Geographers organize into regions in order to study their similar characteristics.

climates

cities

cultures

areas

Here is a picture  of the net. its 4 squares in a row diagonal and on the third draw one square aove and under

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen