The methods available may be viewed in a number of ways. The URL used can be visited in a browser, or Get-Member may be used. A subset of the output from Get-Member follows:

PS> $service | Get-Member

Name                MemberType  Definition
----                ----------  ----------
GetElement          Method      SOAP.Element GetElement(string Name)
GetAtomicMass       Method      string GetAtomicMass(string Name)
GetAtomicNumber     Method      int GetAtomicNumber(string Name)
GetElements         Method      SOAP.Element[] GetElements()
GetElementsByGroup  Method      SOAP.Element[] GetElementsByGroup(SOAP.Group group)
GetElementSymbol    Method      string GetElementSymbol(string Name)
SearchElements      Method      SOAP.Element[] SearchElements(SOAP.SearchCondition[] searchConditions)

The preceding  GetElements method requires no arguments and may be called immediately, as shown here:

PS> $service.GetElements() | Select-Object -First 5 | Format-Table

AtomicNumber    Symbol    Name         AtomicMass     Group
------------    ------    ----         ----------     -----
           1    H         Hydrogen     1.00794(4)     Nonmetal
           2    He        Helium       4.002602(2)    NobleGas
           3    Li        Lithium      6.941(2)       AlkaliMetal
           4    Be        Beryllium    9.012182(3)    AlkalineEarthMetal
           5    B         Boron        10.811(7)      Metalloid

Methods requiring string or numeric arguments may be similarly easy to call, although the value the method requires is often open to interpretation. In this case, the name argument may be either an element name or an element symbol. Documentation is difficult to replace when working with web services:

PS> $service.GetAtomicNumber('oxygen')
8

PS> $service.GetAtomicMass('H')
1.00794(4)