Arrange the molecules and ions in each set in order of increasing acidity (from

CHEM 220: Organic Chemistry  Lewis Structures o Lewis structures help keep track of valence electrons of atoms and provide an easier understanding of reaction mechanisms. o Illustrates the transfer of electrons between atoms. o Helps calculate formal charge of an atom.  Rules for Lewis Structures o First, determine the number of valence electrons for an atom and arrange them so there is one on each side before adding more. o Second, arrange the atoms to form bonds with each of the electrons, for something like CH 4ine up Hydrogen’s electrons with each of the valence electrons of carbons. It might be helpful to draw bond lines at this point (optional.)  Formal Charge o Formal charge describes the relative charge of an atom in a molecule. o Highlights the polar ends, if any, of a molecule. o F.C.=(# of valence electrons)–½(# unshared electrons)-(# of bonds)  Resonance o Resonance involves the transfer of electrons across chemical structures and shows the most stable form of a molecule. o Since some molecules have either a positive or negative charge, different structures can be drawn that show the distribution of that charge across a molecule. This includes the moving of double bonds.  Think of (CO 3 and how you can move the electrons to form a double bond with each oxygen atom or benzene, where you can move the double bond