Mendeleev’s periodic table, published in 1869, was a vertical chart that organized 63 known elements by atomic weight. This arrangement placed elements with similar properties into horizontal rows.

At the American Chemical Society (ACS), our vision is to improve people's lives through the transforming power of chemistry. Next year marks the 150th anniversary of the publication of Mendeleev's ...

The periodic table brought solidity to a field of inquiry that had long been squishy. Sir Isaac Newton, in Query 31, a section in his 1717 work “Opticks,” listed and ranked chemical compounds ...

An international team of scientists has shed light on the extreme ends of neutron and proton numbers. Their goal is to investigate the limits of the periodic table of chemical elements. How far ...

Elements 113, 115, 117 and 118 to be named by scientists from Russia, the United States and Japan.

Discover the history, structure, and importance of the periodic table of elements, from Mendeleev’s discovery to modern scientific applications. When you purchase through links on our site, we ...

All matter–oceans, land, atmosphere, humans, animals, plants, food, materials, products, buildings–is made from 118 known chemical elements. These elements are ordered in the periodic table of ...

Today, the periodic table is organized by atomic number, which is the number of protons in the nucleus. But they didn’t know about protons then, so they organized everything by atomic weight.

It can be possible to predict whether an atom will form a cation or an anion based on its position on the periodic table. Halogens always form anions, alkali metals and alkaline earth metals always ...

The modern version of this chemical element chart has been tweaked to account for the quantum theory that governs the arrangement of electrons surrounding the nucleus and the outermost electrons that ...

The periodic table of chemical elements, often called the periodic table, organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic ...