Which element reacts with oxygen to form ionic bonds?

Most metals actually. 
Pick one. For example K forms K2O. MgO, Fe2O3, etc...
Metals will lose electrons, oxygen will gain to form the bond

Metals in general would actually have the need to form an ionic bond with oxygen to form a full octet. 

Idon't know hope someone you

Vander waals forces are inter molecular bonds that exist within molecules of the same substance. a water molecule is made up of oxygen and hydrogen atoms which share electrons between each other. the vander waals forces are forces that exist between multitude of different  molecules of water. dipole dipole forces is the type of vander waals force that exist in water. the oxygen atom which is more electronegative pulls the shared electron closer to itself thus generating a partial negative charge while the hydrogen acquire a partial positive charge. these two different charges causes attraction to occur in water molecules.