If the proper behavior is to throw an exception, then the unit test should expect it

Change-Id: Ia47ea485b73ecec0d9259272aef0b111e142d022
Signed-off-by: John May <john.wilkinsonmay@gmail.com>
Set atomic numbers when creating an element from a symbol

Change-Id: Ibc96f55efb6922113e652b9ea7177390ec421199
Signed-off-by: John May <john.wilkinsonmay@gmail.com>