Search: Periodic Table
The positions of the elements La, Ac, Lu, and Lr in the WebElements periodic table is justified eloquently in the article by William B. Jensen.1 in J. Chem. Ed..
Elements 117 is not known at the time of writing, but are shown "greyed-out" in the tables at their expected positions for information.
- 1. The positions of lanthanum (actinium) and lutetium (lawrencium) in the periodic table,
, Journal of Chemical Education, 08/1982, Volume 59, Issue 8, p.634-636, (1982)
Periods in the periodic table
There are 7 periods in the standard form of the periodic table:
- Period 1
- Period 2
- Period 3
- Period 4
- Period 5
- Period 6
- Period 7
In the standard form of the periodic table the s-block, p-block, and d-block elements are organised into horizontal rows called periods. In WebElements these are labelled from 1 to 7.
The f-block elements are assigned to Periods 6 (lanthanoids) and 7 (actinoids) since that is where they are located in the full, or extended, version of the periodic table.
<a href="http://www.webelements.com/"> <img border="0" height="31" width="88" src="http://www.webelements.com/webelements/support/media/icon/webelements-button.gif" alt="Start WebElements"></a>
In honour of scientist and astronomer Nicolaus Copernicus (1473-1543), the discovering team around Professor Sigurd Hofmann suggested the name copernicium with the element symbol Cp for the new element 112, discovered at the GSI Helmholtzzentrum für Schwerionenforschung (Center for Heavy Ion Research) in Darmstadt. It was Copernicus who discovered that the Earth orbits the Sun, thus paving the way for our modern view of the world. Thirteen years ago, element 112 was discovered by an international team of scientists at the GSI accelerator facility. A few weeks ago, the International Union of Pure and Applied Chemistry, IUPAC, officially confirmed their discovery. In around six months, IUPAC will officially endorse the new element's name. This period is set to allow the scientific community to discuss the suggested name copernicium before the IUPAC naming.
"After IUPAC officially recognized our discovery, we – that is all scientists involved in the discovery – agreed on proposing the name copernicium for the new element 112. We would like to honor an outstanding scientist, who changed our view of the world", says Sigurd Hofmann, head of the discovering team.
Copernicus was born 1473 in Torun; he died 1543 in Frombork, Poland. Working in the field of astronomy, he realized that the planets circle the Sun. His discovery refuted the then accepted belief that the Earth was the center of the universe. His finding was pivotal for the discovery of the gravitational force, which is responsible for the motion of the planets. It also led to the conclusion that the stars are incredibly far away and the universe inconceivably large, as the size and position of the stars does not change even though the Earth is moving. Furthermore, the new world view inspired by Copernicus had an impact on the human self-concept in theology and philosophy: humankind could no longer be seen as the center of the world.
With its planets revolving around the Sun on different orbits, the solar system is also a model for other physical systems. The structure of an atom is like a microcosm: its electrons orbit the atomic nucleus like the planets orbit the Sun. Exactly 112 electrons circle the atomic nucleus in an atom of the new element "copernicium".
Element 112 is the heaviest element in the periodic table, 277 times heavier than hydrogen. It is produced by a nuclear fusion, when bombarding zinc ions onto a lead target. As the element already decays after a split second, its existence can only be proved with the help of extremely fast and sensitive analysis methods. Twenty-one scientists from Germany, Finland, Russia and Slovakia have been involved in the experiments that led to the discovery of element 112.
Since 1981, GSI accelerator experiments have yielded the discovery of six chemical elements, which carry the atomic numbers 107 to 112. The discovering teams at GSI already named five of them: element 107 is called bohrium, element 108 hassium, element 109 meitnerium, element 110 darmstadtium, and element 111 is named roentgenium.
The new element 112 discovered by GSI has been officially recognized and will be named by the Darmstadt group in due course. Their suggestion should be made public over this summer.
The element 112, discovered at the GSI Helmholtzzentrum für Schwerionenforschung (Centre for Heavy Ion Research) in Darmstadt, has been officially recognized as a new element by the International Union of Pure and Applied Chemistry (IUPAC). IUPAC confirmed the recognition of element 112 in an official letter to the head of the discovering team, Professor Sigurd Hofmann. The letter furthermore asks the discoverers to propose a name for the new element. Their suggestion will be submitted within the next weeks. In about 6 months, after the proposed name has been thoroughly assessed by IUPAC, the element will receive its official name. The new element is approximately 277 times heavier than hydrogen, making it the heaviest element in the periodic table.
“We are delighted that now the sixth element – and thus all of the elements discovered at GSI during the past 30 years – has been officially recognized. During the next few weeks, the scientists of the discovering team will deliberate on a name for the new element”, says Sigurd Hofmann. 21 scientists from Germany, Finland, Russia and Slovakia were involved in the experiments around the discovery of the new element 112.
Since 1981, GSI accelerator experiments have yielded the discovery of six chemical elements, which carry the atomic numbers 107 to 112. GSI has already named their officially recognized elements 107 to 111: element 107 is called Bohrium, element 108 Hassium, element 109 Meitnerium, element 110 Darmstadtium, and element 111 is named Roentgenium.
It is suggested that poisoning by polonium-210 may have caused the death of Alexander Litvinenko, said to be a former Russian spy, in November 2006. Following his death at the end of November 2006, traces of polonium were found at several places he had visited before becoming ill. Before his death it was thought that thallium, or even radiothallium, might have been the cause of his illness. At the time of writing it is not clear who killed him, but not surprisingly the Russians deny it. Polonium-210 decays through the emission of α-particles and these emissions are noramlly easy to stop, but they are very dangerous if the polonium is inside the body.
Polonium is radioactive and present only in extremely low abundances in the environment. It is quite metallic in nature despite its location beneath oxygen in the periodic table. It is made in very small quantities through a nuclear reaction of bismuth. Neutron irradiation of 209bismuth (atomic number 83) gives 210polonium (atomic number 84).
209Bi + 1n → 210Po + e-
Polonium-210, 210Po, transmutes into the lead isotope 206Pb by the emission of an α-particle. The half life for this process is just over 138 days meaning that after 138 days one-half of the original 210Po has disappeared and after 2 times 138 days 3/4 has gone.
21084Po → 20682Pb + 42He
The short half life of polonium-210 and the heat generated with the above radioactive decay means that polonium metal generates considerable heat (141 W), meaning that the metal and its compounds self-heat. This is a useful property and polonium can be used as a small heat source (if expensive!). It can be used in space satellites for this purpose and is especially desirable as there are no moving parts. It was also used in the lunar rovers to keep internal parts warm during the frigid lunar nights.
Polonium metal is unique in that it is the only element whose structure (known as the α-form) is a simple cubic array of atoms in which each atom is surrounded by six other polonium atoms. On gentle warming to 36°C, this converts into a second form known as the β-form.
Polonium dissolves in acids to form pink hydrated Po(II), presumably as[Po(OH2)6]2+. This seems to oxidize to yellow Po(IV) species perhaps as a consequence of oxidizing agents produced through the α-particle induced decay of water. The polonium(II) oxide PoO is known but this oxidizes easily to the Po(IV) oxide PoO2.
There are few crystallographically characterised polonium compounds largely because not many researchers work with polonium and the difficulties associated with characterising such radioactive compounds. The 14-electron polonium(IV) anion [PoI6]2– is strictly octahedral meaning the lone pair is sterochemically inactive.
The 2006 Ig Noble prize for chemistry has been announced and was awarded to Spanish researchers Antonio Mulet, José Javier Benedito and José Bon (University of Valencia), and Carmen Rosselló (University of Illes Balears), for their outstanding research: "Ultrasonic Velocity in Cheddar Cheese as Affected by Temperature." published in the Journal of Food Science.1
The Ig Noble prizes are administered by the publishers of the Annals of Improbable Research magazine. It's not always clear to me that the Chemistry Ig Noble prizes seem more related to other areas, and some non-chemistry prizes look as though the work was chemical, but never mind. For the record, here are a few of the more recent awards.
Edward Cussler and Brian Gettelfinger (University of Minnesota and the University of Wisconsin), for their work that finally settled the longstanding scientific question: can people swim faster in syrup or in water? See "Will Humans Swim Faster or Slower in Syrup?".2
The Coca-Cola Company of Great Britain, for using advanced technology to convert ordinary tap water into Dasani, a transparent form of water, which for "precautionary reasons" was withdrawn form the market in the UK (it seems the Dasani contained the carcinogenic bromate - the UK Food Standards Agency advice was that while Dasani contained illegal levels of bromate, it did not present an immediate risk to the public). See various press stories including:
Yukio Hirose of Kanazawa University in Japan, for his chemical investigation of a bronze statue in the city of Kanazawa that fails to attract pigeons.
Theodore Gray of Wolfram Research (Champaign, Illinois, USA) for gathering elements of the periodic table and assembling them into a periodic table table.
- 1. Ultrasonic Velocity in Cheddar Cheese as Affected by Temperature,
, Journal of Food Science, 11/1999, Volume 64, Issue 6, p.1038 - 1041, (1999)
- 2. Will humans swim faster or slower in syrup?,
, AIChE Journal, 11/2004, Volume 50, Issue 11, p.2646 - 2647, (2004)
China is expecting to complete work on the Heavy Ion Research Facility in Lanzhou (HIRFL) - Cooler Storage Ring (CSR) soon. Its director, Zhan Wenlong, of the Chinese Academy of Sciences, said "our target is to form new heavy elements and expand the Periodic Table" and "the building of large science facilities demonstrates not only our specific technological know-how, but also the prowess of our basic research".
The HIRFL-CSR, with a state investment of about 300 million yuan (37.5 U.S. dollars), includes a main ring, experimental ring, a radioactive separator and experimental detectors. "The building of large science facilities demonstrates not only our specific technological know-how, but also the prowess of our basic research," Zhan said. Chinese science strategists decided to build the HIRFL in the mid 1980s. The facility, which was put into operation in December 1988, was awarded the top national prize for technological advancement in 1992.
The CSR is the latest upgrade of the HIRFL, which has helped Chinese scientists to form two new heavy-nuclear elements.
I've taken the liberty of reproducing a CHMED-L post from Eric Scerri about hydrogen's position in the periodic table.
The position of hydrogen in the periodic system is a much debated topic. Authors have suggested groups I, VII and even IV over the years. Others opt from removing H from the main body of the table, along with He. The official journal of IUPAC, called Chemistry International, has been running some articles and comments on this issue.