Chlorine

by Kristin Kuhn

First let me tell you a little bit about my historical background. There are two chemists that have been very influential in my development. One of them is Carl Wilhelm Scheele. In 1774 Carl isolated me in his experiment with pyrolusite, but believed that I was a compound. Many say that he isolated me. The other important figure in my life is Sir Humphry Davy. He took was Scheele had discovered a step further by proving that I was an element, and then naming me chlorine.

As I mentioned earlier, you probably think of me when around something with an antiseptic smell. I actually have many more interesting characteristics that I am sure you are eager to learn about. I am a nonmetal that exists as a greenish-yellow, highly corrosive gas. At room temperature, my melting point is -100.98° C and boiling point is -34° C. In the periodic table, I am a member of Group VIIA, or halogen, elements. Being a halogen means I am a very reactive ion, forming -1 bonds with nearly all metals. One of my best friends is sodium because together we form my best know compound, sodium chloride. I do not occur freely in nature, but my compound are common in minerals. I am very proud to be the twentieth most abundant element in the earth’s crust. Other factual information about me includes: my symbol is Cl, my atomic number is 17 and my atomic weight is 35.433.

I know I have many agreeable traits, but you have to be careful if you want to become real good friends with me. It is important that you not inhale even the smallest doses of me at room temperature. I can be dangerous to your health. After all, I was the first substance used as a poison gas in World War I. If you want to appreciate my suffocating odor, you can experience it safely around large swimming pools or areas where chlorine bleach is being used.

Life for you humans just wouldn’t be the same without me around. I make water safe for your consumption by destroying germ life. I am used for bleaching paper pulp and other organic materials. I also help prepare important products such as tetraethyl lead. I am mainly produced by the electrolysis of a salt solution, with sodium hydroxide as a by product. Because the demand for me is greater that the need for sodium hydroxide, I am sometimes produced by treating salt with nitrogen oxides. I get to travel form place to place in steel bottles or tank cars. I travel as a liquid.

Now that you have learned many of my very important traits, I would like to talk to you a little bit about my friend Chlora. Chlora is a mole. Do you know what a mole is? A mole is a base unit of the International System of Units. It is defined by Microsoft Encarta as the amount of a substance that contains as many elementary particles as the number of carbon atoms in 0.012kg of carbon-12. This number of carbon atoms contained in 12g of carbon-12 is 6.02´ 1023. This number is called Avogadro’s number. In simple terms a mole is an amount of any substance that weighs, in grams, as much as the equivalent atomic weight of that substance. Now that you know what a mole is, you are probably curious about Chlora. She doesn’t look like mole the measurement, but mole the animal. She is very closely connected with me. She has blonde hair with streaks of green because I dye her hair when she swims in the pool. The pool is her favorite hangout. Since I am a chemical in the water I get to talk to her all the time. She even says that when she is out of the pool she can still smell me on her skin. Chlora is one of my closest friends. You should talk to her sometime. She knows a lot about me and will be happy to share information with you.