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In quantum chemistry, the quantum theory of atoms in molecules (QTAIM), sometimes referred to as atoms in molecules (AIM), is a model of molecular and condensed matter electronic systems (such as crystals) in which the principal objects of molecular structure - atoms and bonds - are natural expressions of a system's observable electron density distribution function.
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).
Body composition may be analyzed in various ways. This can be done in terms of the chemical elements present, or by molecular structure e.g., water, protein, fats (or lipids), hydroxyapatite (in bones), carbohydrates (such as glycogen and glucose) and DNA.
For example, a molecule can be viewed as a grouping of elements, and an atom can be further divided into subatomic particles (these levels are outside the scope of biological organisation). Each level can also be broken down into its own hierarchy, and specific types of these biological objects can have their own hierarchical scheme.
Serotonin (/ ˌ s ɛr ə ˈ t oʊ n ɪ n, ˌ s ɪər ə-/) [6] [7] [8] or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter.Its biological function is complex, touching on diverse functions including mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vasoconstriction.
Atomic, molecular, and optical physics (AMO) is the study of matter–matter and light–matter interactions, at the scale of one or a few atoms [1] and energy scales around several electron volts. [2]: 1356 [3] The three areas are closely interrelated. AMO theory includes classical, semi-classical and quantum treatments.
The term, "molecular model" refer to systems that contain one or more explicit atoms (although solvent atoms may be represented implicitly) and where nuclear structure is neglected. The electronic structure is often also omitted unless it is necessary in illustrating the function of the molecule being modeled.
Molecular biology is the study of the molecular underpinnings of the biological phenomena, focusing on molecular synthesis, modification, mechanisms and interactions. Biochemistry is the study of the chemical substances and vital processes occurring in living organisms .