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A network solid or covalent network solid is a chemical compound (or element) in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material.
A covalent bond is a type of chemical bonding which is formed as a result of sharing electron pairs between non-metal atoms. This electron sharing is occurred due to low electronegativity difference between the two atoms involved in bonding. In covalent bonding, non-metal atoms are typically involved.