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A network solid or covalent network solid (also called atomic crystalline solids or giant covalent structures) [1][2] is a chemical compound (or element) in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material. In a network solid there are no individual molecules, and the entire crystal or ...
Network covalent structures (or giant covalent structures) contain large numbers of atoms linked in sheets (such as graphite), or 3-dimensional structures (such as diamond and quartz). These substances have high melting and boiling points, are frequently brittle, and tend to have high electrical resistivity.
A macromolecule is a very large molecule important to biological processes, such as a protein or nucleic acid. It is composed of thousands of covalently bonded atoms. Many macromolecules are polymers of smaller molecules called monomers. The most common macromolecules in biochemistry are biopolymers (nucleic acids, proteins, and carbohydrates ...
Silicon crystallises in a giant covalent structure at standard conditions, specifically in a diamond cubic crystal lattice (space group 227). It thus has a high melting point of 1414 °C, as a lot of energy is required to break the strong covalent bonds and melt the solid.
The most stable crystalline form is the hexagonal one, also called h-BN, α-BN, g-BN, and graphitic boron nitride. Hexagonal boron nitride (point group = D 3h; space group = P6 3 /mmc) has a layered structure similar to graphite. Within each layer, boron and nitrogen atoms are bound by strong covalent bonds, whereas the layers are held together ...
Dynamic covalent chemistry. Dynamic covalent chemistry (DCvC) is a synthetic strategy employed by chemists to make complex molecular and supramolecular assemblies from discrete molecular building blocks. [1] DCvC has allowed access to complex assemblies such as covalent organic frameworks, molecular knots, polymers, and novel macrocycles. [2]
A fullerene is an allotrope of carbon whose molecules consist of carbon atoms connected by single and double bonds so as to form a closed or partially closed mesh, with fused rings of five to seven atoms. The molecules may have hollow sphere - and ellipsoid -like forms, tubes, or other shapes. Fullerenes with a closed mesh topology are ...
In the diamond-like structure, called cubic boron nitride (tradename Borazon), boron atoms exist in the tetrahedral structure of carbon atoms in diamond, but one in every four B-N bonds can be viewed as a coordinate covalent bond, wherein two electrons are donated by the nitrogen atom which acts as the Lewis base to a bond to the Lewis acidic ...