CHEMGEN Lecture 4: COMPOUND FORMATION, FORMULAS AND CALCULATIONS INVOLVING THE FORMULA

• School: Technological University of the Philippines
• Department: Chemistry
• Course: CHEMGEN

Document Summary

A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. Ionic substances are formed when an atom that loses electrons relatively easily react with an atom that has a high affinity for electrons. are formed by the attraction of oppositely charged ions. The formation of ionic bonds is always exothermic. Atoms share pairs of electrons to attain octets. Molecules generally weakly attracted to each other. Remember that the charge of an ion can be determined by its place on the periodic table. A simplified method of writing formulas of ionic compounds is the crisscross method. The symbol of the positive ion is written 1st followed by the negative ion. If the subscript is 1 it is not written. Criss cross i. e, the valance of the positive ion becomes the subscript of the negative ion, while the valence of the negative ion becomes the subscript of the positive ion.