4. If the heat of reaction is written on the reactant side of a chemical equation, what does that indicate about the reaction?
• It is an exothermic reaction.
• The energy of the products is less than the energy of the reactants.
• The reaction will release that amount of heat to the surroundings.
• It requires heat for the reaction to occur.

answer; natural resources;

each  column  of the  table  is called a group. elements in a group share similar properties. groups are  read  from  top  to  bottom. metal. metalloid. nonmetal. solid. liquid. gas. fe. hg. o.  2. 3. 4. 5. 6. 7. 8. 9.  2. beryllium. 9.012. 4.  sodium. 22.990.  11. 3.  magnesium. 24.305.  12.  potassium. 39.098.  19. 4.  calcium. 40.078.  20. i guess  i