Atoms bond chemically to form molecules.
                        Types of bonding
                          The periodic table is organized in columns, called groups or  families, and rows, called periods.   There are several groups or periods that have specific names. 
                        
                          
                            
                              
                                | Bond type  | 
                                Happens between  | 
                                Electrons are  | 
                              
                              
                                Ionic  | 
                                Metal & non-metal  | 
                                Transferred  | 
                              
                              
                                Covalent  | 
                                Non-metals  | 
                                Shared  | 
                              
                              
                                Polar Covalent  | 
                                Non-metals  | 
                                Shared unevenly  | 
                              
                              
                                Metallic  | 
                                Metals  | 
                                pooled  | 
                              
                                                      
                           
                          There are general  characteristics of each type of bonding:
                          
                            
                              - Ionic: High melting points, most dissolve in water, conduct electricity when dissolved  in water, brittle
 
                              - Covalent: Low melting points, most do not dissolve in water, do not conduct electricity  when dissolved in water
 
                              - Polar  covalent: Medium melting points, some dissolve in water, do not conduct  electricity when dissolved in water
 
                              - Metallic:  Soft, conduct heat and electricity, do not  dissolve in water
 
                            
                           
                          Bond Polarity
  When nonmetals bond covalently with a large difference in  electronegativity, a polar bond is formed.   A polar bond has a partial separation of charges.  Polar bonds are symbolized with an arrow  pointing towards the more electronegative element and a crossed tail by the  less electronegative element
                        Isomers and Resonance
                          Isomers are compounds with the same chemical formula but  different chemical structure.  Resonance  occurs when a double bond can be placed in more than one place in a structure  without creating isomers.
                        Bonding theory
                          The Valence Shell Bonding Theory assumes that bonds are  formed when atomic orbitals overlap.   Direct overlap leads to sigma bonds and parallel overlap leads to pi  bond.  The Hybridization Theory says that the sigma bonds are all identical around an atom, therefore the  orbitals forming them must be identical.   Therefore, any atomic orbitals involved in sigma bonds hybridize into  identical orbitals to bond.  The Molecular  Orbital Theory says that rather than overlapping atomic orbitals, or  hybridized atomic orbitals, new orbitals are formed in the molecule that are  separate.  Some of the new orbitals  formed pull the two nuclei together and are bonding orbitals.  However, some of them pull the two orbitals  apart and are anti-bonding orbitals.  The  bond order is the number of bonding orbital electrons – the number of  antibonding orbital electrons divided by 2.   The bond order can be used to determine the type of bond (single,  double, triple).