Search results
Results from the WOW.Com Content Network
Rhenium is a chemical element; it has symbol Re and atomic number 75. It is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one of the rarest elements in the Earth's crust. It has one of the highest melting and boiling points of ...
It is the raw material for all rhenium compounds, being the volatile fraction obtained upon roasting the host ore. [26] Rhenium, in addition to the +4 and +7 oxidation states, also forms a trioxide. It can be formed by reducing rhenium(VII) oxide with carbon monoxide at 200 C or elemental rhenium at 4000 C. [27] It can also be reduced with ...
Rhenium compounds are compounds formed by the transition metal rhenium (Re). Rhenium can form in many oxidation states , and compounds are known for every oxidation state from -3 to +7 except -2, although the oxidation states +7, +4, and +3 are the most common. [ 1 ]
The period 6 and 7 transition metals also add core (n − 2)f 14 electrons, which are omitted from the tables below. The p orbitals are almost never filled in free atoms (the one exception being lawrencium due to relativistic effects that become important at such high Z), but they can contribute to the chemical bonding in transition metal ...
The pnictogens exemplify the transition from nonmetal to metal going down the periodic table: a gaseous diatomic nonmetal (N), two elements displaying many allotropes of varying conductivities and structures (P and As), and then at least two elements that only form metallic structures in bulk (Sb and Bi; probably Mc as well).
Because of some analogy of elements 165–172 to periods 2 and 3, Fricke et al. considered them to form a ninth period of the periodic table, while the eighth period was taken by them to end at the noble metal element 164. This ninth period would be similar to the second and third period in having no transition metals. [16]
These elements are all transition metals in the d-block (groups 8, 9, and 10, periods 5 and 6). [1] The six platinum-group metals are ruthenium, rhodium, palladium, osmium, iridium, and platinum. They have similar physical and chemical properties, and tend to occur together in the same mineral deposits. [2]
Similar carbonyls are formed by technetium's congeners, manganese and rhenium. [24] Interest in organotechnetium compounds has also been motivated by applications in nuclear medicine . [ 20 ] Technetium also forms aquo-carbonyl complexes, one prominent complex being [Tc(CO) 3 (H 2 O) 3 ] + , which are unusual compared to other metal carbonyls.