On the periodic table, most elements have at least one stable form. But others have only unstable forms, all of which decay by emitting radiation and transforming into different elements until becoming one that’s stable. The timescale of radioactive decay is known as an element’s half-life, the time it takes for a sample of an element to be reduced by half.
Generally for the elements...
The rare radioactive substance made its way from the United States to Russia on a commercial flight in June 2009. Customs officers balked at accepting the package, which was ensconced in lead shielding and emblazoned with bold-faced warnings and the ominous trefoil symbols for ionizing radiation. Back it went across the Atlantic.
U.S. scientists enclosed additional paper work and the...
Recognize these rows and columns? You may remember a detail or two about this mighty table’s organization from a long-ago chemistry class. Elements are ordered according to their number of protons, or atomic number. Metals are mostly to the left and nonmetals to the right. The column at the far right holds the noble gases, named for their general unwillingness to interact with other elements...
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...
It’s another raw day in St. Petersburg, Russia, but the man striding down the University Embankment along the Neva River isn’t pondering how the icy wind off the Gulf of Finland chills his bones or whether Emperor Alexander II’s reforms will increase salaries for professors like him. Instead, Dmitrii Mendeleev is imagining how he could reveal the chemical underpinnings of the universe...01/08/2019 - 07:15 History of Science, Chemistry