Why is the total mass always conserved in a chemical reaction? be sure that your explanation includes the discussion of atoms and bonds.

The total mass is always conserved in a chemical reaction because mass cannot be destroyed nor created. This is expressed in the law of conservation of mass. Atoms in a reaction cannot form another type of  atoms which has different properties than the original element. It can only exchange electrons which is responsible for bonding.

Depending on how the continental plates move it can cause a continental scale shift.