All group 5 metals are normally found in nature as oxide ores that contain the metals in their highest oxidation state (+5). Because of the lanthanide contraction , the chemistry of Nb and Ta is so similar that these elements are usually found in the same ores. Chemistry of Dubnium Dubnium (Db) is a transactinide element and is highly radioactive. The most stable known isotope, dubnium-268, has a half-life of just above a day, which greatly limits the extent of possible research on dubnium. Dubnium does not occur naturally on Earth and is produced artificially. Chemistry of Niobium Pure niobium looks much like steel but resists corrosion better due to a thin coating of oxide that forms on all exposed surfaces. The only acid that attacks Nb at room temperature is HF. Above 200° the metal becomes more reactive. Chemistry of Tantalum Tantalum is a heavy, gray metal that resembles the more expensive platinum in many respects and is sometimes used as an economical substitute for that element. The metal comprises only 0.0002% of the earth's crust. Tantalum alloys are corrosion and wear resistant and find use in dental and surgical tools. Tantalum oxide is used in some electronic components and a composite of tantalum carbide (TaC) and graphite is one of the hardest materials ever produced. Chemistry of Vanadium Vanadium (V) takes its name from the Scandinavian goddess Vanadis and was discovered in 1801 by Andrés Manuel del Rio. It was isolated in 1867 by Henry Roscoe as a silvery-white metal that is somewhat heavier than aluminum but lighter than iron. It has excellent corrosion resistance at room temperature. Group 5 Elemental Properties