Group 5 of the periodic table consists of Vanadium, Niobium and Tantalum
They can be considered difficult transition metals and have a high melting point.
| Properties | V | Nb | Ta |
|---|---|---|---|
| Atomic Number | 23 | 41 | 73 |
| Electronic Configuration | [Ar] 3d3 4s2 | [Kr] 4d4 5s1 | [Xe] 4f14 5d3 6s2 |
| Metallic radius (nm) | 0.134 | 0.146 | 0.146 |
| M4+ radius (nm) | 0.056 | 0.070 | 0.073 |
| I1 (kJ mol-1) | 651 | 654 | 575 |
| Density (g cm-3) | 6.11 | 8.57 | 16.7 |
| Melting Point (K) | 2190 | 2740 | 3270 |
Ta and Nb have similar metallic radii because of lanthanide contraction; hence, their separation from a mixture is difficult. Their chemical reactivities are also very similar.
They are strong reducing agents.
The density of Ta is twice that of Nb.
The metallic bond strength increases from V to Ta, so the melting point also increases.
They are strong reducing agents but do not react with cold, dilute, non-oxidizing agents.
Oxidation States
These metals exhibit oxidation States from -I to +V, where +V is the most common oxidation state formed by all three metals.
| Oxidation States | V | Nb | Ta |
|---|---|---|---|
| -I | V(CO)6- | V(Nb)6- | V(Ta)6- |
| 0 | V(CO)6 | - | - |
| +I | V(dipy)3+ | (Π-C5H5)Nb(CO) 4 | (Π-C5H5)Ta(CO) 4 |
| +II | V(CN)64- | - | - |
| +III | V(NH3)63+ | NbCl3 | TaBr3 |
| +IV | K2VCl6 | NbCl4 | TaO2 |
| +V | VOCl3 | NbF5 | Na3TaF8 |
The +III and +IV oxidation states are also exhibited, but the lower oxidation states are uncommon and are stabilized by complex formation.
Halides
V forms one pentahalide, which is white coloured solid with the formula VF5.
It also forms vanadyl trihalides
The tetra halides can be formed by a direct combination of the elements.
Uses
Vanadium pentoxide is used as a catalyst in chemical industries.
The alloys of Nb are used for making jet engines.
Ta doesn’t corrode easily; hence, it makes reaction vessels in chemical industries. It is also used for making bone pins required in surgery.
