Manganese group
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Position in the periodic table
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| group | 7th |
| period | |
| 4th |
25 mn |
| 5 |
43 Tc |
| 6th |
75 Re |
| 7th |
107 hours |
The 7th group of the periodic table contains the elements manganese , technetium , rhenium and the element 107 boringium , which was first produced in 1977 . The group is also called the manganese group after its first member .
The metals of the group have similar chemical properties in the form of the oxidation states +2, +3, +4, +6 and +7, whereby rhenium and technetium are more similar. This is due to the almost identical atomic and ionic radii of rhenium and technetium due to the lanthanide contraction . Manganese shows the most stable compounds in the levels +2, +4 and +7, while the higher homologues tend to prefer the levels +3, +4 and +7.
At around 0.1%, manganese is a transition metal that occurs frequently in the earth's shell . Technetium was the first man-made element. The rare (0.7 ppb in the earth's crust) rhenium has the second highest boiling point of all metals at 5869 K (5596 ° C) after tungsten 6203 K (5930 ° C).
Manganese and rhenium are of technical importance as components of alloys, predominantly with iron , and in compounds as catalysts . Manganese in metalloenzymes is also involved in catalytic processes in organisms .
| Properties of the manganese group metals | ||||
| Surname | manganese | Technetium | rhenium | Bohrium |
| Melting point | 1517 K (1244 ° C) | 2430 K (2157 ° C) | 3459 K (3186 ° C) | ? |
| boiling point | 2235 K (1962 ° C) | 5150 K (4877 ° C) | 5869 K (5596 ° C) | ? |
| density | 7.47 g cm −3 | 11.5 g cm −3 | 19.25 g cm −3 | ? |
| Appearance | silvery metallic | silver gray metallic | shiny white metallic |
? |
| Atomic radius | 140 pm | 135 pm | 135 pm | ? |
- The metals
Manganese, electrolyte chips, 99.99%
Rhenium, single crystal 99.999%, bar, 99.995%
Individual evidence
literature
- AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , pp. 1607-1634.