Sentence:  **f appeared to be well suited for the study of these matters , since it is a normal <WSD>paramagnet</WSD> , with three unpaired electrons on the chromium , its crystal structure is very simple , and the unknown position of the hydrogen in the strong **f bond provides structural interest . 
Meaning of the word marked with <WSD> tags:  magnet made of a substance whose magnetization is proportional to the strength of the magnetic field applied to it