Isotopes

Naturally-occurring palladium is composed of six isotopes. The most stable radioisotopes are ¹⁰⁷Pd with a half-life of 6.5 million years, ¹⁰³Pd with a half-life of 17 days, and ¹⁰⁰Pd with a half-life of 3.63 days. Eighteen other radioisotopes have been characterized with atomic weights ranging from 92.936 u (⁹³Pd) to 119.924 u (¹²⁰Pd). Most of these have half-lives that are less than a half-hour, except ¹⁰¹Pd (half-life: 8.47 hours), ¹⁰⁹Pd (half-life: 13.7 hours), and ¹¹²Pd (half-life: 21 hours).

The primary decay mode before the most abundant stable isotope, ¹⁰⁶Pd, is electron capture and the primary mode after is beta decay. The primary decay product before ¹⁰⁶Pd is rhodium and the primary product after is silver.

Radiogenic ¹⁰⁷Ag is a decay product of ¹⁰⁷Pd and was first discovered in the Santa Clara, California meteorite of 1978.^[13] The discoverers suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. ¹⁰⁷Pd versus Ag correlations observed in bodies, which have clearly been melted since accretion of the solar system, must reflect the presence of short-lived nuclides in the early solar system

Characteristics

Palladium belongs to group 10 in the periodic table:

Z	Element	No. of electrons/shell
28	nickel	2, 8, 16, 2
46	palladium	2, 8, 18, 18
78	platinum	2, 8, 18, 32, 17, 1
110	darmstadtium	2, 8, 18, 32, 32, 17, 1

but has a very atypical configuration in its outermost electron shells compared to the rest of the members of group 10, if not to all elements. (See also niobium (41), ruthenium (44), and rhodium (45).)

Palladium is a soft silver-white metal that resembles platinum. It is the least dense and has the lowest melting point of the platinum group metals. It is soft and ductile when annealed and greatly increases its strength and hardness when it is cold-worked. Palladium dissolves slowly in sulfuric, nitric, and hydrochloric acid.^[5] This metal also does not react with oxygen at normal temperatures (and thus does not tarnish in air). Palladium heated to 800°C will produce a layer of palladium(II) oxide (PdO). It lightly tarnishes in moist atmosphere containing sulfur.

The metal has the uncommon ability to absorb up to 900 times its own volume of hydrogen at room temperatures. It is thought that this possibly forms palladium hydride (PdH₂) but it is not yet clear if this is a true chemical compound.^[5] When palladium has absorbed large amounts of hydrogen, it will expand slightly in size.^[12]

Common oxidation states of palladium are 0,+1, +2 and +4. Although originally +3 was thought of as one of the fundamental oxidation states of palladium, there is no evidence for palladium occurring in the +3 oxidation state; this has been investigated via X-ray diffraction for a number of compounds, indicating a dimer of palladium(II) and palladium(IV) instead. Recently, compounds with an oxidation state of +6 were synthesised.

Occurrence

In 2005, Russia was the top producer of palladium, with at least 50% world share, followed by South Africa, Canada and the U.S., reports the British Geological Survey.

Palladium may be found as a free metal alloyed with gold and other platinum group metals in placer deposits of the Ural Mountains, Australia, Ethiopia, South and North America. It is commercially produced from nickel-copper deposits found in South Africa, Ontario, and Siberia; It takes processing of many metric tons of ore to extract just one troy ounce of palladium. However, the mine production could still be profitable, depending on current metal prices, as other metals are produced together: nickel, copper, platinum and rhodium.

The world's largest single producer of palladium is MMC Norilsk Nickel produced from the Norilsk–Talnakh nickel deposits. The Merensky Reef of the Bushveld Igneous Complex of South Africa contains significant palladium in addition to other platinum group elements. The Stillwater igneous complex of Montana and the Roby zone orebody of the Lac des Îles igneous complex of Ontario also contain mineable palladium.

Palladium is also produced in nuclear fission reactors and can be extracted from spent nuclear fuel, see Synthesis of noble metals, though the quantity produced is insignificant.

History

Palladium was discovered by William Hyde Wollaston in 1803.^[3][4] This element was named by Wollaston in 1804 after the asteroid Pallas, which had been discovered two years earlier.^[5] Wollaston found palladium in crude platinum ore from South America by dissolving the ore in aqua regia, neutralizing the solution with sodium hydroxide, and precipitating platinum as ammonium chloroplatinate with ammonium chloride. He added mercuric cyanide to form the compound palladium cyanide, which was heated to extract palladium metal.

Palladium chloride was at one time prescribed as a tuberculosis treatment at the rate of 0.065g per day (approximately one milligram per kilogram of body weight). This treatment did have many negative side-effects, and was later replaced by more effective drugs.^[6]

Palladium's affinity for hydrogen led it to play an essential role in the Fleischmann-Pons experiment in 1989, also known as cold fusion.

In the run up to 2000, Russian supply of palladium to the global market was repeatedly delayed and disrupted^[7] because the export quota was not granted on time, for political reasons. The ensuing market panic drove the palladium price to an all-time high of $1100 per ounce in January 2001.^[8] Around this time, the Ford Motor Company, fearing auto vehicle production disruption due to a possible palladium shortage, stockpiled large amounts of the metal purchased near the price high. When prices fell in early 2001, Ford lost nearly US$1 billion.^[9] World demand for palladium increased from 100 tons in 1990 to nearly 300 tons in 2000. The global production of palladium from mines was 222 metric tons in 2006 according to USGS data.^[10] Most palladium is used for catalytic converters in the automobile industry

Palladium

Palladium (pronounced /pəˈleɪdiəm/) is a chemical element with the chemical symbol Pd and an atomic number of 46. Palladium is a rare and lustrous silvery-white metal that was discovered in 1803 by William Hyde Wollaston, who named it after the asteroid Pallas, which in turn, was named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas.

Palladium, along with platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). Platinum group metals share similar chemical properties, but palladium has the lowest melting point and is the least dense of these precious metals.^[1]

The unique properties of palladium and other platinum group metals account for their widespread use. One in four goods manufactured today either contain platinum group metals or had platinum group metals play a key role during their manufacturing process^[2]. Over half of the supply of palladium and its sister metal platinum goes into catalytic converters, which convert up to 90% of harmful gases from auto exhaust (hydrocarbons, carbon monoxide and nitrogen oxide) into less harmful substances (nitrogen, carbon dioxide and water vapor). Palladium’s precious metal qualities and appearance generate significant consumption in the luxury jewelry market. Palladium is found in many electronics including computers, mobile phones, multi-layer ceramic capacitors, component plating, low voltage electrical contacts, and SED/OLED/LCD televisions. Palladium is also used in dentistry, medicine, hydrogen purification, chemical applications, and groundwater treatment. Palladium plays a key role in the technology used for fuel cells, which combines hydrogen and oxygen to produce electricity, heat and water.

Anthony Dimond

Anthony Joseph Dimond (November 30, 1881 – May 28, 1953) was an American Democratic Party politician who was the Alaska Territory Delegate in the United States House of Representatives for many years (1933-1945). Dimond was also an early champion of Alaska statehood.

Dimond was born in New York and attended Catholic schools, taught school in Montgomery County, New York (1900-1903) and was a prospector/miner in Alaska (1904-1912) before studying law and beginning practice in Valdez (1913).

Dimond's political experience includes: US Commissioner in Chisana, Alaska (1913-1914); Special Assistant US Attorney for the 3rd Judicial Division of Alaska in Valdez (1917); Mayor of Valdez (1920-1922, 1925-1932); Alaska Territorial Senate (1923–1926, 1929–1932); and District Judge for the 3rd Division of Alaska (1945–1953). He also served as a Delegate to the Democratic National Convention in 1936 and 1940. He died on May 28, 1953 in Anchorage.

A Roman Catholic, Dimond was a member of organizations such as the Elks, Moose and Eagles. His secretary, Bob Bartlett, eventually became a United States Senator from Alaska.

Today, November 30 is celebrated by the State of Alaska as "Anthony Dimond Day." In Anchorage, A. J. Dimond High School and Dimond Blvd, a major thoroughfare, are named after him.

In 1940, when President Franklin D. Roosevelt was considering making Alaska an international Jewish homeland, Dimond was the main force behind defeating the effort. Some Alaskan papers have attributed this to anti-Semitism on the part of Dimond and others, although the charge was challenged by historians who claimed that Dimond was mostly concerned about the finances

History

Elmhurst began in 1865, when a railroad station was constructed by the San Francisco and Oakland Railroad.^[1] Originally named "Jones", the station was renamed "Elmhurst" in 1869.^[1] The town's first post office was established in 1892.^[1] The town of Elmhurst was primarily an agricultural community. After the 1906 San Francisco Earthquake, East Bay communities grew in population, and the City of Oakland annexed several surrounding communities in 1909, including Elmhurst. The neighborhood grew into a manufacturing center in the years that followed, with automobile manufacturing playing a significant role.^[2] Chevrolet opened an auto assembly plant in Elmhurst in 1915, which shut down in the 1950s.

Elmhurst was the site of one of the large carbarns for the Key System's streetcars, the Elmhurst Carhouse.

Although it was historically a white working-class neighborhood, it became predominantly African American after World War II, and today, Latinos now form about half of Elmhurst's population.