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Bonds with partially ionic and partially covalent characters are called polar covalent bonds. [2] Ionic compounds conduct electricity when molten or in solution, typically not when solid. Ionic compounds generally have a high melting point, depending on the charge of the ions they consist of. The higher the charges the stronger the cohesive ...
Electrons in an ionic bond tend to be mostly found around one of the two constituent atoms due to the large electronegativity difference between the two atoms, generally more than 1.9, (greater difference in electronegativity results in a stronger bond); this is often described as one atom giving electrons to the other. [5]
Ionic bonds are strong (and thus ionic substances require high temperatures to melt) but also brittle, since the forces between ions are short-range and do not easily bridge cracks and fractures. This type of bond gives rise to the physical characteristics of crystals of classic mineral salts, such as table salt.
Conversely, when an ionic liquid is cooled, it often forms an ionic solid—which may be either crystalline or glassy. The ionic bond is usually stronger than the Van der Waals forces between the molecules of ordinary liquids. Because of these strong interactions, salts tend to have high lattice energies, manifested in
Silicon–oxygen single bonds are longer (1.6 vs 1.4 Å) but stronger (452 vs. about 360 kJ mol −1) than carbon–oxygen single bonds. [1] However, silicon–oxygen double bonds are weaker than carbon–oxygen double bonds (590 vs. 715 kJ mol −1) due to a better overlap of p orbitals forming a stronger pi bond in the latter.
Hydrogen bonds contribute to the stability of ion pairs with e.g. protonated ammonium ions, and with anions is formed by deprotonation as in the case of carboxylate, phosphate etc; then the association constants depend on the pH. Entropic driving forces for ion pairing (in absence of significant H-bonding contributions) are also found in ...
Ionic bonds generally occur when the difference in electronegativity between the two atoms is greater than 2.0; Pauling based this classification scheme on the partial ionic character of a bond, which is an approximate function of the difference in electronegativity between the two bonded atoms. He estimated that a difference of 1.7 corresponds ...
For ionic compounds made of molecular cations and/or anions, there may also be ion-dipole and dipole-dipole interactions if either molecule has a molecular dipole moment. The theoretical treatments described below are focused on compounds made of atomic cations and anions, and neglect contributions to the internal energy of the lattice from ...