Chemistry::Elements - Perl extension for working with Chemical Elements use Chemistry::Elements qw(get_name get_Z get_symbol); # the constructor can use different input $element = new Chemistry::Elements $atomic_number; $element = new Chemistry::Elements $chemical_symbol; $element = new Chemistry::Elements $element_name; # you can make up your own attributes by specifying # a method (which is really AUTOLOAD) $element->molar_mass(22.989) #sets the attribute $MM = $element->molar_mass #retrieves the value There are two parts to the module: the object stuff and the exportable functions for use outside of the object stuff. The exportable functions are discussed in EXPORTABLE FUNCTIONS. Chemistry::Elements provides an easy, object-oriented way to keep track of your chemical data. Using either the atomic number, chemical symbol, or element name you can construct an Element object. Once you have an element object, you can associate your data with the object by making up your own methods, which the AUTOLOAD function handles. Since each chemist is likely to want to use his or her own data, or data for some unforesee-able property, this module does not try to be a repository for chemical data. The Element object constructor tries to be as flexible as possible - pass it an atomic number, chemical symbol, or element name and it tries to create the object. # the constructor can use different input $element = new Chemistry::Elements $atomic_number; $element = new Chemistry::Elements $chemical_symbol; $element = new Chemistry::Elements $element_name; once you have the object, you can define your own methods simply by using them. Giving the method an argument (others will be ignored) creates an attribute with the method's name and the argument's value. # you can make up your own attributes by specifying # a method (which is really AUTOLOAD) $element->molar_mass(22.989) #sets the attribute $MM = $element->molar_mass #retrieves the value The atomic number, chemical symbol, and element name can be retrieved in the same way. $atomic_number = $element->Z; $name = $element->name; $symbol = $element->symbol; These methods can also be used to set values, although changing any of the three affects the other two. $element = new Chemistry::Elements('Lead'); $atomic_number = $element->Z; # $atomic_number is 82 $element->Z(79); $name = $element->name; # $name is 'Gold' These functions can be exported. They are not exported by default.

get_symbol()
This function attempts to return the symbol of the chemical element given either the chemical symbol, element name, or atmoic number. The function does its best to interpret inconsistent input data (e.g. chemcial symbols of mixed and single case). use Chemistry::Elements qw(get_symbol); $name = get_symbol('Fe'); #$name is 'Fe' $name = get_symbol('fe'); #$name is 'Fe' $name = get_symbol(26); #$name is 'Fe' $name = get_symbol('Iron'); #$name is 'Fe' $name = get_symbol('iron'); #$name is 'Fe' If no symbol can be found, nothing is returned. Since this function will return the symbol if it is given a symbol, you can use it to test whether a string is a chemical symbol (although you have to play some tricks with case since get_symbol will try its best despite the case of the input data). if( lc($string) eq lc( get_symbol($string) ) ) { #stuff } You can modify the symbols (e.g. you work for UCal ;) ) by changing the data at the end of this module.

get_name()
This function attempts to return the name the chemical element given either the chemical symbol, element name, or atomic number. The function does its best to interpret inconsistent input data (e.g. chemcial symbols of mixed and single case). $name = get_name('Fe'); #$name is 'Iron' $name = get_name('fe'); #$name is 'Iron' $name = get_name(26); #$name is 'Iron' $name = get_name('Iron'); #$name is 'Iron' $name = get_name('iron'); #$name is 'Iron' If there is no Z can be found, nothing is returned. Since this function will return the name if it is given a name, you can use it to test whether a string is a chemical element name (although you have to play some tricks with case since get_name will try its best despite the case of the input data). if( lc($string) eq lc( get_name($string) ) ) { #stuff } You can modify the names (e.g. for different languages) by changing the data at the end of this module.

get_Z()
This function attempts to return the atomic number of the chemical element given either the chemical symbol, element name, or atomic number. The function does its best to interpret inconsistent input data (e.g. chemcial symbols of mixed and single case). $name = get_Z('Fe'); #$name is 26 $name = get_Z('fe'); #$name is 26 $name = get_Z(26); #$name is 26 $name = get_Z('Iron'); #$name is 26 $name = get_Z('iron'); #$name is 26 If there is no Z can be found, nothing is returned. Since this function will return the Z if it is given a Z, you can use it to test whether a string is an atomic number. You might want to use the string comparison in case the $string is not a number (in which case the comparison will be false save for the case when $string is undefined). if( $string eq get_Z($string) ) { #stuff } The package constructor automatically finds the largest defined atomic number (in case you add your own heavy elements).

AUTOLOADing methods
You can pseudo-define additional methods to associate data with objects. For instance, if you wanted to add a molar mass attribute, you simply pretend that there is a molar_mass method: $element->molar_mass($MM); #add molar mass datum in $MM to object Similiarly, you can retrieve previously set values by not specifying an argument to your pretend method: $datum = $element->molar_mass(); #or without the parentheses $datum = $element->molar_mass; If a value has not been associated with the pretend method and the object, the pretend method returns nothing. I had thought about providing basic data for the elements, but thought that anyone using this module would probably have their own data. If there is an interest in canned data, perhaps I can provide mine :) I would like make this module easily localizable so that one could specify other names or symbols for the elements (i.e. a different language or a different perspective on the heavy elements). If anyone should make changes to the data, i would like to get a copy so that i can include it in future releases :) brian d foy <comdog@panix.com>