Ru identifies the chemical element ruthenium with atomic number 44. It is a rare transition metal from the platinum group of the periodic table. Ruthenium, like other platinum group metals, is inert to most other compounds. At Kazan State University, the element was discovered in 1844 by German-Baltic-born chemist Karl Ernst Claus and named it ruthenium in Russian. Ruthenium is usually a minor component of platinum ores; The annual production amount, which was 2009 tons in 19, increased to 2017 tons in 35,5. The majority of the ruthenium produced is used in thick film resistors and wear-resistant electrical connections. Ruthenium has a minor role in platinum alloys and as a catalyst in chemistry.
Covering layer for extreme ultraviolet photomasks is a new use for ruthenium. In the Ural Mountains, as well as in North and South America, ruthenium is typically found in ores with other platinum group metals. Pentlandite mined in Sudbury, Ontario, and pyroxenite deposits in South Africa both contain small but significant amounts of material.
Physical Properties of Ruthenium
Ruthenium's outermost shell contains only one electron (the last electron is in a subshell), unlike all other group 8 elements that have two electrons there. The nearby metals, niobium, molybdenum, and rhodium, also exhibit this anomaly.
Molecular Composition of Ruthenium
Ruthenium has four different crystal structures, it does not darken at normal settings, but oxidizes at 800 °C. When ruthenium dissolves in molten alkalis, ruthenates (RuO4-2 ) is produced. Halogens instead of acids (including aqua regia) attack it at high temperatures. In fact, oxidizing chemicals are the fastest attackers on ruthenium. Platinum and palladium can become harder when traces of ruthenium are added. The modest addition of ruthenium significantly improves the corrosion resistance of titanium. Both electroplating and thermal degradation can be used to coat the metal. A ruthenium-molybdenum alloy is known to be superconducting at temperatures lower than 10,6 K.
This is the first group from the left of the table where the second and third order transition metals show marked differences in chemical behavior. Ruthenium is the only 8d transition metal that can take the +4 group oxidation state, and even then it is less stable than the heavier osmium. Ruthenium, unlike osmium, can only produce aqueous cations in the +2 and +3 lower oxidation states, such as iron.
Since the 4d subshell is more than half full and electrons contribute less to metallic bonding, ruthenium is the first metal that tends to decrease in melting and boiling temperatures as well as in atomization enthalpy in 4d transition metals after the maximum seen in molybdenum.
Due to the half-filled [Kr]4d55s2 configuration, the previous element, technetium, has an abnormally low value out of the trend, but not out of the trend in the 3d series as manganese is in the 4d transition series. Ruthenium is paramagnetic at ambient temperature, unlike lighter congener iron, which is above the Curie point.
Isotopes of Ruthenium
Seven stable isotopes of ruthenium can be found in naturally occurring forms. 34 radioactive isotopes have also been identified. 373,59Ru with a half-life of 106 days, 39,26Ru with a half-life of 103 days, and 2,9Ru with a half-life of 97 days are the most stable of these radioisotopes.
Fifteen more radioisotopes with values ranging from 89.93 u (90Ru) to 114.928 u (115Ru) have been characterized. With the exception of 95Ru (half-life: 1.643 hours) and 105Ru (half-life: 4.44 hours), most of them have half-lives under five minutes.
Beta emission is the main form of decay after electron capture, which occurs before the most common isotope, 102Ru. Technetium is the main degradation product before 102Ru and rhodium is the next major degradation product.
A uranium or plutonium core splits to produce 106Ru. High levels of 106Ru discovered in the atmosphere have been associated with an allegation of an unreported nuclear accident in Russia in 2017.
Availability of Ruthenium
Ruthenium is a relatively rare element that makes up only 100 parts per trillion of the earth's crust and is the 78th most abundant element. In the Ural Mountains, as well as in North and South America, this element is typically found in ores with other platinum group metals. Both the pentlandite mined from Sudbury, Ontario, Canada, and the pyroxenite deposits in South Africa contain small but commercially significant amounts of the mineral. Ruthenium is an extremely rare mineral in its original form (Ir fills some of Ru's structural voids).
Given that the half-life of ruthenium's most stable radioisotope is "only" about a year, and nuclear fission produces a fairly large amount of ruthenium, suggestions are often made to recover ruthenium from spent fuel. The natural nuclear fission reactor operating at Oklo, Gabon, about two billion years ago, also contains an unusual ruthenium deposit. In fact, one of the many methods used in the geological past to detect when a nuclear fission chain reaction took place in that area was the ruthenium isotope ratio discovered there.
No more uranium is mined at Oklo, and no significant effort has been made to extract any of the platinum group metals found here.
Source: Wikipedia
Günceleme: 10/05/2023 21:10