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A silicon–oxygen bond (Si−O bond) is a chemical bond between silicon and oxygen atoms that can be found in many inorganic and organic compounds. [1] In a silicon–oxygen bond, electrons are shared unequally between the two atoms , with oxygen taking the larger share due to its greater electronegativity .
The type of bonding can be explained in terms of orbital hybridisation. In ethylene each carbon atom has three sp 2 orbitals and one p-orbital. The three sp 2 orbitals lie in a plane with ~120° angles. The p-orbital is perpendicular to this plane. When the carbon atoms approach each other, two of the sp 2 orbitals overlap to form a sigma bond.
The C–Si bond is somewhat polarised towards carbon due to carbon's greater electronegativity (C 2.55 vs Si 1.90), and single bonds from Si to electronegative elements are very strong. [14] Silicon is thus susceptible to nucleophilic attack by O − , Cl − , or F − ; the energy of an Si–O bond in particular is strikingly high.
Moreover, the multiple bonds of the elements with n=2 are much stronger than usual, because lone pair repulsion weakens their sigma bonding but not their pi bonding. [2] An example is the rapid polymerization that occurs upon condensation of disulfur, the heavy analogue of O 2. Numerous exceptions to the rule exist. [3]
Polycarbonate is commonly used in eye protection, as well as in other projectile-resistant viewing and lighting applications that would normally indicate the use of glass, but require much higher impact-resistance. Polycarbonate lenses also protect the eye from UV light.
In 1916, chemist Gilbert N. Lewis developed the concept of electron-pair bonds, in which two atoms may share one to six electrons, thus forming the single electron bond, a single bond, a double bond, or a triple bond; in Lewis's own words, "An electron may form a part of the shell of two different atoms and cannot be said to belong to either ...
A polycarbonate is an oxocarbon dianion consisting of a chain of carbonate units, where successive carbonyl groups are directly linked to each other by shared additional oxygen atoms. That is, they are the conjugate bases of polycarbonic acids , the conceptual anhydrides of carbonic acid , or polymers of carbon dioxide .
Covalent and ionic bonding form a continuum, with ionic character increasing with increasing difference in the electronegativity of the participating atoms. Covalent bonding corresponds to sharing of a pair of electrons between two atoms of essentially equal electronegativity (for example, C–C and C–H bonds in aliphatic hydrocarbons).