Solvation is the attraction and association of molecules of a solvent with molecules or ions of a solute. As ions dissolve in a polar solvent they spread out and become surrounded by solvent molecules. The bigger the ion, the more solvent molecules are able to surround it and the more it becomes hydrated. Similarly, the higher the charge on the ion the more solvent molecules it attracts. Solvent molecules have the effect of pulling apart the electron clouds that surround an ion's nucleus, and the higher the charge and the smaller the ion (these factors combined are known as charge density) then the larger an ion becomes when dissolved. A molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ... A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ... An ion is an atom or group of atoms with a net electric charge. ... A substance is soluble in a fluid if it dissolves in the fluid. ... A commonly-used example of a polar compound is water (H2O). ... Hydrates are compounds formed by the union of water with some other substance, generally forming a neutral body, as certain crystallized salts. ... Charge is a word with many different meanings. ... Electron cloud is a term used for introducing the concept of wavefunction in low-level pedagogical introductions to atomic physics, molecular physics, chemistry or quantum chemistry. ... A stylized representation of a lithium atom. ... Charge density is the amount of electric charge per unit volume. ...

Solvation occurs by lewis acid & lewis base interactions. In chemistry, a Lewis acid can accept a pair of electrons and form a coordinate covalent bond, after the American chemist Gilbert Lewis. ... A Lewis base is any molecule or ion that can form a new covalent bond by donating a pair of electrons. ...

For solvation to occur, energy is required to release individual ions from the ionic lattices in which they are present. This is necessary to break the attractions the ions have with each other and is equal to the solid's lattice enthalpy (the energy released at the formation of the lattice as the ions bonded with each other.) The energy for this comes from the energy released when ions of the lattice associate with molecules of the solvent. Energy released in this form is called the enthalpy of solvation (or with water as the solvent, the enthalpy of hydration.) Again, the amount of energy released depends on the degree of attraction and the number of solvent molecules the ion associates with, and thus increases with charge density. The ordinary meaning of lattice is the basis for several technical usages A cherry lattice pastry A mathematical lattice that is a type of partially ordered set. ... In jewelry, a solid gold piece is the alternative to gold-filled or gold-plated jewelry. ... Enthalpy (symbolized H, also called heat content) is the sum of the internal energy of matter and the product of its volume multiplied by the pressure. ... Water (from the Old English word wæter; c. ...

Enthalpy of solvation can help explain why solvation occurs with some ionic lattices but not with others. The difference in energy between that which is necessary to release an ion from its lattice and the energy given off when it combines with a solvent molecule is called the enthalpy change of solution. A negative value for the enthalpy change of solution corresponds to an ion that is likely to dissolve, whereas a high positive value means that solvation will not occur. It is possible that an ion will dissolve even if it has a positive enthalpy value. The extra energy required comes from the increase in entropy that results when the ion dissolves. The introduction of entropy makes it harder to determine by calculation alone whether a substance will dissolve or not. A quantitative measure for solvation power of solvents is given by donor numbers. The enthalpy change of solution is the quantity of heat produced or absorbed when a one mole of a substance is dissolved in a large volume of a solvent at constant pressure. ... A negative number is a number that is less than zero, such as −3. ... A negative number is a number that is less than zero, such as −3. ... For other senses of the term entropy, see entropy (disambiguation). ... In chemistry a donor number or DN is a qualitative measure of lewis basicity. ...

See also

• Solute
• Solution
• Solvent

A substance is soluble in a fluid if it dissolves in the fluid. ... Dissolving table salt in water In chemistry, a solution is a homogeneous mixture of one or more substances (the solutes) dissolved in another substance (the solvent). ... A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ...

References

• "The Chemical Physics of Solvation". Edited by R.R. Dogonadze, E. Kalman, A.A. Kornyshev and J. Ulstrup, I-III, Elsevier, Amsterdam, 1985-1987