Elements in the oxygen family are collectively called the Chalogens.
The oxygen family consists of sulfur, selenium, tellurium, polonium and, of course, oxygen. The family's elements all have six "valence" electrons in their outer shell, and the metallic character of the elements increases as you move down the periodic table. Other characteristics that increase as you move down the periodic table are melting point, boiling point, density, atomic radius, and ionic radius.
Oxygen
Colorless, odorless and tasteless, the oxygen family's main element exists as a gas at room temperature. Oxygen is the most abundant element in sea water and the Earth's crust and is the second most abundant element in the atmosphere. Nitrogen is the most abundant. Oxygen gas is used for steel, iron, general chemical manufacturing and is commonly used for water treatment. Oxygen is also made commercially by the fractional distillation of air in liquid form.
Sulfur
A solid at room temperature, sulfur has been mined to the point of raising concern over emissions from related industrial processes. Popular applications include the vulcanization of rubber and as a fungicide for strawberries and grapes. The mineral's distinct "rotten egg" smell is produced when sulfur dioxide escapes into the air. Sulfuric acid, produced in part from sulfur dioxide and sulfur trioxide, is used to make fertilizers. Mud baths that contain sulfur are known to help treat arthritis and certain skin disorders.
Selenium
Selenium is required by many animals as a micronutrient, but the element is toxic in large doses. In humans this nonmetal is essential for maintaining thyroid gland function. Certain studies suggest it may play a role in maintaining the immune system. The trace mineral contributes to good health but is only needed in small amounts. Selenoproteins (made when selenium is incorporated into proteins) act as antioxidants to protect cells against damage caused by free radicals and other disease-causing agents.
Tellurium and Polonium
Tellurium is a metalloid used in computer memory chips and solar panels. Although the element isn't toxic or carcinogenic to humans, overexposure is known to cause garlic-like breath. The metalloid is used to strengthen rubber and added to lead to protect it against corrosion. Most tellurium is thought to be found in coal. The rare and radioactive metal polonium has 33 different isotopes and is highly toxic over time or fatal if applied at the correct dosage. Discovered by Pierre and Marie Curie in 1898, the radioactive element was named after Poland. Polonium-210 is the only isotope that occurs naturally.
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