Search results
Results from the WOW.Com Content Network
A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O 2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H 2 O).
A negatively charged ion; i.e. an atom or molecule with a net negative electric charge caused by an excess of electrons compared to protons. annulation The formation of a cyclic compound or ring structure from one or several acyclic precursors; or a reaction involving the addition of a ring structure to another molecule via two new bonds. [2 ...
Theories of chemical structure were first developed by August Kekulé, Archibald Scott Couper, and Aleksandr Butlerov, among others, from about 1858. [4] These theories were first to state that chemical compounds are not a random cluster of atoms and functional groups, but rather had a definite order defined by the valency of the atoms composing the molecule, giving the molecules a three ...
A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. [ 16 ] [ 17 ] [ 18 ] A molecule may be homonuclear , that is, it consists of atoms of one chemical element, as with two atoms in the oxygen molecule (O 2 ); or it may be heteronuclear , a chemical compound composed of more than one element, as with ...
3' untranslated region (3'-UTR). Also three-prime untranslated region, 3' non-translated region (3'-NTR), and trailer sequence.. 3'-end. Also three-prime end.. One of two ends of a single linear strand of DNA or RNA, specifically the end at which the chain of nucleotides terminates at the third carbon atom in the furanose ring of deoxyribose or ribose (i.e. the terminus at which the 3' carbon ...
The definition has historically branched from simply molecule to monatomic and polyatomic molecule to the quantum chemical concept of everything in a potential well is a molecule, when, in fact, the simplest, original definition will always give the clearest picture of what this concept is all about: smallest particle of a substance still ...
An atom is a body which cannot be cut in two; a molecule is the smallest possible portion of a particular substance. After speaking about the atomic theory of Democritus , Maxwell goes on to tell us that the word 'molecule' is a modern word.
The terms polymer and macromolecule do not mean the same thing. A polymer is a substance composed of macromolecules. The latter usually have a range of molar masses (unit g mol −1), the distributions of which are indicated by dispersity (Đ).