Palladium

Palladium
General Info
Atomic Symbol	Atomic symbol::Pd
Atomic Number	Atomic number::46
Atomic Weight	Atomic weight::106.4 g/mol
Chemical series	Transition Metals
Appearance	Silvery White Metallic
Group, Period, Block	10, 5, D
Electron configuration	[Kr] 4d10
Electrons per shell	2, 8, 18, 18, 0
CAS number	CAS number::7440-05-3
Physical properties
Phase	Soild
Density	Density::12.023 g/ml
Melting point	Melting point::1554.9°C
Boiling point	Boiling point::2963°C
Isotopes of Palladium
iso NA half-life DT DE (MeV) DP 100Pd syn 3.63 d ε - 100Rh 100Pd syn 3.63 d γ 0.084, 0.074, 0.126 - 102Pd 1.02% 102Pd is stable with 56 neutrons. 103Pd syn 16.991 d ε - 103Rh 104Pd 11.14% 104Pd is stable with 58 neutrons. 105Pd 22.33% 105Pd is stable with 59 neutrons. 106Pd 27.33% 106Pd is stable with 60 neutrons. 107Pd syn 6.5x106 y β- 0.033 107Ag 108Pd 26.46% 108Pd is stable with 62 neutrons. 110Pd 11.72% 110Pd is stable with 64 neutrons.
All properties are for STP unless otherwise stated.

Palladium is a chemical element, which is part of the Chemical series also known as the transition metals. With an atomic number of 46, it remains in group 10, period 5, between elements rhodium and silver, and its element symbol is Pd. One of the most distinct properties of the transition elements is that they are “typical” metals. Many have high densities and considerable strength. They also have high luster and conform to desired shapes when pounded or stretched (Cox, p121). This is clearly shown by its silvery and white metallic appearance. Also it is very malleable and ductile, giving it a versatile use in many industries.

Properties

Surface of Palladium

Palladium, is a rare platinum metal, that has a silvery-white color. In addition it is very malleable and ductile. It also doesn’t tarnish in the air like many other elements. Its only set back is when sulfur comes in contact with moist air which then produces a slight amount of tarnish on it's surface.[1] Palladium displays chemical properties similar to other platinum group metals, but it is the least dense and it also has the lowest melting point. [2] Palladium’s strength and hardness come from its low temperature malleability or in other words its able to be worked cold, thus increasing it's strength. Palladium’s malleability is shown by its ability to be beaten into leaf as thin as 1/250,000 of an inch. It also exhibits the highest reactivity of all platinum group metals, which enables it to create compounds with most all elements. Palladium also has the ability of absorbing 900 times its own volume in hydrogen. [3] This makes palladium an essential catalyst in purifying hydrogen. [4]

Occurrences

Palladium Crystal

Palladium is present in the earth’s crust, but it’s very rare. According to many estimates there is a 1 to 10 ratio per trillion. [5] Palladium is found in two forms. Its first form is in its native form (not combined with any other metal). [6] Its second form is found as an alloy with many other platinum group metals such as gold and platinum. [7] It is commonly mined in placer deposits (an accumulation of valuable minerals formed by deposition of dense mineral phases in a trap site) in various locations. Many of these locations include the Ural Mountains, Australia, Ethiopia, South and North America. However when mined commercially, it is extracted from nickel-copper deposits in South Africa and Ontario. [8] This is a very lengthy process, but when the price of metal is just right, it becomes a profitable product. In addition the top two producers of Palladium are still Russia and South Africa, producing 93 percent of all palladium mined in the world. [9]

Uses

Cross section of a catalytic converter containing palladium.

Palladium has many uses in today’s society. These uses range from jewelry to catalytic converters. The automotive industry use the largest quantity of palladium out of all the other industries, for the production of catalytic converters. [10] A catalytic converter is a device used to burn up the excess fuel from a combustion engine thus reducing the toxicity of the fumes and providing a safer environment for all to live in. Palladium is also commonly used as a catalyst (any substance which increases or decreases a chemical reaction, while remaining the same). It is used in both hydrogenation and dehydrogenation reactions. [11] When palladium is heated it acts like a filter to purify hydrogen. [12] It has many sponge-like pores on its surface which enables it to absorb over 900 times its own volume in hydrogen. [13] It is also used to produce sulfuric acid which is commonly used in the fabric and paper industry. [14] Along with being used naturally, it is also combined with other metals to produce alloys. This is possible because of its extreme malleability. For instance white gold is a alloy of palladium and gold. This is possible because the palladium neutralizes the gold yellow color, thus producing a favorable white gold appearance. Palladium alloys are commonly used in the medical industry because of its favorable properties. Palladium continues to manifest itself as a versatile element that can be used in many industries.

History

Appearance of palladium

In the beginning of the 18th century, a chemist by the name of William Hyde Wollaston, discovered a new element, but was not officially announced until July 5, 1805. It was named after the discovery of the asteroid Pallas (which is also a Greek goddess of wisdom), which was discovered by Wilhelm Olbers in March 1802. The discovery sparked the interests, which eventually lead to the discovery of Palladium. During this time he had been working with precipitants of platinum salt, and since palladium is commonly accompanied with platinum it eventually led to its discovery. [15] During its beginning days it was commonly know as “The New Silver.” Wollaston first began by trying to sell it in Jacob Forster’s mineralogical shop. [16] This began to raise its popularity, and it began to appear on store shelves. As a direct result of this, it began to start controversies about its actuality. These controversies officially ended in 1805 when he wrote a scientific paper on its discovery, which he announced to all. [17] The discovery of this element has proved itself as a vital element in the development of scientific techniques.

References

• Cox, Heather E., et al. Chemistry for Christian Schools - Second Edition. Bob Jones University Press. 2000.
• Palladium Bentor, Yinon, Dec. 5, 2009.
• Palladium www.Chemistryexplained.com .
• Palladium www.Radiochemistry.com .
• Palladium Essential Information WebElements Periodic Table of the Elements
• Palladium element Facts www.chemicool.com
• Palladium Catalyst Pacific Northwest National Laboratory
• Palladium Occurrences www.experiencefestival.com
• Palladium History www.vanderkrogt.net