Chemical properties of tungsten

At room temperature, similar to chromium and molybdenum, tungsten is not corroded by the atmosphere. At high temperatures, however, it becomes more susceptible to corrosion, reacting with many nonmetals and often producing interstitial and nonstoichiometric products. In the presence of oxidizing agents such as KNO3 or KClO3, molten alkali rapidly corrodes tungsten to form WO4²⁻.

From the perspective of the chromium group to which tungsten belongs, Mo and W are very similar to each other and exhibit significant differences from the lightest element, Cr. This is mainly reflected in the relative stability of their oxidation states, which range from +6 to -2. The stability of the oxidation states in this group has been mentioned above. Furthermore, although chromium (VI) tends to form oxypolyacid anions, its diversity is far less than that of polymolybdates and polytungstates. The +5 and +4 oxidation states mainly manifest as unstable intermediates for chromium; while for molybdenum and tungsten, they provide quite important aqueous solution chemistry. Chromium's most stable oxidation state is +3, and its coordination chemistry, resulting from its symmetrical t2g³ configuration, is second only to cobalt (III) in abundance, while there is no corresponding part in the chemistry of molybdenum or tungsten.