CHEMICAL BONDING AND COMPOUND FORMATIONOne of the most important requirements in chemistry is to become familiar with the ways in which elements react to form compounds. We will investigate the types of chemical bonds, ways to predict compositions and the conventions of naming the compounds. Chemical bonds make atoms more stable than they are if non-bonded Bond formation involves changes in the electrons on two atoms This is achieved by one of two methods Electron transfer Electron sharingElectron transfer involves creation ofions, which bond viaionicbonds to form ionic compounds. A Familiar compound like table salt, sodium chloride, is a classic example of an ionic compound.The documents called Type 1 Compounds and Type 2 Compounds give information on predicting composition and naming of ionic compounds[1]Electron sharing involves the sharing of electrons between two atoms and the creation ofcovalentbonds. Covalently bonded compounds typically have very different properties from ionic compounds, and they also involve combinations of different types of elements.The document called Type 3 Compounds gives information of the naming of covalent compounds.[2]Although there are many elements and even more compounds to consider, familiarity with a few rules will greatly simplify the process of becoming conversant with determining compositions of compounds.The octet ruleIt is well known that the elements in group 8, the noble gases, are extremelyunreactive. Examination of the electronic structures of these elements shows that the outer shells are full of electrons; they do not lack for electrons to fill the shells. None of the other elements has a filled outer shell.The inference we draw from this is that the atom wants to obtain a filled shell, and this it achieves by forming bonds. This can be done by either addition of electrons or removal of electrons. The noble gas atom already has a filled shell and does not need to indulge in bonding to achieve it.

Elements on the left side of the table, metals, will lose electrons to form positive ions; elements on the right hand side of the table, non-metals, will gain electrons. In both cases, a filled shell will result.Of course, we must recognize that the atom is now charged because the electron and proton counts are not equal. Electron loss creates positive ions, and electron gain creates negative ions.In an ionic compound, a positive ion and a negative ion come together and form an ionic bond through the strong electrostatic interaction between the ions of opposing charge.