Dubnium - Db  105

A highly radioactive metal which does not occur naturally, and of which only a few atoms have ever been made. It is of research interest only.

Appearance unknown,  but probably metallic gray in appearance.

The element is named after the Russian town of Dubna.

• Atomic Number : 105
• Atomic Mass : 262.11
• Melting Point : N/A 
• Boiling Point : N/A
• Density : 29,000
• Ground State Electron Configuration : [Rn]5f¹⁴6d³7s²
• Shell: 2,8,18,32,32,11,2
• Orbital: 6d3

Discovery

Occurrence

A transuranium element created by bombarding ²⁴⁹Cf with ¹⁵N nuclei.

The first samples were made through nuclear reactions involving fusion of an isotope of californium, ²⁴⁹Cf, with one of nitrogen, ¹⁴N.
                                                                     ²⁴⁹Cf + ¹⁵N ® ²⁶⁰Db + 4n

A second route to the same isotope via berkelium is also known

                                                                                   ¹⁶N + ²⁴⁹Bk ²⁶¹Db + 4 n

Only very small amounts of of element 105, dubnium, have ever been made.  

Properties

Two separate groups have claimed to be the discoverers of the element, due to two differing isotopes. Credit has been shared between both. A synthetic element created via nuclear bombardment, few atoms have ever been made and the properties of dubnium are very poorly understood. It is a radioactive metal and is of research interest only. Interestingly, it is unlikely that any of the transuranium elements would ever be synthesised in large quantities due to the danger from their high radioactivity.