Tuesday, March 17, 2020

Praseodymium Facts - Element 59

Praseodymium Facts - Element 59 Praseodymium is element 59 on the periodic table with the element symbol Pr. Its one of the rare earth metals or lanthanides. Here is a collection of interesting facts about praseodymium, including its history, properties, uses, and sources. Praseodymium was discovered by Swedish chemist Carl Mosander in 1841, but he did not purify it. He was working on rare earth samples, which contain elements with such similar properties they are extremely hard to separate from each other. From a crude cerium nitrate sample, he isolated an oxide he called lantana, which was lanthanum oxide. Lantana turned out to be a mixture of oxides. One fraction was a pink fraction he called didymium. Per Teodor Cleve (1874) and Lecoq de Boisbaudran (1879) determined didymium was a mixture of elements. In 1885, Austrian chemist Carl von Welsbach separated didymium into praseodymium and neodymium. Credit for the official discovery and isolation of element 59 is generally given to von Welsbach.Praseodymium gets it name from the Greek words prasios, which means green, and didymos, which means twin. The twin part refers to the element being the twin of neodymium in didymium, while green refers to the color of the salt isolated by von Welsbach. Praseody mium forms Pr(III) cations, which are yellowish green in water and glass. In addition to the 3 oxidation state, Pr also occurs in 2, 4, and (unique for a lanthanide) 5. Only the 3 state occurs in aqueous solutions.Praseodymium is a soft silver-colored metal that develops a green oxide coating in air. This coating peels or spalls off, exposing fresh metal to oxidation. To prevent degradation, pure praseodymium is typically stored under a protective atmosphere or in oil.Element 59 is highly malleable and ductile. Praseodymium is unusual in that it is paramagnetic at all temperatures above 1 K. Other rare earth metals are ferromagnetic or antiferromagnetic at low temperatures.Natural praseodymium consists of one stable isotope, praseodymium-141. 38 radioisotopes are known, the most stable being Pr-143, which has a half-life of 13.57 days. Praseodymium isotopes range from mass number 121 to 159. 15 nuclear isomers are also known.Praseodymium occurs naturally in the Earths crust at an abundance of 9.5 parts per million. It accounts for about 5% of the lanthanid es found in the minerals monazite and bastnasite. Seawater contains 1 part per trillion of Pr. Essentially no praseodymium is found in the Earths atmosphere. The rare earth elements have many uses in modern society and are considered extremely valuable. Pr gives a yellow color to glass and enamel. Around 5% of mischmetal consists of praseodymium. The element is used with other rare earths to make carbon arc lights. It colors cubic zirconia yellow-green and may be added to simulated gemstones to mimic peridot. Modern firesteel contains about 4% praseodymium. Didymium, which contains Pr, is used to make glass for protective eyewear for welders and glass blowers. Pr is alloyed with other metals to made powerful rare earth magnets, high strength metals, and magnetocaloric materials. Element 59 is used as a doping agent to make fiber optic amplifiers and to slow light pulses. Praseodymium oxide is an important oxidation catalyst.Praseodymium serves no known biological function. Like other rare earth elements, Pr exhibits low to moderate toxicity to organisms. Praseodymium Element Data Element Name: Praseodymium Element Symbol: Pr Atomic Number: 59 Element Group: f-block element, lanthanide or rare earth Element Period: period 6 Atomic Weight:  140.90766(2) Discovery: Carl Auer von Welsbach (1885) Electron Configuration: [Xe] 4f3  6s2 Melting Point:  1208  K  Ã¢â‚¬â€¹(935  Ã‚ °C, ​1715  Ã‚ °F) Boiling Point:  3403  K ​(3130  Ã‚ °C, ​5666  Ã‚ °F) Density:  6.77  g/cm3 (near room temperature) Phase: solid Heat of Fusion: 6.89 kJ/mol Heat of Vaporization:  331  kJ/mol Molar Heat Capacity:  27.20  J/(mol ·K) Magnetic Ordering: paramagnetic Oxidation States:  5, 4,  3, 2 Electronegativity:  Pauling  scale: 1.13 Ionization Energies: 1st:  527  kJ/mol2nd:  1020  kJ/mol3rd:  2086  kJ/mol Atomic Radius: 182 picometers Crystal Structure: double hexagonal close-packed or DHCP References Weast, Robert (1984).  CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp.  E110.Emsley, John (2011). Natures Building Blocks: An A-Z Guide to the Elements. Oxford University Press. ISBN 978-0-19-960563-7.Gschneidner, K.A., and Eyring, L., Handbook on the Physics and Chemistry of Rare Earths, North Holland Publishing Co., Amsterdam, 1978.Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.R. J. Callow,  The Industrial Chemistry of the Lanthanons, Yttrium, Thorium and Uranium, Pergamon Press, 1967.

Sunday, March 1, 2020

Brigadier General Nathaniel Lyon in the Civil War

Brigadier General Nathaniel Lyon in the Civil War Nathaniel Lyon - Early Life Career: The son of Amasa and Kezia Lyon, Nathaniel Lyon was born at Ashford, CT on July 14, 1818.   Though his parents were farmers, Lyon had little interest in pursuing a similar path.   Inspired by relatives who had served in the American Revolution, he instead sought a military career.   Gaining entry to West Point in 1837, Lyons classmates included John F. Reynolds, Don Carlos Buell, and Horatio G. Wright.   While at the academy, he proved an above average student and graduated in 1841 ranked 11th in a class of 52.   Commissioned as a second lieutenant, Lyon received orders to join the Company I, 2nd US Infantry and served with the unit during the Second Seminole War.   Nathaniel Lyon - Mexican-American War: Returning north, Lyon commenced garrison duty at Madison Barracks at Sacketts Harbor, NY.   Known as a tough disciplinarian with a fiery temper, he was court-martialed following an incident in which he beat a drunken private with the flat of his sword before hog-tying him and throwing him in jail.   Suspended from duty for five months, Lyons behavior led him to be arrested twice more prior to the beginning of the Mexican-American War in 1846.   Though he had concerns regarding the countrys motivation for war, he traveled south in 1847 as part of Major General Winfield Scotts army. Commanding a company in the 2nd Infantry, Lyon earned praise for his performance in the Battles of Contreras and Churubusco in August as well as received a brevet promotion to captain.   The following month, he sustained a minor leg wound in the final battle for Mexico City.   In recognition of his service, Lyon earned a promotion to first lieutenant.   With the end of the conflict, Lyon was sent to northern California to aid in maintaining order during the Gold Rush.   In 1850, he commanded an expedition sent to locate and punish members of the Pomo tribe for the deaths of two settlers.   During the mission, his men killed a large number of innocent Pomo in what became known as the Bloody Island Massacre. Nathaniel Lyon - Kansas: Ordered to Fort Riley, KS in 1854, Lyon, now a captain, was angered by the terms of the Kansas-Nebraska Act which permitted the settlers in each territory to vote to determine whether slavery would be permitted.   This resulted in a flood of pro- and anti-slavery elements into Kansas which in turn led to wide-ranging guerrilla warfare known as Bleeding Kansas.   Moving through the US Armys outposts in the territory, Lyon attempted to help keep the peace but steadily began supporting the Free State cause and the new Republican Party.   In 1860, he published a series of political essays in the Western Kansas Express which made his views clear.   As the secession crisis began following the election of Abraham Lincoln, Lyon received orders to take command of the St. Louis Arsenal on January 31, 1861. Nathaniel Lyon - Missouri: Arriving in St. Louis on February 7, Lyon entered a tense situation which saw the largely Republican city isolated in a mostly Democratic state.   Concerned about the actions of pro-secession Governor Claiborne F. Jackson, Lyon became allies with Republican Congressmen Francis P. Blair.   Assessing the political landscape, he advocated for decisive action against Jackson and enhanced the arsenals defenses.   Lyons options were hampered somewhat by Department of the West commander Brigadier General William Harney who favored a wait and see approach to dealing with the secessionists.   To combat the situation, Blair, through St. Louis Committee of Safety, commenced raising volunteer units comprised of German immigrants while also lobbying Washington for Harneys removal.         Though a tense neutrality existed through March, events accelerated in April following the Confederate attack on Fort Sumter.   When Jackson refused to raise the volunteer regiments requested by President Lincoln, Lyon and Blair, with permission from Secretary of War Simon Cameron, took it upon themselves to enlist the called for troops.   These volunteer regiments quickly filled and Lyon was elected their brigadier general.   In response, Jackson raised the state militia, part of which gathered outside the city at what became known as Camp Jackson.   Concerned about this action and alerted to a plan to smuggle Confederate weapons into the camp, Lyon scouted the area, and with the aid of Blair and Major John Schofield, devised a plan to surround the militia. Moving on May 10, Lyons forces succeeded in capturing the militia at Camp Jackson and began marching these prisoners to the St. Louis Arsenal.   En route, the Union troops were pelted with insults and debris.   At one point, a shot rang out which mortally wounded Captain Constantine Blandowski.   Following additional shots, part of Lyons command fired into the crowd killing 28 civilians.   Reaching the arsenal, the Union commander paroled the prisoners and ordered them to disperse.   Though his actions were applauded by those with Union sympathies, they led to Jackson passing a military bill which created the Missouri State Guard under the leadership of former governor Sterling Price.   Nathaniel Lyon - Battle of Wilson Creek: Promoted to brigadier general in the Union Army on May 17, Lyon assumed command of the Department of the West later that month.   A short time later, he and Blair met with Jackson and Price in an attempt to negotiate peace.   These efforts failed and Jackson and Price moved towards Jefferson City with the Missouri State Guard.   Unwilling to lose the state capital, Lyon moved up the Missouri River and occupied the city on June 13.   Moving against Prices troops, he won a victory at Booneville four days later and compelled the Confederates to retreat to the southwest.   After installing a pro-Union state government, Lyon added reinforcements to his command which he dubbed the Army of the West on July 2.   While Lyon encamped at Springfield on July 13, Prices command united with Confederate troops led by Brigadier General Benjamin McCulloch.   Moving north, this combined force intended to attack Springfield.   This plan soon came apart as Lyon departed the town on August 1. Advancing, he took the offensive with the goal of surprising the enemy.   An initial skirmish at Dug Springs the next day saw Union forces victorious, but Lyon learned that he was badly outnumbered.   Assessing the situation, Lyon made plans to retreat to Rolla, but first decided to mount a spoiling attack on McCulloch, who was encamped at Wilsons Creek, to delay the Confederate pursuit.   Attacking on August 10, the Battle of Wilson Creek initially saw Lyons command have success until its efforts were halted by the enemy.   As the fighting raged, the Union commander sustained two wounds but remained on the field.   Around 9:30 AM, Lyon was hit in the chest and killed while leading a charge forward.   Nearly overwhelmed, Union troops withdrew from the field later that morning.   Though a defeat, Lyons rapid actions in the preceding weeks helped keep Missouri in Union hands.   Left on the field in the confusion of the retreat, Lyons body was recovered by the Confederates and buried at a local farm.   Later recovered, his body was re-interred in his family plot in Eastford, CT where around 15,000 attended his funeral.   Ã‚   Selected Sources Civil War Trust: Nathaniel LyonState Historical Society of Missouri: Nathaniel LyonFirebrand in a Powder Keg