Students use the terms isotope, atomic number, mass number, and atomic mass. Atomic Theory: Structure of the Atom: Students use the terms isotope, atomic number, mass number, and atomic mass to ...

Nineteen elements on the periodic table — including gold, cadmium, arsenic and aluminum — are getting their atomic weights adjusted. The International Union of Pure and Applied Chemistry (IUPAC) ...

Ten elements that help make up the universe, including the carbon our biology is based on and the oxygen in the air we breathe, are now getting changed in an unprecedented way — they are getting their ...

In a letter to the editor published in the Dec. 4, 1913, issue of Nature, English radiochemist Frederick Soddy proposed the isotope concept—that elements could have more than one atomic weight. The ...

This year we celebrate the 150 th anniversary of Mendeleev’s achievement in formulating the structure of the periodic table that we use today. He announced his structure in 1869, but the challenge of ...

A magnificent period piece from mid-19th-century Russia has just received a bit of a renovation. Five elements at the heart of the periodic table will never look the same again, following an update to ...

Just as the weight listed on your driver’s license doesn’t necessarily reflect your actual poundage, the official atomic weights of most chemical elements are actually more like ballpark estimates ...