Medical Definition of Contraceptive, pill. Contraceptive, pill: Commonly called the pill, combined oral contraceptives are the most commonly used form of reversible birth control in the United States. This form of birth control suppresses ovulation (the monthly release of an egg from the ovaries) by the combined actions of the hormones estrogen and progestin. If a woman remembers to take the pill every day as directed, she has an extremely low chance of becoming pregnant in a year.
Silicon is a chemical element with symbol Si and atomic number 14. A hard and brittle crystalline solid with a blue-gray metallic luster, it is a tetravalent metalloid. It is a member of group 14 in the periodic table, along with carbon above it and germanium, tin, lead, and flerovium below.
Silicon dioxide, also known as silica (from the Latin silex), is a chemical compound that is an oxide of silicon with the chemical formula Si O 2. It has been known since ancient times.Silica is most commonly found in nature as quartz, as well as in various living organisms.n dimeric silicon dioxide there are two oxygen atoms bridging between the silicon atoms with an Si-O-Si angle of 94Â° and bond length of 164.6 pm and the terminal Si-O bond length is 150.2 pm.