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.
Best Answer: The chemical formula for quartz is SiO2, or silicon dioxide. Each silicon atom is covalently bonded to 4 oxygen atoms, and each oxygen atom is covalently bonded to 2 silicon atoms. So we have two oxygen atoms for every silicon atom, resulting in an empirical formula of SiO2.