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Solid-phase electrical conductivity: Variable, [6] depending on the nature of the bonding: network solids in which all electrons are used for sigma bonds (e.g. diamond, quartz) are poor conductors, as there are no delocalized electrons. However, network solids with delocalized pi bonds (e.g. graphite) or dopants can exhibit metal-like conductivity.
Solids can be classified according to the nature of the bonding between their atomic or molecular components. The traditional classification distinguishes four kinds of bonding: [1] Covalent bonding, which forms network covalent solids (sometimes called simply "covalent solids") Ionic bonding, which forms ionic solids
Molecular solids have low melting (T m) and boiling (T b) points compared to metal (iron), ionic (sodium chloride), and covalent solids (diamond). [ 4 ] [ 5 ] [ 8 ] [ 13 ] Examples of molecular solids with low melting and boiling temperatures include argon , water , naphthalene , nicotine , and caffeine (see table below).
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Such covalent substances are low-boiling-temperature liquids (such as ethanol), and low-melting-temperature solids (such as iodine and solid CO 2). Macromolecular structures have large numbers of atoms linked by covalent bonds in chains, including synthetic polymers such as polyethylene and nylon , and biopolymers such as proteins and starch .
In chemistry, a formula unit is the smallest unit of a non-molecular substance, such as an ionic compound, covalent network solid, or metal. [1] [2] It can also refer to the chemical formula for that unit. Those structures do not consist of discrete molecules, and so for them, the term formula unit is used.
The titanium atoms 6-coordinate, 2 atoms at 198.3 pm and 4 at 194.6 pm, in a slightly distorted octahedron. The octahedra around the titanium atoms share edges and vertices to form a 3-D network. The oxide ions are 3-coordinate in a trigonal planar configuration. [17]
However, structural determinations of vitreous SiO 2 and GeO 2 made by Warren and co-workers in the 1930s using x-ray diffraction showed the structure of glass to be typical of an amorphous solid [7] In 1932, Zachariasen introduced the random network theory of glass in which the nature of bonding in the glass is the same as in the crystal but ...