Atomic Structure An updated version of this lesson is available at Visionlearning: Atomic Theory & Ions & Isotopes In the last lesson we learned that atoms were particles of elements, substances that could not be broken down further. In examining atomic structure though, we have to clarify this statement. Atoms are made up of 3 types of particles , and . A neutron walked into a bar and asked how much for a drink. The bartender replied, "for you, no charge." -Jaime - Internet Chemistry Jokes The atom above, made up of one proton and one electron, is called hydrogen (the abbreviation for hydrogen is H). Keep in mind that atoms are extremely small. While you should keep in mind that electrons actually form clouds around their nucleii, we will continue to represent the electron as a spinning particle to keep things simple. In an electrically neutral atom, the positively charged protons are always balanced by an equal number of negatively charged electrons. As you can see, helium is larger than hydrogen.
Aster - Archives Aster devient Recherches en didactiques des sciences et des technologies à compter de janvier 2010. La revue Aster contribue au développement de la recherche en didactique des sciences et à la diffusion des connaissances qui permettent de mieux comprendre les situations d’enseignement-apprentissage, les contenus d’enseignement et l’organisation des plans d’étude. Elle s’intéresse aux processus d’accès aux savoirs, à la construction de compétences par les élèves et les étudiants, et à la professionnalisation des enseignants et des formateurs, tant dans des situations d'éducation formelle que non formelle. Aster publie des articles utilisant des méthodes variées et des cadres théoriques divers pour étudier ces questions de l'école à l'université et dans la formation des maîtres. La revue Aster est ouverte à des contributions internationales, favorisant ainsi la circulation d’idées dans le champ de la didactique des sciences.
Astronomy Picture of the Day 5 Really Weird Things About Water Water, good ol' H2O, seems like a pretty simple substance to you and me. But in reality, water - the foundation of life and most common of liquid - is really weird and scientists actually don't completely understand how water works. Here are 5 really weird things about water: 1. Hot Water Freezes Faster Than Cold Water Take two pails of water; fill one with hot water and the other one with cold water, and put them in the freezer. In 1963, a Tanzanian high-school student named Erasto B. Thankfully, Mpemba didn't back down - he convinced a physics professor to conduct an experiment which eventually confirmed his observations: in certain conditions, hot water indeed freezes before cold water*. Actually, Mpemba was in good company. But how do scientists explain this strange phenomenon? 2. Everybody knows that when you cool water to 0 °C (32 °F) it forms ice ... except that in some cases it doesn't! Note: Similarly, superheated water remains liquid even when heated past its boiling point. 3. 4.
Science.gouv.fr Titan « Lights in the Dark Illustration of a sunrise above a liquid methane lake on Titan. © Ron Miller. All rights reserved. We’ve known for quite some time now that lakes of liquid methane and ethane exist on the frigid surface of Saturn’s overcast moon Titan. While the sheer presence of large amounts of liquid on another world is fascinating, one thing that’s particularly intrigued scientists about these hydrocarbon lakes is their uncanny stillness — in many radar images they appear to be literally as smooth as glass, with no indication of movement or wave action of any sort. And although liquid methane isn’t water and probably behaves differently, with Titan’s substantial atmosphere it only makes sense that some sort of waves would get kicked up across lakes so vast, even from the most moderate seasonal breezes. Read the rest of this article here. Like this post? Like this: Like Loading...
Paul A.M. Dirac - Biography Paul Adrien Maurice Dirac was born on 8th August, 1902, at Bristol, England, his father being Swiss and his mother English. He was educated at the Merchant Venturer's Secondary School, Bristol, then went on to Bristol University. Here, he studied electrical engineering, obtaining the B.Sc. (Engineering) degree in 1921. Dirac's work has been concerned with the mathematical and theoretical aspects of quantum mechanics. The importance of Dirac's work lies essentially in his famous wave equation, which introduced special relativity into Schrödinger's equation. Dirac's publications include the books Quantum Theory of the Electron (1928) and The Principles of Quantum Mechanics (1930; 3rd ed. 1947). He was elected a Fellow of the Royal Society in 1930, being awarded the Society's Royal Medal and the Copley Medal. In 1937 he married Margit Wigner, of Budapest. From Nobel Lectures, Physics 1922-1941, Elsevier Publishing Company, Amsterdam, 1965 Paul A.M. Copyright © The Nobel Foundation 1933
Enseigner les Sciences, EE et EDD - Réseau social du Laboratoire de Didactique et d'Epistémologie des Sciences The Greatest Mysteries of Mars| Is there life on Mars? | Biggest Questions of the Universe | Space.com This is a portion of the first 360-degree view of the martian surface taken by Spirit's panoramic camera. Part of the spacecraft can be seen in the lower part of the image. PhotoCredit: NASA/JPL/Cornell Each Friday this summer, Life's Little Mysteries presents The Greatest Mysteries of the Cosmos, starting with our solar system. Mars, the fourth planet from the Sun, gets its name from the Roman god of war on account of its blood-rust color. Despite these setbacks, our curiosity regarding Mars has never abated. Abode of life? You can't talk about Mars without raising the question of life. "What everyone wants to know is: has the planet ever harbored life?" Today, and for most of its history, Mars has been a "cold, dry, desolate world," said Squyres. To make life, you (most likely) need water. Warm and wet to cold and dry The next biggest mystery concerning Mars is, "What happened?" A tale of two hemispheres Bonus boggler: Funky, lumpy moons
Short Words to Explain Relativity So, have a seat. Put your feet up. This may take some time. Can I get you some tea? Earl Grey? Okay. Okay. Say you woke up one day and your bed was gone. Now, let's add the bed back. Now, if I took the bed back but gave you the sun -- just you and the sun in the void, now -- I'll bet you'd say that the sun is so big, next to you, that odds are you move and not the sun. In a word, you can't find any one true "at rest". Aha, but now wait! Well, and so we went to test this idea out. To say that we were less than glad to find that out is to be kind. Old Al, he came out the blue and said, "Not only do rays move at c if what puts them out is held fast or not: they move at c even if you are held fast or not." But for that to be true, then time also has to get in on the act. I can hear you say, "No way. So you see, when you give up on the idea of a one true "at rest", then you have to give up on the idea of a one true time as well! What a snag, eh? But old Al's mind was set. But Herb -- what?