Many salts dissolve when immersed in water. All nitrates, perchlorates and acetates are water soluble, as are most chlorides, bromides, iodides and sulfates, according to "Fundamentals of General, Organic, and Biological Chemistry" by John McMurry, et al. Metals, such as sodium and potassium, form salts that are more soluble than those with other metal components.
Such salts as sodium chloride are ionic compounds in which positive and negative ions unite with each other by means of electrostatic forces. However, water exerts electrostatic forces of it own. It is a polar molecule in which one end is electropositive and the other end is electronegative. When sodium chloride becomes immersed in water, the positive end of the water molecule attracts the negative chlorine ions, and the negative end attracts the positive sodium ions. This electrostatic action of water pulls the sodium and chloride ions away from each other and the solid salt consequently dissolves. In some ionic compounds, such as calcium carbonate, the bond between the salt ions is so strong that the water molecules cannot pull the ions apart, so calcium carbonate is insoluble in water.
In dry state, some bases and acids, such as sodium hydroxide, capric acid and acetic acid, are solids at room temperature or slightly below. Both sodium hydroxide and acetic acid dissolve in water, as do most acids and bases. However, capric acid is not water soluble.
Another type of solid does not form ions. Instead, its atoms form molecules by uniting with one another in chemical unions called covalent bonds. Many solid covalent compounds, such as the components of human skin, do not dissolve in water, but others, such as glucose and table sugar, have polar molecules with a positive and negative end, just like water. Glucose and table sugar dissolve in water because the electrical attraction between the polar water and sugar molecules overcomes the coherent force by which the sugar molecules cling to one another.
Some solids that are neither ionic nor polar may still exhibit slight water solubility. Iodine serves as an example. It is a solid at room temperature. Though a covalent compound with no polarity, some of iodine dissolves in water.