Introduction

The Internet Resources

• The Chloring Institute, Inc. - This website offers lots of valuable information concerning the benefits and many uses of the element chlorine. Be sure to click on the link 'Benefits of Chlorine.' This website, although brief, provides very necessary information for one to begin their study of chlorine. One common known fact that I came across on this website was, that chlorine can be used in bleaching, in swimming pools, and to disinfect water for drinking. A very useful part of this website is the link 'what's new', as it provides even more links to current newsletters of chlroine. This would allow you to be constantly aware of new discoveries surrounding this element. The information given is very simple and basic. Therefore, I would recommend this website to either a child or a middle school student.

• Chlorine (Basic Information) - Scientific and basic information is given at this website. The most important aspect of this site is the facts written right at the beginning. For example, the atomic number is 17, the atomic weight is 35.453 g, the atomic radius is 99 pm, and the boiling point is -34.4 degrees C. This is extremely pertinent information to one who seeks further understanding of the element chlorine. It also contains a brief history of the element. It mentions that chlorine was discovered in 1774 by Scheele. Furthermore, the sources. properties, uses, and handling of chlorine are described. I would strongly recommend this site as either a basis of information for further investigation, or a brief summary. Therefore, this site can be facilitated by both adults and middle school students.

• Chlorine (Chemical Structure) - This website summarizes the chemical makeup of chlorine. It provides basic information such as the website above, but it area of information is quite different. At the top of the page the essentials are given. This includes the name, the symbol, the atomic number, the atomic weight, the group number, the group name. and a lot of other information. In addition, the color, standard states, and other important physical descriptions are described. An excellent picture of the element is even shown. The site describes chlorine's reactions with other various chemicals, and the isolation of chlorine. There is also a cute cartoon drawn on the site. This is by far the best website I have seen. The descriptions are quite involved and complex, so I would recomment this to advanced high school students, college students, and adults.

• Toxicity, Chlorine Gas - This website is about the toxicity of chlorine gas. It gives an in-depth analysis of symptoms and results of chlorine gas on human beings. It mentions that chlorine gas primarily has effects on the upper respiratory system. In fact, chlorine gas was used as a chemical weapon against American soldiers in World War I. Following a list of interesting facts about its uses, is a paragraph explaining the basic properties of chlorine gas. This includes the color, its combustibility, its solubility in water, and the other chemicals it can combine with. Then, the website goes into a lot more depth about the effects of different forms of chlorine gas poisoning. I found some of the symptoms of the poisoning quite interesting. For example, one of the symptoms is inflammation of the nose, pharynx, larynx, trachea, and bronchi. This is followed by pulmonary congestion. Chlorine gas can even cause burns and corneal abrasions. Further down the site, the frequency of the poisoning is written. In 1983, an estimated 191,000 US workers were at risk of exposure to chlorine in various forms. All of the symptoms and the causes are bulleted. For the benefit of those who might be worried about having chlorine poisoning, a list of tests and procedures to check are given. After this, a long list of emergency care and treatment is written. It even lists drugs that can be taken to counteract the effects of inhaled chlorine. One drug in particular that can be used is sodium bicarbonate. This site is extremely difficult to read and understand because it is very fact dense. I would only recommend this to college students, doctors, or people who are afraid they might have poisoning from chlorine gas.

• Periodic Table: Chlorine - This particular website was very short and basic. It contained the general information, such as the symbol, atomic number, atomic mass, melting point, boiling point, number of electrons and protons and neutrons, the classification, the crystal structure, the density and the color. This website does not contain nearly as much information as the previous sites. The only detail which sets this website apart are a diagram of a chlorine atom with its energy levels, a list of isotopes, and some basic facts about its discovery. I learned that chlorine is obtained from salt, and that its name originates from the Greek word khlôros, meaning green. This website is very visual and simple. However, very little information is given. I believe it would be most suitable for an elementary or middle school student.

• Chlorine (History) - This website does not offer any further basic information about chlorine. Similar to the other sites, it mentioned general information, its different states, its energies, its appearance, its characteristics, its reactions with other chemicals, its conductivity, and its abundance. Although this website does not offer more information than the previous websites, it is very helpful, since it pulls all of the information. In addition to this, it offers a lot of information about the history of the chemical. Did you know that in nature, chlorine can be found in the combined state only? Also, the liquid form of chlorine burns the skin. I would recommend this site to people of all ages, since it can be used either as all the infomation or as a basis for more information. The site is a perfect introduction to the chemical.

• Chlorine-Life Depends On It - This site strongly encourages the importance of the element. For instance, it opens with captivating question, 'What do a computer, a blood bag, and an Ecuadorian tree frog have in common?' Upon clicking on the link the answer, I discovered that they all contain chlorine. In fact, it was for this very reason, that the chlorine industry chose the Ecuadorian tree frog to be its symbol. At the bottom of the website are three links titled 'Find out more about chlorine', 'Find out more about Chlement', and 'How to view this site at its best.' I strongly advise that you click on the first link. This brings up a long description of what chlorine really is, and some key facts of chlorine industry . Did you know that when the Peruvian Government decided to remove the chlorine from the country's water supply in 1991, there was a cholera epidemic. Also, chlorine and its derivatives are used to treat sewage and industrial effluent, and as household and industrial bleaches to maintain and improve hygiene standards. As a whole, this website did not have a lot of information, but the selective information was very different from most websites. The focus was on the importance of chlorine, and chlorine industry. This website is truly appropriate for people of all ages because it includes a lot of pertinent facts, yet the language employed is very simple.

• Chlorine (Reactions) - The site opens with the common information about the element including the atomic number, the atomic mass, and much more. Then, the discovery of the element is briefly described. Underneath the next topic, it mentions that chlorine never exists in its free elemental state in nature. This is due to its high reactibility. It proceeds to describe the preparation, manufacture, and properties of chlorine. The rest of the website thoroughly describes chlorine's reactions with different substances. I found chlorine's reaction with hydrogen to be the most exciting. A mixture of Chlorine and Hydrogen explodes when exposed to sunlight to give Hydrogen Chloride. However, light is required for this reaction to occur. Furthermore, the website lists some of chlorine's uses. For example, the element can be used for the extraction of Gold from its ores. I found this website to be very useful for someone seeking information concerning chlorine. Furthermore, the website gives lots of information without being extremely lengthy. I would recommend this site to high school students, college students, and adults.

• Chlorine Online - Glossary - I found this website to be very unhelpful because the only part of the website dedicated the study of chlorine was one paragraph. In addition, the paragraph only consisted of a brief description of the element. It stated that chlorine is a yellowish-green gas, and its melting point is -37 degrees C. Also, that chlorine is the most common element in the earth's crust. This is essentially all the knowledge given. Although I would not recommend this website in general for retrieiving information about the element, it could be quite useful for a brief introduction. There is so little about the element in the website, that it is difficult to recommend it to a particular group of people. I suppose it would be appropriate for all ages.

• Visual Elements - This website focuses primarily on the visual aspects of the element chlorine. It shows a very distinct image of chlorine. The site even allows you to click on a link titled ' Click here to see larger version of this image.' It also describes in detail the appearance of chlorine. For instance, chlorine is 'a yellow-ish green dense gas with a choking hazard.' In addition, it give some background information concerning the element. Did you know that the origin of the name chlorine comes from the Greek word 'chloros' meaning pale green. Overall, this website is very short, and does not offer that much information. The one great part of this website is the image. In fact, this is the only website thus far that has a picture of chlorine. I would recommend this website to everyone who wishes to gain a visual version of information about chlorine. This image would be perfect for a project or presentation.

• Pool Info - In this website, you will find information specific to use of chlorine in pools. The first title is 'What's the history of chlorine...' Under this, it says that chlorine was discovered in the sixteenth century. Then it describes how chlorine is made and how chlorine works to synthesize. When chlorine is added to water, hypochlorous acid and hydrochloric acid is formed. These chemicals kill microorganisms by penetrating the cell walls, and destroying the inner enzymes, structures and processes. The most interesting topic was ' Is chlorine dangerous, unsafe, or unhealthy?' According to the site, chlorine is hazardous, with some forms more dangerous than others. There are many different types of chlorine. There are many other interesting topics as well. This is definitley one of the best sites that I have seen so far because of the amount of information given. In addition, the language used is very easy to understand. I thought that the site was very organized, making it easier to navigate. Due to the language used, I would recommend this website to middle school and high school students.

• ChemGlobe - This website shows mostly statistics and facts about chlorine. This website contains the most detailed of information. It tells the symbol, atomic number, atomic mass, group, shells, orbitals, electronegativity, ionization potential, ionization potential, oxidation states, electrical conductivity, melting point, boiling point, specific heat, heat of fusion, heat of vaporization, thermal conductivity, atomic radius, ionic radius, covalent radius, atomic volume, density, and crystal structure. All of the isotopes are listed, as well as various other information. In other information, I learned that chlorine was first discovered in Sweden. This website was detailed and gave a lot of pertinent information. I would recommend this site only to college students and adults because the terms used are very difficult to understand without having a lot of background information about chemistry.