Daily Online News

February 6 th marks the passing of Joseph Priestley. Priestley was an English theologian and natural philosopher who is best known with this experimental works with gases or "airs". He was the first to identify several gases including the element oxygen. This discovery helped answer the old question: Why do things burn? The prevailing theory of the time held there was a substance present in all things called phlogiston. Things would burn until they become saturated with phlogiston and any fire would go out. Priestley's found his new air greatly increased the process of burning and called it "dephlogisticated air" since it appeared to contain no phlogiston. Even though his discovery seemed to support the phlogiston theory, it was one of the key elements to launch Lavoisier's chemical reaction theories that started the Chemical revolution of the 19 th Century. Priestley began his work with gases with a ready supply of phlogistated air, or carb...

One common chemistry homework assignment is finding atomic mass. The atomic mass is the sum of the masses of the protons, neutrons, and electrons in an atom, but the electrons have so much less mass than the protons and neutrons that they are left out of the calculations. Atomic mass thus becomes the sum of the mass of an atom's protons and neutrons. It's not difficult to find atomic mass, but there are three types of problems you may be asked to perform, depending how advanced your class is. Here's a look at how to find atomic mass, no matter how the problem is presented.