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The expression noble metal is sometimes confined to copper, silver, and gold since their full d-subshells can contribute to their noble character. [14] There are also known to be significant contributions from how readily there is overlap of the d-electron states with the orbitals of other elements, particularly for gold. [ 15 ]
Rhenium is a silvery-white metal with one of the highest melting points of all elements, exceeded by only tungsten. (At standard pressure carbon sublimes rather than melts, though its sublimation point is comparable to the melting points of tungsten and rhenium.)
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75 Re rhenium; use: 704 LNG: 704 WEL: 705 Zhang et al. 707 76 Os osmium; use: 678 LNG: 738 WEL: 630 Zhang et al. 678 77 Ir iridium; use: 564 LNG: 231.8 WEL: 560 Zhang et al. 564 78 Pt platinum; use: 510 LNG: 469 WEL: 490 Zhang et al. 510 79 Au gold; use: 342 CRC: 324 LNG: 324 WEL: 330 Zhang et al. 342 80 Hg mercury; use: 59.11 CRC: 59.11 LNG ...
The platinum-group metals [a] (PGMs) are six noble, precious metallic elements clustered together in the periodic table. 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.
Rhenium(VI) oxide has an appearance similar to that of copper. Rhenium(IV) oxide (or rhenium dioxide) is an oxide of rhenium, with the formula ReO 2. This gray to black crystalline solid is a laboratory reagent that can be used as a catalyst. It adopts the rutile structure. It forms via comproportionation: [4] 2 Re 2 O 7 + 3 Re → 7 ReO 2
Rhenium(VII) oxide can be formed when rhenium or its oxides or sulfides are oxidized a 500-700 °C in air. [24] It dissolves in water to give perrhenic acid. Heating Re 2 O 7 gives rhenium(IV) oxide, signalled by the appearance of the dark blue coloration. [25] In its solid form, Re 2 O 7 consists of alternating octahedral and tetrahedral Re ...
Refractory metals have high melting points, with tungsten and rhenium the highest of all elements, and the other's melting points only exceeded by osmium and iridium, and the sublimation of carbon. These high melting points define most of their applications. All the metals are body-centered cubic except rhenium which is hexagonal close-packed.