Astronomy
Stellar Evolution: Brown Dwarfs, Supernovas, and Black Holes
Differently sized stars have different fates. While stars that are smaller than the Sun end up as brown dwarfs, those that are larger end in supernova explosions. […]
Professor Robert M. Hazen
Astronomy
The Sun’s Life Cycle and Evolution: Models and Theories
The Sun goes through many stages in its life cycle. After years of observing the Sun, many different models of the its life cycle and evolution have been developed. […]
Astronomy
Observing the Sun: Its Structure and Layers
Because of its closeness to the Earth, the Sun is the most thoroughly studied star. Our knowledge of the Sun and the observations of distant stars help us understand the life cycles of other stars. […]
Chemistry
Implications and Consequences of the Periodic Table
The periodic table of chemical elements is systematized. Elements are arranged in rows and columns according to their weight and chemical properties. […]
Chemistry
Completing Mendeleev’s Periodic Table
The periodic table had clear gaps that required predictions, and many of those predictions were filled when new elements predicted by Mendeleev were subsequently discovered. […]
Chemistry
How Dmitri Mendeleev Organized the Chemical Elements
Dmitri Mendeleev systematized the 63 chemical elements into the periodic table. The elements were organized into columns according to their chemical behavior and in rows according to their weights. […]
Chemistry
The Concept of Chemical Elements
Throughout the 18th and 19th centuries, chemists identified more and more new chemical elements, adding to the dozen or so elements that had been known to the ancients. […]
History of Science
Early Theories of Atomic Structure: J.J. Thomson and Ernest Rutherford
The observations from various scientific experiments all provided better indications to the structure of atoms. […]
History of Science
Scientific Evidence for Atomic Theory: Radioactivity, Mathematics, and Imaging
The observations from various scientific phenomena all indicate that the atomic theory is a valid scientific theory. […]
History of Science
Bernoulli and Dalton: Early Applications of the Atomic Theory
The atomic theory is one of the transforming events in all of science. Daniel Bernoulli and John Dalton made crucial scientific observations that changed the way we thought about atoms. […]