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 with a Coordination Number of Three. A coordination number of three is found for compounds in which the silicon extends a p Ï âp Ï bond to a partner. The usual condition is that the two other ligands to the silicon are sterically demanding, such as a phenyl group with substituents in the ortho position.