For decades students have been taught the Octet Rule, which states that atoms want to have eight electrons in their valence shells. When you know how many electrons an atom has in its outer shell, you know how it will gain, lose, or share electrons to form complete octets, which tells you the number of bonds the atom can form. The real world of molecular bonding doesn't neatly conform to this rule, however. Hypervalent molecules form more than the expected number of bonds, appearing to stuff their valence shells with more than eight electrons. The greenhouse gas sulfur hexafluoride (SF6) is one example; another is chlorine trifluoride (ClF3), a gas used in rocket fuel, nuclear fuel processing, and etching operations in the semiconductor industry. It turns out, many molecules break the Octet "Rule."
Our goal was to create a three-layer density column in a test tube using only sugar, food coloring, and water.Students learned that cold water is more dense than hot water and that keeping the volume of a solution the same, but messing with the mass of it, will alter density.Here are some pictures of selected columns.It took us two days, but everyone completed the task…..
The first two Earth-sized exoplanets, Kepler-20e and Kepler-20f, are depicted here compared to Earth and Venus. Scientists think Kepler-20f could have an atmosphere, but suggest that extremely hot conditions on Kepler-20e would have evaporated any atmosphere.
Colliding protons create a splash of particles streaking outward along paths (yellow) reconstructed here from data collected by the CMS detector at CERN’s Large Hadron Collider. A pair of photons emerging from this smash-up (red bars) qualify this event as a potential Higgs sighting. Credit: CERN