Molecular mass or molecular weight refers to the mass of a molecule. It is calculated as the sum of the mass of each constituent atom multiplied by the number of atoms of that element in the molecular formula. The molecular mass of small to medium size molecules, measured by mass spectrometry, determines stoichiometry. For large molecules such as proteins, methods based on viscosity and light-scattering can be used to determine molecular mass when crystallographic data are not available.
A methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms — CH3. The group is often abbreviated Me. Such hydrocarbon groups occur in many organic compounds. It is a very stable group in most molecules. While the methyl group is usually part of a larger molecule, it can be found on its own in either of three forms: anion, cation or radical. The anion has eight valence electrons, the radical seven and the cation six. All three forms are highly reactive and rarely observed.
Science of drugs including their origin, composition, pharmacokinetics,
pharmacodynamics, therapeutic use, and toxicology.
Pharmacology (from Greek φάρμακον, pharmakon, "poison" in classic Greek; "drug" in modern Greek; and -λογία, -logia "study of", "knowledge of") is the branch of medicine and biology concerned with the study of drug action, where a drug can be broadly defined as any man-made, natural, or endogenous (within the body) molecule which exerts a biochemical and/or physiological effect on the cell, tissue, organ, or organism. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals.