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Usage of the term to describe large molecules varies among the disciplines. For example, while biology refers to macromolecules as the four large molecules comprising living things, in chemistry , the term may refer to aggregates of two or more molecules held together by intermolecular forces rather than covalent bonds but which do not readily ...
Examples of network solids include diamond with a continuous network of carbon atoms and silicon dioxide or quartz with a continuous three-dimensional network of SiO 2 units. Graphite and the mica group of silicate minerals structurally consist of continuous two-dimensional sheets covalently bonded within the layer, with other bond types ...
Individual molecules have strong bonds that hold the atoms together, but generally, there are negligible forces of attraction between molecules. Such covalent substances are usually gases, for example, HCl, SO 2, CO 2, and CH 4. In molecular structures, there are weak forces of attraction.
A network covalent solid consists of atoms held together by a network of covalent bonds (pairs of electrons shared between atoms of similar electronegativity), and hence can be regarded as a single, large molecule. The classic example is diamond; other examples include silicon, [3] quartz and graphite.
A well-studied example is the radical ion salt TTF-TCNQ with a conductivity of 5 x 10 2 Ω −1 cm −1, [5] much closer to copper (ρ = 6 x 10 5 Ω −1 cm −1) [8] than many molecular solids. [31] [18] [30] The coulombic interaction in TTF-TCNQ stems from the large partial negative charge (δ = -0.59) on the cyano- moiety on TCNQ at room ...
Several non-metallic elements exist only as molecules in the environment either in compounds or as homonuclear molecules, not as free atoms: for example, hydrogen. While some people say a metallic crystal can be considered a single giant molecule held together by metallic bonding , [ 20 ] others point out that metals behave very differently ...
This is an index of lists of molecules (i.e. by year, number of atoms, etc.). Millions of molecules have existed in the universe since before the formation of Earth. Three of them, carbon dioxide , water and oxygen were necessary for the growth of life.
A biomolecular complex, also called a biomacromolecular complex, is any biological complex made of more than one biopolymer (protein, RNA, DNA, [5] carbohydrate) or large non-polymeric biomolecules . The interactions between these biomolecules are non-covalent. [6] Examples: