In chemistry, the IUPAC group 5 elements are the vanadium group elements. These are vanadium (V), niobium (Nb), tantalum (Ta), and dubnium (Db). Here is a look at the common properties shared by these elements, their uses, and their sources.
Disambiguation – Group 5 vs Group V
The group 5 elements are not presently the same as the group V elements, despite “5” and “V” technically being the same number! Group 5 refers to the modern IUPAC system of grouping elements, which goes by their column in the periodic table. Mendeleev’s periodic table referred to these elements as group V. But, Mendeleev’s table also classified the pnictogens or nitrogen group as group V.
The CAS numbering system (US) refers to these elements as VB, while the old IUPAC system (Europe) refers to these elements as group VA. The CAS system calls the nitrogen group VA, while the old IUPAC system calls the nitrogen group VB.
The modern IUPAC groups, using Arabic numbers (5 instead of V) removes all this ambiguity. Just be aware, when reading older texts, the numbering system has not been consistent over time.
Group 5 Element Properties
The group 5 elements are all transition metals or d-block elements. The lighter three elements (vanadium, niobium, and tantalum) share many similar properties. They are refractory metals, which are hard and resist wear and heat. All three are silver-colored reactive metals that form oxide layers in air that prevent further reaction. The group 5 elements have high melting points (1910 °C, 2477 °C, 3017 °C, for vanadium, niobium, and tantalum, respectively).
Dubium, in contrast, is not found in nature and only exists as radioactive isotopes. Its most stable isotope, dubnium-268, has a half-life of 29 hours.
Like other transition metals, the group 5 elements display multiple oxidation states and form numerous inorganic compounds. The +5 oxidation state is most common, with decreasing stability accompanying lower oxidation states.
Members of an element group typically share similar electron configuration patterns. This is somewhat true of the group 5 elements, too, although niobium does not adhere to the trend.
| Element | Atomic Number | Electrons per Shell |
|---|---|---|
| Vanadium | 23 | 2, 8, 11, 2 |
| Niobium | 41 | 2, 8, 18, 12, 1 |
| Tantalum | 73 | 2, 8, 18, 32, 11, 2 |
| Dubnium | 105 | 2, 8, 18, 32, 32, 11, 2 |
Discovery
Mexican mineralogist Andrés Manuel del Río discovered vanadium in the mineral vanadinite in 1801. English chemist Charles Hatchett discovered niobium that same year. Anders Gustav Ekeberg discovered tantalum in 1802, although it was not proven to be a different element from niobium until 1846. The Joint Institute for Nuclear Research first synthesized dubnium in 1968 by bombarding americium-243 with neon-22.
Naming
The first three elements are named for mythological figures. Vanadium takes its name for the Scandinavian goddess of love, Vanadis. Niobium is named for Niobe, from Greek mythology. Likewise, tantalum is named for Tantalus from Greek mythology.
Dubnium is named for Dubna, Russia, which was the site of its discovery.
Biological Roles and Toxicity
Of the group 5 elements, only vanadium plays a biological role. It is suspected to be an important trace element in human nutrition. It is a controversial dietary supplement for body-building, weight loss, and increasing insulin sensitivity. Rats and chickens require trace amounts of vanadium for growth and reproduction. It is essential in organisms that use vanabins in their blood or hemolymph. Vanadium-dependent enzymes are important in several types of marine algae.
With the exception of dubnium, which is dangerous because of its radioactivity, pure samples of the group 5 elements are not toxic. Some of their compounds are irritating. Niobium can be slightly toxic under certain conditions.
Group 5 Element Uses
Dubnium has no uses outside of research. The other three elements are important in metallurgy. Vanadium is used in vanadium steel for tools, armor, nuclear reactors, and springs. Vanadium oxide colors ceramics golden. Some vanadium compounds are important catalysts. Niobium is added to stainless steel. Its alloys exhibit high corrosion resistance. Tantalum increases heat and corrosion resistance of alloys. It is also used in surgical implants and electronics.
Sources
The primary sources of the lighter three group 5 elements are soil and sea water. Additionally, these elements occur in ores. Major vanadium ores are vanadinite, carnotite, and patronite. Niobium occurs in pyrochlore and columbite. Tantalum is found in pyrochlore and tantalite.
References
- Badmaev, V.; Prakash, Subbalakshmi; Majeed, Muhammed (1999). “Vanadium: a review of its potential role in the fight against diabetes”. The Journal of Alternative and Complementary Medicine. 5 (3): 273–291. doi:10.1089/acm.1999.5.273
- Cintas, Pedro (2004). “The Road to Chemical Names and Eponyms: Discovery, Priority, and Credit”. Angewandte Chemie International Edition. 43 (44): 5888–94. doi:10.1002/anie.200330074
- Emsley, John (2011). Nature’s Building Blocks: An A-Z Guide to the Elements (2nd ed.). Oxford University Press. ISBN: 978-0199605637.
- Greenwood, N. (2003). “Vanadium to dubnium: from confusion through clarity to complexity”. Catalysis Today. 78 (1–4): 5–11. doi:10.1016/S0920-5861(02)00318-8
- Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). Lehrbuch der Anorganischen Chemie (in German) (91–100 ed.). Walter de Gruyter. ISBN 3-11-007511-3.