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1950 - Arthur Jeffrey Dempster died. Dempster was a Canadian-American physicist who designed and built the first mass spectrometer. Mass spectrometers are used to separate a sample's components by mass. He later used this device to discover the uranium isotope U-235, the main isotope used in atomic bombs. 1920 - Nicolaas Bloembergen was born. Bloembergen is a Dutch-American physicist who shares half the 1981 Nobel Prize in Physics with Arthur Schawlow for the development of laser spectroscopy. Kai Siegbahn's research into the development of electron spectroscopy earned him the other half of the prize. 1892 - Archibald Scott Couper died. James Irvine/Journal of Chemical Education (1930)Couper was a Scottish chemist who described the methods carbon atoms could bond together to form large molecules. He was also the first to describe molecules by element symbols connected by dashes to represent the bonds between the atoms. 1818 - Henri-Étienne Sainte-Claire Deville was...

March 11th marks the passing of Archibald Scott Couper. Couper was a Scottish chemist who discovered carbon atoms were tetravalent and could form long chain molecules. Prior to this discovery, molecules were believed to possess one central atom, but the structures of many organic compounds could not be explained by this theory. Couper passed his paper to Charles Adolphe Wurtz to present at the French Academy of Sciences. Unfortunately, Wurtz procrastinated on passing the paper to the Academy and Couper lost priority to German chemist, August Kerkule who also discovered carbon could form bonds and determined the ring structure of benzene. Couper did not take the loss well and never published a scientific paper for the rest of his life. One lasting contribution Couper gave to chemistry was the way chemical structures are drawn. He was the the first to draw structures where element symbols were connected by lines that represent the bonds between them. Find out what else occurred on th...

Here's a fun Easter project for you: crystallize sugar onto string to make an Easter egg basket or a special holiday decoration. The project is similar to growing rock candy crystals except these sugar crystals form much more quickly and are used to form a construction material rather than a tasty crystal treat. Transcript: How to Make Rock Candy Hi, I'm Dr. Anne Helmenstine for About.com. Have you seen brightly colored rock candy in a store or used to sweeten a drink? Rock candy is simply sugar crystals. I'm going to show you how you can make rock candy yourself, in any color or flavor you like. Are you ready? Let's get started. Rock Candy Ingredients The only two ingredients you need for rock candy are sugar and water, though you can add food coloring and flavoring if you want colored and flavored crystals.

March 10th is Jeremias Benjamin Richter's birthday. Richter was a German chemist who introduced the term stoichiometry to chemistry. He noticed the ratio of reactants by weight used in a chemical reaction was always the same. This lead to the law of equivalent or multiple proportions. This discovery was one of the first steps towards a new atomic model of chemical reactions. Stoichiometry and balancing chemical equations are basic principles learned early in chemistry. Find out how to balance chemical equations or test your knowledge of stoichiometry and find out what else occurred on

Did you know about 2.6 billion people (~40% of the world's population) do not have access to a toilet? Although this is a problem you hopefully don't encounter, it is a major health concern since untreated human feces contaminate the water supply and cause deaths from diarrhea. A Swedish company has a developed a new disposable toilet that it believes will help combat this problem by providing toilets to people at a price point they may be able to afford. The Peepoo is a biodegradable plastic bag that contains an inner gauze that has been coated with a film of urea. A person uses the Peepoo, ties up the bag, and then buries it. According to a New York Times article, the urea crystals kill the pathogens and break the waste into a safe fertilizer. The bags will sell for around 2-3 cents, which is about the same cost as an ordinary plastic bag. Anders Wilhelmson, inventor of the Peepoo, has tested the bags in India and Kenya, where slum dwellers dispose of waste by collecting i...

Did you know about 2.6 billion people (~40% of the world's population) do not have access to a toilet? Although this is a problem you hopefully don't encounter, it is a major health concern since untreated human feces contaminate the water supply and cause deaths from diarrhea. A Swedish company has a developed a new disposable toilet that it believes will help combat this problem by providing toilets to people at a price point they may be able to afford. The Peepoo is a biodegradable plastic bag that contains an inner gauze that has been coated with a film of urea. A person uses the Peepoo, ties up the bag, and then buries it. According to a New York Times article, the urea crystals kill the pathogens and break the waste into a safe fertilizer. The bags will sell for around 2-3 cents, which is about the same cost as an ordinary plastic bag. Anders Wilhelmson, inventor of the Peepoo, has tested the bags in India and Kenya, where slum dwellers dispose of waste by collecting i...

 If I asked you to name a liquid element, you'd probably say 'mercury', which is liquid at room temperature. So are a few other elements, plus just about any element can turn into a liquid if the temperature and pressure are right. Do you know which element is pictured here, yellow as a solid and melting into a red liquid?

March 9th is Stanley Thompson's birthday. Thompson was an American nuclear chemist when nuclear chemistry was a brand new subject. In the early days of the Manhattan Project plutonium was produced in very small quantities, typically on the order of micrograms. Thompson was the chemist who developed the process that allowed the refining of plutonium on an industrial scale to amounts that would enable practical applications.

Did you know bananas are slightly radioactive? Bananas contain high levels of potassium. Radioactive K-40 has an isotopic abundance of 0.01% and a half-life of 1.25 billion years.

ScienceDaily reports that University of Florida engineers have made a flat surface that is so hydrophobic that it basically won't get wet. The water-repellent surface was formed by arranging microscopic plastic fibers such that they mimic the the hairs of spiders. The hairs of water spiders are both long and short, with varying degrees of curvature, and arranged chaotically over the spider's body, enabling the spider to trap air bubbles so that it can breathe underwater.

It's not very often scientists get to say they have found a new way to generate electricity, but that's exactly what researchers at MIT have done. An Inhabit.com article and PhysOrg.com article describe the discovery of thermopower. MIT chemical engineer Michael Strano and mechanical engineering student Wonjoon Choi and their team produced thermopower waves by coating a carbon nanotube with a fuel and igniting the fuel.

March 7th is the English astronomer, Sir John Frederick William Herschel's birthday. He was one of the better known English scientists of the time and made several contributions to astronomy. One contribution he was credited for was the discovery of life on the Moon. Starting on August 25, 1835, six articles were published by the New York Sun newspaper describing Herschel's observation of Moon creatures such as unicorns, bipedal beavers and bat-winged humanoids. The Great Moon Hoax was written by Richard A. Locke to increase circulation for the New York Sun. It wasn't exposed as a hoax for two weeks and no retraction was ever made. Herschel was initially amused by the stories, but grew tired of trying to explain to people he had nothing to do with it or denying the observations to people who believed the hoax. Find out what else occurred on this day in science history.

Have you ever wanted to color your urine or wondered what causes urine to become colored? If so, you're in luck, because I have the answer! Here's a little applied color chemistry for your entertainment and experimentation pleasure: Violet - I'm going out on a limb here, but I suspect you could get violet or purple urine if you combined beets with methylene blue. Blue - Methylene blue will turn your urine blue or greenish-blue. It can also color the whites of your eyes blue. The coloration of both urine and eyes is reversible. At one time, methylene blue was considered to be an effective treatment against malaria. As far as urine colorants go, this one is considered to be reasonably safe to eat, though you should be aware some people are allergic to methylene blue. Food coloring may turn your urine blue. A rare, inherited disease known as porphyria can cause blue urine. King George III's blue urine may have been attributable to porphyria.

In addition to making a human battery using sodium metal, you can perform a chemistry demonstration showing the vigorous chemical reaction between sodium and water. However, it is important to use a small amount of sodium metal (a piece smaller than the size of a pencil eraser). If you use too much sodium, there is a tendency for the heat produced by the reaction to melt the remaining sodium metal, which suddenly increases the surface area available to react with water. The result may be an explosion of hot sodium metal shrapnel and lye solution.

The usual method of connecting the half-cells of a galvanic cell is to use a salt bridge as a source of mobile ions, like in this diagram. However, you can use your fingers in place of the salt bridge. Make a 'V' with two fingers of your hand. Simply dip one finger in the beaker of copper metal in 1M copper sulfate solution and another finger in the beaker of zinc metal in 1M zinc sulfate solution. You just made a battery out of yourself! Your human battery will have about the same voltage as the standard cell potential. Rinse your fingers when you are done and congratulate yourself on being such an excellent source of ions. Advanced Human Battery Do you want more voltage? Switch out the zinc for a more reactive metal and get your friends in on the action. You can make a sodium-copper battery by having one lucky volunteer touch a small piece of sodium metal. Have the next person join hands with the person touching the sodium. Make a chain of human hands with as many peop...

If you've ever seen a mummy in a museum, you might have thought the ancients went a little overboard with henna and other red dyes. While people have colored their hair practically forever, it's more likely what you're seeing is the change in haircolor that occurs after a person dies. The color of hair comes from the mixture of two melanin pigments: eumelanin (yellow-brown-black) and pheomelanin (red). Pheomelanin is more stable, so over time the eumelanin oxidizes while most of the pheomelanin remains. This is reason most Egypian mummies appear to have reddish hair. The change occurs more slowly under dry oxidizing conditions, such as burials in ice or sand, than under wet reducing conditions, such as burials in wooden coffins or damp caves. Therefore, you would expect to see a more faster or more dramatic haircolor change in a body from the jungle, for example, than a corpse from the desert.

Over 75% of women and a growing percentage of men color their hair. Do you know how haircoloring works? In the Beginning The first safe commercial haircolor was created in 1909 by French chemist Eugene Schuller, using the chemical paraphenylenediamine. How does haircolor work? It's the result of a series of chemical reactions between the molecules in hair, pigments, as well as peroxide and ammonia, if present. What is Hair? Hair is mainly keratin, the same protein found in skin and fingernails. The natural color of hair depends on the ratio and quantities of two other proteins, eumelanin and phaeomelanin. Eumelanin is responsible for brown to black hair shades while phaeomelanin is responsible for golden blond, ginger, and red colors. The absence of either type of melanin produces white/gray hair. Natural Colorants People have been coloring their hair for thousands of years using plants and minerals. Some of these natural agents contain pigments (e.g., henna, bla...

Freezing Point Depression and Colligative Properties You can make your own ice cream without using a freezer or ice cream maker . Materials 1/2 cup milk 1/2 cup whipping cream (heavy cream) 1/4 cup sugar 1/4 teaspoon vanilla or vanilla flavoring (vanillin) 1/2 to 3/4 cup sodium chloride (NaCl) as table salt or rock salt 2 cups ice 1-quart ZiplocTM bag 1-gallon ZiplocTM bag themometer measuring cups and spoons cups and spoons for eating your treat!