Chemical BondsA series of free High School Chemistry Video Lessons from Brightstorm.
Ionic Bond In an ionic bond, two ions are held together by electrostatic force. These two atoms are trying to attain full valence shells of eight electrons. One atom has too many electrons and another has too few so one atom donates electrons and the other accepts them. The donor atom forms a cation, or positively charged ion and the other forms an anion, a negatively charged ion. The two are held together by the electrostatic attraction between opposite charges.
Ionic Compound Properties Ionic compound properties stem from their structure. Ionic compounds are found in lattice structures, making them extremely brittle. Ionic compounds have high melting points and form electrolytic solutions, which conduct electricity. Covalent compounds, on the other hand, are comparitively soft and round, have relativley low melting and boiling points and form non-electrolytic solutions.
Metallic Bond A metallic bond shares electrons but unlike ionic bonds, it does not fill the valence shell octets of the bonding atoms. All of the electrons involved form one huge electron cloud which all the nuclei share. The attraction of the nuclei to the electrons keeps them together. Metallic solids are very conductive because of this electron cloud and are malleable.
Covalent Bond Molecules are bound by covalent bonds in which two atoms with unfilled valence shells share electrons so that they each have a full octet. If one atom is more electronegative than the other, it holds onto the shared electrons more tightly, pulling the negatively charged electron cloud towards itself and resulting in an imbalance of charges called polarity. If a single covalent bond isn’t enough for two atoms to fill their octets, they may share two or more pairs of electrons.
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