Chemistry
Chemistry is the scientific discipline involved with compounds composed of atoms, i.e. elements, and molecules, i.e. combinations of atoms: their composition, structure, properties, behavior and the changes they undergo during a reaction with other compounds. Chemistry addresses topics such as how atoms and molecules interact via chemical bonds to form new chemical compounds. There are four types of chemical bonds: covalent bonds, in which compounds share one or more electron(s); ionic bonds, in which a compound donates one or more electrons to another compound to produce ions (cations and anions); hydrogen bonds; and Van der Waals force bonds.
Instrumental
An instrumental is a musical composition or recording without lyrics, or singing, although it might include some inarticulate vocals, such as shouted backup vocals in a Big Band setting. The word "song" is widely misused by people in the popular music industry to describe any musical composition, whether sung or played only by instruments."The music is primarily or exclusively produced by musical instruments. An instrumental can exist in music notation, after it is written by a composer; in the mind of the composer (especially in cases where the composer himself will perform the piece, as in the case of a blues solo guitarist or a folk music fiddle player); as a piece that is performed live by a single instrumentalist or a musical ensemble, which could range in size from a duo or trio to a large Big Band, concert band or orchestra.