Hafnium compounds

Hafnium compounds are compounds containing the element hafnium (Hf). Due to the lanthanide contraction, the ionic radius of hafnium(IV) (0.78 ångström) is almost the same as that of zirconium(IV) (0.79 angstroms).^[1] Consequently, compounds of hafnium(IV) and zirconium(IV) have very similar chemical and physical properties.^[1] Hafnium and zirconium tend to occur together in nature and the similarity of their ionic radii makes their chemical separation rather difficult. Hafnium tends to form inorganic compounds in the oxidation state of +4. Halogens react with it to form hafnium tetrahalides.^[1] At higher temperatures, hafnium reacts with oxygen, nitrogen, carbon, boron, sulfur, and silicon.^[1] Some compounds of hafnium in lower oxidation states are known.^[2]

^ ^a ^b ^c ^d Cite error: The named reference lanl72 was invoked but never defined (see the help page).
^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 971–975. ISBN 978-0-08-037941-8.

[lanl72-1] Cite error: The named reference lanl72 was invoked but never defined (see the help page).

[2] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 971–975. ISBN 978-0-08-037941-8.

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