Reactions

Chemical reactions are processes in which atoms are rearranged into different combinations of molecules. As a basis for understanding this concept:

a.	Students know reactant atoms and molecules interact to form products with different chemical properties.
b.	Students know the idea of atoms explains the conservation of matter: In chemical reactions the number of atoms stays the same no matter how they are arranged, so their total mass stays the same.
c.	Students know chemical reactions usually liberate heat or absorb heat.
d.	Students know physical processes include freezing and boiling, in which a material changes form with no chemical reaction.
e.	Students know how to determine whether a solution is acidic, basic, or neutral.