The terms theory and model are defined, and students learn how a theory remains valid. Atomic Theory: The Development of the Atomic Theory: The terms theory and model are defined, and students learn ...

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) ...

Before you submit an error, please consult our Video Help page. Science Trek is available to stream on pbs.org and the free PBS App, available on iPhone, Apple TV, Android TV, Android smartphones, ...

DISCUSSING the unit of atomic weight before Section A (Physics) at the meeting of the British Association in London on Sept. 28, Dr. F. W. Aston contrasted the point of view of the physicist and the ...