Chalcogens

1. Chalcogens Taylor Lister Gabe May Octavia Geiger

2. Oxygen family • All elements of the Oxygen family have 6 electrons in their outermost shell, with a valence electron configuration of ns2np4, which accounts for the similar chemical properties between the elements. As one moves down the group, metallic character increases, with tellurium being a metalloid and polonium a metal. Melting point, boiling point, density, atomic radius, and ionic radius all increase going down the group. Ionization energy decreases going down the group. The most common oxidation state is -2, however sulfur can also exist at a +4 and +6 state and +2, +4, and +6 oxidation states are possible for Se, Te, and Po.

3. Breakdown of uses and appearances Oxygen: Oxygen is a gas at room temperature and 1 atm, and is colorless, odorless, and tasteless. When in its liquid form it has a bluish color. It is the most abundant element in the Earth's crust and the most abundant element in sea water. There are many commercial uses for oxygen gas, which is typically obtained through the process of fractional distillation. It is used in the manufacture of iron, steel, and other chemical manufacturing. It is also used in water treatment, as an oxidizer in rocket fuel, for medicinal purposes, and in petroleum refining. Sulfur: is a solid at room temperature and 1 atm pressure. It exists in a variety of forms naturally, including elemental sulfur, sulfides, sulfates, and organic-sulfur compounds. Sulfur produced from this process is used in a variety of ways including in vulcanizing rubber and as fungicide to protest grapes and strawberries.  Selenium: Selenium can be seen as a red or black amorphous, or a red or grey crystaline structure, which is its most stable structure. It acts as a semiconductor and therefore is often used in the manufacture of rectifiers, which are devices that convert alternating currents to direct currents. It is used in the drums of laser printers and copiers. In addition, it has found increased use now that lead has been removed from plumbing brasses

4. Breakdown of uses and appearances (cont.) • Tellurium: the metalloid of the Oxygen family, with a silvery white color and a metallic luster similar to tin at room temperature. Like selenium, it is also displays photoconductivity. It is an extremely rare element, and is most commonly found as a telluride of gold. It is often used in metallurgy in combination with copper, lead, and iron. In addition, it is used in solar panels and memory chips for computers. It is not toxic or carcinogenic, however when humans get exposed to too much of it they develop a garlic-like breath.   Polonium: a very rare, radioactive metal. It does not exist in nature in compounds, however it can be manipulated to form ones synthetically in the lab. It is used as an alloy with beryllium to act as a neutron source for nuclear weapons. It is a highly toxic element. The radiation it emits makes it very dangerous to handle. It can be immediately lethal when applied at the correct dosage, or cause cancer if long-term exposure to the radiation occurs. Methods to treat humans who have been contaminated with polonium are still being researched, and it has been shown that chelation agents could possible help to decontaminate humans.

5. Chemical Properties and Reactions • As the atomic number increases the amount of metal in the element also increases • The nonmetals of the group are oxygen and sulfur, the metalloids are selenium and tellurium, and the only metal is polonium

6. Chemical Properties and Reactions (cont.) • Covalent bonds are more frequent in the smaller members of the group • All the elements can be found naturally as ions

7. Reasons for similarities • Gains two electrons • Forms doubly charged negative ion which means forms stable configuration • Ores of copper • The energy is all around the 1,000 • All the ionic radius is larger then the atomic radius

8. http://www.youtube.com/watch?v=Vz542SjGUhA