Posts Tagged ‘Periodic Table

How the periodic table went from a sketch to an enduring masterpiece

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150 years ago, Mendeleev perceived the relationships of the chemical elements

In Danish physicist Niels Bohr’s 1922 version of the periodic table, adapted from a table by Danish chemist Julius Thomsen, elements with similar properties occupy horizontal rows connected by lines. The empty box on the right marks the expected occurrence of a group of elements that are chemically similar to the rare earth elements (numbers 58–70) in the preceding column.

Every field of science has its favorite anniversary.
For physics, it’s Newton’s Principia of 1687, the book that introduced the laws of motion and gravity. Biology celebrates Darwin’s On the Origin of Species (1859) along with his birthday (1809). Astronomy fans commemorate 1543, when Copernicus placed the sun at the center of the solar system.
And for chemistry, no cause for celebration surpasses the origin of the periodic table of the elements, created 150 years ago this March by the Russian chemist Dmitrii Ivanovich Mendeleev…

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January 13, 2019 at 1:07 pm

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The NEW Periodic Table Song (In Order)

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There’s Hydrogen and Helium Then Lithium, Beryllium Boron, Carbon everywhere Nitrogen all through the air

With Oxygen so you can breathe And Fluorine for your pretty teeth Neon to light up the signs Sodium for salty times

Magnesium, Aluminium, Silicon Phosphorus, then Sulfur, Chlorine and Argon Potassium, and Calcium so you’ll grow strong Scandium, Titanium, Vanadium and Chromium and Manganese

CHORUS This is the Periodic Table Noble gas is stable Halogens and Alkali react agressively Each period will see new outer shells While electrons are added moving to the right

Iron is the 26th Then Cobalt, Nickel coins you get Copper, Zinc and Gallium Germanium and Arsenic

Selenium and Bromine film While Krypton helps light up your room Rubidium and Strontium then Yttrium, Zirconium

Niobium, Molybdenum, Technetium Ruthenium, Rhodium, Palladium Silver-ware then Cadmium and Indium Tin-cans, Antimony then Tellurium and Iodine and Xenon and then Caesium and…

Barium is 56 and this is where the table splits Where Lanthanides have just begun Lanthanum, Cerium and Praseodymium

Neodymium’s next too Promethium, then 62’s Samarium, Europium, Gadolinium and Terbium Dysprosium, Holmium, Erbium, Thulium Ytterbium, Lutetium

Hafnium, Tantalum, Tungsten then we’re on to Rhenium, Osmium and Iridium Platinum, Gold to make you rich till you grow old Mercury to tell you when it’s really cold

Thallium and Lead then Bismuth for your tummy Polonium, Astatine would not be yummy Radon, Francium will last a little time Radium then Actinides at 89


Actinium, Thorium, Protactinium Uranium, Neptunium, Plutonium Americium, Curium, Berkelium Californium, Einsteinium, Fermium Mendelevium, Nobelium, Lawrencium Rutherfordium, Dubnium, Seaborgium Bohrium, Hassium then Meitnerium Darmstadtium, Roentgenium, Copernicium

Ununtrium, Flerovium Ununpentium, Livermorium Ununseptium, Ununoctium And then we’re done!!

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May 18, 2013 at 6:18 pm

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An early explanation of the periodic table

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Lars Vegard and X-ray spectroscopy

Scheme of energy levels of a heavy atom, with corresponding X‐ray emissions. Source: E. N. da Andrade, The Structure of the Atom, G. Bell and Sons, London, 1923

Helge Kragh
The Norwegian physicist Lars Vegard may have been the first to propose electron configurations for all the chemical elements, from hydrogen to uranium, on the basis of quantum atomic theory. This he did in papers of 1918-1919 in which he argued that the principal quantum number corresponded to the shells in Bohr’s picture of atomic structure. Vegard’s theory of the periodic system, based on the methods of theoretical X-ray spectroscopy in particular, was a significant advance but exerted little influence on the further development. It presupposed atoms made up of planar electron rings, and with the abandonment of the ring atom about 1920 this and similar models lost their credibility.

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December 19, 2011 at 4:50 pm

Chemistry and the Universe

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Chemistry, the study of the intricate dances and bondings of low-energy electrons to form the molecules that make up the world we live in, may seem far removed from the thermonuclear heat in the interiors of stars and the awesome power of supernovas. Yet, there is a fundamental connection between them.
To illustrate this connection, the familiar periodic table of elements—found in virtually every chemistry class—has been adapted to show how astronomers see the chemical Universe. What leaps out of this table is that the simplest elements, hydrogen and helium, are far and away the most abundant.

The Universe started out with baryonic matter in its simplest form, hydrogen. In just the first 20 minutes or so after the Big Bang, about 25% of the hydrogen was converted to helium. In essence, the chemical history of the Universe can be divided into two mainphases: one lasting 20 minutes, and the rest lasting for 13.7 billion years and counting.
After that initial one third of an hour, the expanding Universe cooled below the point where nuclear fusion could operate. This meant that no evolution of matter could occur again until stars were formed a few million years later. Then the buildup of elements heavier than helium could begin.
Stars evolve through a sequence of stages in which nuclear fusion reactions in their central regions build up helium and other elements (see illustration, above).The energy supplied by fusion reactions creates the pressure needed to hold the star up against gravity. Winds of gas escaping from stars distribute some of this processed matter into space in a relatively gentle manner and supernovas do it violently.

The chemical composition of the Universe has been constantly changing throughout its 13.7 billion year history.

As the enrichment of the interstellar and intergalactic gas has proceeded over vast stretches of space and time, the chemistry of the cosmos has become richer, too. Subsequent generations of stars have formed from interstellar gas enriched in heavy elements. Our Sun, Solar System, and indeed the existence of life on Earth are direct results of this long chain of stellar birth, death, and rebirth. In this way, the evolution of matter, stars and galaxies are all inextricably tied together and so too are astronomy and chemistry.
One of the principal scientific accomplishments of the Chandra X-ray Observatory has been to help unravel how the chemical enrichment by stellar winds and supernovas works on a galactic and intergalactic scale.
Chandra Images

Chandra images and spectra of individual supernova remnants reveal clouds of gas rich in elements such as oxygen, silicon, sulfur, calcium and iron, and track the speed at which these elements have been ejected in the explosion. The Chandra image of the Cas A supernova remnant shows iron rich ejecta outside silicon-rich ejecta, thus indicating that turbulent mixing and an aspherical explosion turned much of the original star inside out. Observations of Doppler-shifted emission lines for Cas A and other supernova remnants are providing three-dimensional information on the distribution and velocity of the supernova ejecta which will help to constrain models for the explosion.

On a larger scale, observations of galaxies undergoing bursts of star formation show that vast regions of these galaxies have been enriched by the combined action of thousands of supernovas. The Antennae galaxy system was produced by the collision of two galaxies. This collision created bursts of star formation and, few million years later, thousands of supernovas which heated and enriched clouds of gas thousands of light years in extent.

An unexpected agent for distributing heavy elements throughout a galaxy is a supermassive black hole in the center of a galaxy (for example, Sagittarius A*). Gas spiraling toward black holes can that become overheated and produce a wind of gas that flows away from the black hole, or it can create an intense electromagnetic field that drives enriched material into the outer reaches of the galaxy and beyond.

On a still larger scale, oxygen has been detected in intergalactic filaments millions of light years in length. This oxygen was likely produced more than ten billion years ago, in some of the first supernovas to occur in the history of the Universe. If the rate of supernovas gets so high that the combined effects of many supernova shock waves drives a galactic-scale wind that blows the gas out of the galaxy. A prime example is the galaxy M82.

Galactic winds such as the one in M82 are rare today, but they were common billions of years ago when galaxies were very young and stars were forming rapidly because of frequent collisions between galaxies. Chandra showed that the Sculptor Wall, a collection of gas and galaxies that stretches across tens of millions of light years, contains a vast reservoir of gas enriched in oxygen from galactic winds. The Sculptor Wall is thought to be part of an enormous web of hot, diffuse gas containing as much as half of all the ordinary matter in the Universe.

Periodic Table
In this version of the periodic table, the average relative abundance by mass of the various elements in the Universe is indicated by the number in the square, which gives the abundance in parts per 10,000. The sum of the abundances of all the elements without numbers is less than one part per 10,000. The abundances give important clues to the nuclear reactions and cosmic settings required to produce the various elements.

Click to launch the Flash piece

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June 9, 2011 at 9:42 pm

Periodic Table gets new elements (but no one knows what they do)

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They have existed for less than a second each, but two new elements have been added to the Periodic Table

Evidence for the existence of the two elements, the heaviest yet to be included, has been mounting for several years. A number of research teams had claimed to have produced the heavy elements by smashing together the nuclei of lighter atoms. But it took a three-year review before they received official status.
The teams behind the discoveries will be invited to suggest names for the new elements, and unless particularly outlandish requests are made, they are likely to be accepted. An announcement is expected soon.
In the meantime, the International Union of Pure and Applied Chemistry (IUPAC) has assigned the elements the names ununquadium and ununhexium, derivations from their atomic numbers of 114 and 116, respectively.
Also considered were claims for discoveries of elements with the atomic number 113, 115 and 118 – but the report of the Joint Working Party for the Discovery of New Elements, made up of representatives from the Union of Applied Chemistry and the Union of Applied Physics, dismissed the evidence for these as not strong enough.
Heavy elements tend to be radioactive, as their atoms have many more neutrons than protons and so decay quickly. There would seem to be no practical use for an element which is stable for less than a second before decay, but it moves research closer to developing elements with 120 or more protons. Nuclear theorists think these super-heavy atoms might remain in a stable condition for several decades and exhibit useful chemical properties.
“The discovery moves us closer to the island of stability,” said Dr Paul Karol, chairman of the joint working party. “Although 116 to 120 might seem like a small leap, it isn’t. But once we get there everything should get easier again. These elements should exist for longer, so we can observe their chemical properties. No one knows if they will remain stable for a few minutes or years. They may be able to power nuclear reactors, or be useful for nuclear weapons. No one’s sure – but you can always suspect the military will be interested.”
Scientists have been unable to ascertain much about the properties of the new elements. “The quantities produced were very small and did not exist for very long,” said Dr Karol. “Elements need to remain stable for almost a minute before much useful observation can be made of them.”
Plutonium, with an atomic number of 94, is the heaviest naturally occurring element. All the elements heavier than this, including Einsteinium, Rutherfordium and Californium, have been produced synthetically and decay rather rapidly.
Dr Terry Renner, the executive director of IUPAC, said: “If you got to 120 or 126 you might get something with an infinite half life. If that was the case you could possibly manufacture compounds from the new materials that might be useful in computer technology and medicine. But no one really knows, and it’s really all theoretical.”

Written by physicsgg

June 8, 2011 at 8:17 am