 This similarity results in nearly identical chemical behavior and in the formation of similar chemical compounds . The chemistry of hafnium is so similar to that of zirconium that a separation on chemical reactions was not possible ; only the physical properties of the compounds differ . The melting points and boiling points of the compounds and the solubility in solvents are the major differences in the chemistry of these twin elements . Titanium is considerably different from the other two owing to the effects of the lanthanide contraction . 
