I.+Properties+of+Ionic+and+Covalent+Bonds


 * Comparison of Properties of Ionic and Covalent Compounds**
 * Because of the nature of [|ionic] and [|covalent] bonds, the materials produced by those bonds tend to have quite different macroscopic properties. The atoms of covalent materials are bound tightly to each other in stable molecules, but those molecules are generally not very strongly attracted to other molecules in the material. On the other hand, the atoms (ions) in ionic materials show strong attractions to other ions in their vicinity. This generally leads to low melting points for covalent solids, and high melting points for ionic solids. For example, the molecule carbon tetrachloride is a non-polar covalent molecule, CCl4. Its melting point is -23°C. By contrast, the ionic solid NaCl has a melting point of 800°C.**

1. Crystalline solids (made of ions) 2. High melting and boiling points 3. Conduct electricity when melted 4. Many soluble in water but not in nonpolar liquid || 1. Gases, liquids, or solids (made of molecules) 2. Low melting and boiling points 3. Poor electrical conductors in all phases 4. Many soluble in nonpolar liquids but not in water ||
 * **Ionic Compounds**
 * **Covalent Compounds**
 * You can anticipate some things about bonds from the positions of the constituents in the [|periodic table]. Elements from opposite ends of the periodic table will generally form ionic bonds. They will have large differences in [|electronegativity] and will usually form positive and negative ions. The elements with the largest electronegativities are in the upper right of the periodic table, and the elements with the smallest electronegativities are on the bottom left. If these extremes are combined, such as in RbF, the [|dissociation energy] is large. As can be seen from the illustration below, hydrogen is the exception to that rule, forming covalent bonds.**
 * You can anticipate some things about bonds from the positions of the constituents in the [|periodic table]. Elements from opposite ends of the periodic table will generally form ionic bonds. They will have large differences in [|electronegativity] and will usually form positive and negative ions. The elements with the largest electronegativities are in the upper right of the periodic table, and the elements with the smallest electronegativities are on the bottom left. If these extremes are combined, such as in RbF, the [|dissociation energy] is large. As can be seen from the illustration below, hydrogen is the exception to that rule, forming covalent bonds.**


 * Elements which are close together in electronegativity tend to form covalent bonds and can exist as stable free molecules. Carbon dioxide is a common example.**


 * || Structure || State || Forces between molecules || Melting and boiling points || Solubility in water || Conducts electricity? || Examples ||
 * Covalent || Molecular || Liquids and Gases || Weak || Low || Insoluble exceptions include HCl, Sugar, NH3 || No || H2O, O2, CH4 ||
 * Ionic || Giant lattice || Solids || Strong || High || Soluble || When molten (melted) and when dissolved in water. || CaO, NaCl, MgO ||

By: Sam Lee