
Agritan
Bosan supra
Citox
Detox
Dibovin
Hildit
Neocidol
Zerdane
Common Names: Dichlorodiphenyltrichloroethane
DDT
Chemical Names: 1,1'-(2,2,2-tricholorethylidene)bis[4-chlorobenzene]
1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane
4,4'-Dichlorodiphenyltrichloroethane

  1. Tradenames

    Tradenames are given to specific products by a manufacturer and appear on the packaging and advertisement for that product. They are usually simple (one or two syllables) so they can be easily remembered, may convey their purpose (ex., "Allegra" is a medication used to control allergy symptoms), and/or may be followed by a number that seems to indicate a specific formulation. Tradenames sometimes can be difficult to distinguish from common names. Tradenames are indexed in handbooks or databases as follows:

    • Almost always found in pharmaceutical resources.
    • Frequently found in resources geared toward a specific industry.
    • Sometimes found in resources geared toward the consumer.
    • Very seldom found in resources geared toward chemists or chemistry students.

    For handbooks or databases that do not contain tradenames, use the following resources to find the common or scientific name.

    • Chemical Tradename Dictionary
      TP9 .A73 1993 Science Reference

    • Gardner's Chemical Synonyms and Trade Names
      TP9 .G286 1999 Science Reference

    • Chemical Abstracts/SciFinder Scholar
      http://www.asu.edu/lib/resources/db/scifinder.htm
      Requires ASUrite ID and Password.

  2. Common Names

    Common names, sometimes called generic or trivial names are usually the best way to locate compounds. These names are generally short and almost every resource indexes them.

  3. Chemical Names

    The chemical or scientific name is designed to convey the exact structure of the compound in an unambiguous manner. It is not uncommon for inorganic compounds, which are relatively simple structures, to have chemical and common names that are the same. Many organic compounds, however, are big and complicated strutures and their names follow suit. Naming conventions for organic compounds have changed throughout the years and an "official" set of nomenclature rules was not universaly adopted until the last half of the 20th century. Consequently, a compound with a complex structure can have several "scientific" names.

    The association that produces the official nomenclature rules is the International Union of Pure and Applied Chemistry (IUPAC). Chemical Abstracts Service (CAS), for the purposes of producing Chemical Abstracts (CA), has a naming system that is based on IUPAC so the CA names are usually similar, if not identical. Some recent chemistry resources list the CAS name as the "official name". If the "official name" is followed by (XCI) were "X" is a number from 1-13, then this is the CAS name -- the CI designation indicates what Collective Index period of Chemical Abstracts that version of the name was first used. For example, (9CI) indicates that the name was first used during the 9th Collective Index period which is 1972-1976.

    Complex chemical names are filed by two different methods, direct order and inverted order. The inverted method is used by Chemical Abstracts and in Chapter 3 (Organic Chemistry) of the CRC Handbook of Chemistry and Physics; this method has the advantage of arranging compounds in a heirarchical, structure-based order. The direct method (used by IUPAC) is found in many handbooks and databases. Except for Chemical Abstracts and Chapter 3 of the CRC, expect to find the names indexed in direct order but be prepared to use the inverted version if the handbook/database appears to index by that method. Compare these lists of the same 9 compounds.

    Direct Inverted
    3,4-didehydropyridine
    2,6-dimethyl-3-nitropyridine
    2,6-dimethyl-4-nitropyridine
    4,6-dimethyl-2-pyridinamine
    2,4-dimethylpyridine
    2,6-dimethylpyridine
    4-ethenylpyridine
    2-methylpyridine
    4-methylpyridine
    2-Pyridinamine, 4,6-dimethyl-
    Pyridine, 3,4-didehydro-
    Pyridine, 2,4-dimethyl-
    Pyridine, 2,6-dimethyl-
    Pyridine, 2,6-dimethyl-3-nitro-
    Pyridine, 2,6-dimethyl-4-nitro-
    Pyridine, 4-ethenyl-
    Pyridine, 2-methyl-
    Pyridine, 4-methyl-

    Note that in both cases, the names are filed alphabetically by the name segments. The alpha-numeric characters (arabic numerals, roman letters, or greek letters) are ignored in the filing unless needed to differentiate two exact name segments/words. For example, see how the dimethylpyridine and the methylpyridine compounds are handled in both lists.

TIP #10 Registry Numbers: Searching a Number is Much Easier Than Searching a Complex Chemical Name or a Molecular Formula.

There are many chemcial registries that exist, mainly for toxicological/hazard reporting to governmental agencies. The most prominent of these registries is the Chemical Abstracts Service Registry. Most recent chemical handbooks and databases index CAS registry numbers.

CAS registry numbers look like this:

528-23-4

80656-12-8

2146-37-4

26530-20-1

3973-62-4

31720-69-1

A CAS registry number is assigned to each specific chemical compound that appears in the chemical literature or as requested by chemical manufacturers to comply with regulatory procedures. Each number always has 3 segments separated by hyphens. The first segment consists of 2 or more numbers which are assigned more or less sequentially; a lower number indicates the compound was registered towards the begininng (1965) and a higher number is more recent. The second segment always is composed of 2 numbers and the third segment is always composed of one number. CAS has a formula to determine if a registry number is plausible, see: Check Digit Verification of CAS Registry Numbers at http://www.cas.org/EO/checkdig.html.

Sometimes CAS registry numbers are followed by P, D, DP or *.

  • Unless you are searching the Chemical Abstracts database, ignore the P, D and DP indicators. These are "limiting codes" that restrict searches to the preparation (P), unspecified derivatives (D) or preparation of unspecified derivatives (DP) for the compound represented by that registry number.

  • The * indicator, however, is important whether searching Chemical Abstracts, handbooks or databases. In the United States, chemical manufacturers are required by law to maintain a "Material Safety Data Sheet" on the substances they produce. A MSDS must include the CAS Registry number for that substance. But some substances are a mixture of unknown/unspecified compounds or have a formulation that may change with each batch or with manufacturer(for example, gasoline); in these instances, Chemical Abstracts Service assigns a registry number with an * so that the substance can be registered but the number is not generally used for searching purposes. Consequently, it may be futile to use this number when searching chemical resources; if anything at all is found, it's usually only to indicate that the substance is a mixture of unspecified compounds. The best place to find information on an * compound is usually the manufacturer's MSDS or go directly to the manufacturer.

Because a number is easier and less time consuming to search in an index than a long list of variant names or a complex chemical name, use CAS registry numbers to search more efficiently. CAS registry numbers are found in many chemistry resources including Chapters 3 (Organic Compounds) and 4 (Inorganic Compounds) of the CRC Handbook and Chemical Abstracts. There are two caveats when using registry numbers for searching purposes. Sometimes Chemical Abstracts Service changes the registry number - handbooks and databases do not always record these changes. Also, numbers are easily misinterpreted - they could be copied wrong, have numbers transposed, or be written illegibly (1 mistaken for 7, 9 mistaken for 4, etc.). Always be prepared to back up a search by registry number with a search by name or molecular formula.



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Linda Shackle
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November 2000; Last Revised: December 6, 2004
URL: http://www.asu.edu/lib/noble/chem/prophelp.htm