|of the titles of this article is ambiguous. For further meanings see palladium (term clarifying).|
|name, symbol, ordinal number||palladium, Pd, 46|
|series||of transition metals|
|group, period, block||10, 5, D|
|appearance||silvery, knows, metallically|
|proportion at the Earth's shell||1 · 10 -6 %|
|Atomic radius (computed)||140 (169) pm|
|Kovalenter radius||131 pm|
|van the Waals radius||163 pm|
|Elektronenkonfiguration||[Kr] 4d 10 5s 0|
|electrons per energy level||2, 8, 18, 18, 0|
|1. Ionization energy||804.4 kJ/mol|
|2. Ionization energy||1870 kJ/mol|
|3. Ionization energy||3177 kJ/mol|
|state of aggregation||firmly|
|crystal structure||cubically face-centered|
|density (Mohshärte)||12023 kg/m 3 (4,75)|
|melting point||1828.05 K (1554.90 °C)|
|boiling point||3236 K (3125 °C)|
|molecular volume||8,56 · 10 -6 m 3 /mol|
|heat of vaporization||357 kJ/mol|
|heat of fusion||17.6 kJ/mol|
|steam pressure||1.33 Pa at 1825 K|
|speed of sound||3070 m/s with 293,15 K|
|specific thermal capacity||244 j (kg · K)|
|Electrical conductivity||9,5 · 10 6 S /m|
|heat conductivity||71.8 w (m · K)|
|oxidation conditions||0, +2, +4|
|oxides (basicity)||PdO (easily basic)|
|Elektronegativität||2.20 (Pauling scale)|
|Normalpotenzial||0.915 V (Pd 2+ + 2e - → Pd)|
| as far as possible and common, is used SI-UNITs.|
If not differentlynoted,
the indicated data apply with standard conditions.
Palladium is a chemical element in the periodic system of the elements with the symbol Pd and the ordinal number 46. The rare silver-white transition metal of group of platinum resembles very platinum in the chemical behavior.
Table of contents
palladium was discovered 1803 by William Hyde Wollaston. It designated it two years before 1804 after that discovered Asteroiden Pallas. Wollaston found the element 46in South American platinum ore due to to small yields samples dissolved at platinum out in aquae regiae.
With the old car disposal the portion of the rezyklierten palladium from the waste gas catalysts will rise. Over the possibilityto the production of palladium from burned down fuel elements, see precious metal synthesis.
a metal and the lightest element of group of platinum are pure. Therefore it has the lowest melting point from the elements of this group and is also most reaction-joyfully. At ambient temperature it does not react however with oxygen. It keeps its metallic gloss at air and does not start not. In the glowed condition it is soft and duktil, during deformation at low temperatures rises the firmness and hardness howeverfast on (cold working).
Palladium is a precious metal, even if it is clearly more reactive than relatives the element platinum: It separates in nitric acid. In hydrochloric acid it dissolves with Luftzutritt slowly. The precious metal character from palladium is thatthe neighbouring silver comparably: In many acids palladium is the nobler metal, in hydrochloric acid behaves it however due to the formation of easy-soluble palladium chloride connections more unedler.
Palladium possesses the highest absorption capacity of all elements for hydrogen. At ambient temperature it can do that900-fache, Palladiummohr the 1200-fache and colloidal palladium solutions the 3000-fache of the own volume bind. One can describe the absorption of hydrogen as release from hydrogen in the metal lattice and as formation palladium of a hydride with the approximate composition Pd 2 H. With 30 °Cand normal print corresponds the maximum hydrogen palladium relationship to the formula PdH 0.608.
Usually it accepts the Oxidationsstufen +2 and +4. With connections of the apparent Oxidationsstufe +3 it concerns Pd (II) /Pd (IV) - alloys. In newer investigations also hexavalent palladium could be represented.
finely divided is palladium a exzellenter catalyst for the acceleration of chemical reactions, in particular hydrogenations and dehydrogenations (installation and withdrawal of hydrogen), as well as to the Cracken of hydrocarbons.
- Waste gas catalysts for petrol engines. (Palladium displaces the more expensive Platinum.)
- decoration goods (particularly in China)
- weissgold (palladium “decolorizes” gold)
- platinum crucible (80% Pt, 20% Pd)
- purifying foils. Similar to the gold foil palladium can be rolled out to 0.00001 mm of thin foils.
- Cleaning of hydrogen. In hot palladium hydrogen possesses inhigh Diffusionsvermögen.
- Contact materials for interphones
- of tooth implants
- medical instruments
- of electrode materials for spark plugs (aviation)
- Pd/Ni alloys as replacement for gold in the electrical industry
- nano-technology (over e.g. serves as catalyst. to manufacture molecular connections)
Web on the left of
- Los Alamos national Laboratory - palladium
- WebElements.com - palladium
- EnvironmentalChemistry.com - palladium
- Charts: Trend of prices palladium in dollar
- palladium coins/palladium coins
|Wiktionary: Palladium - word origin, synonyms and translations|
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