Ionic, Covalent, and Metallic Bonds

Almost all the atoms on and off earth are found in groups with other atoms. But how do they join together? There isn't any atomic stapled or nuclide glue. The atoms join together to form compounds with bonds. The three types of bonds are ionic, covalent, and metallic, and each bond yields fairly predictable characteristics in the molecules that they form.

Ionic Bonds

Definition: Chemical bonding that results from the electrical attraction between cations and anions.

Ionic bonds are formed between a metal and a nonmetal. The electrons in compounds with these bonds are transferred from the cation to the anion. The difference between the anion's and cation's electronegativity is between 1.7 and 3.3. Any two atoms with a difference in electronegativities of 3.3 have fully ionic bonds, while two atoms with a difference of 1.7 share half ionic bonds. Compounds with ionic bonds appear to be powdery or make granules, dissolve in water, do not melt easily, and conduct electricity while melted and dissolved in water, but not as a solid. Some examples of compounds with ionic bonds are NaCl and NaBr.

Covalent Bonds

Definition: A bond that results from the sharing of electron pairs between two atoms

Covalent bonds are formed between two nonmetal atoms. The electrons are shared equally between the two atoms. The difference between the electronegativities of the two atoms is between 0 to 1.7. Any two atoms with a difference in electronegativities of 0 to 0.3 have fully to mostly non polar- covalent bonds, while any two atoms with a difference in electronegativities between 0.3 to 1.7 share mostly polar-covalent bonds. In nonpolar- covalent bonds, the electrons are shared equally. In polar-covalent bonds, electrons are shared unequally. Molecules that have covalent bonds usually appear to be powdery or granular, may dissolve in water, melt, and will not conduct electricity as a solid, liquid, or dissolved in deionized water. Some examples of compounds with ionic bonds are H2 and O2.

Metallic Bonds

Definition: The chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons.

Metallic bonds are formed between two metal atoms. The electrons move freely across atoms. In most metals, the orbitals in the metal's outermost energy levels overlap. Molecules that have metallic bonds appear to be shiny, are not soluble, do not melt easily, and will conduct electricity as a solid and as a liquid. Most metals are malleable, which means they have the ability to be flattened out into a thin sheet, and ductile, which means they have the ability to be drawn into a wire. some examples of metallic bonds can be found in copper wires and iron bars.

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