DEFINITION: chemical changes are called chemical reactions
THEORY OF CHEMICAL REACTIONS: one set of substances is transformed into another set of substances. The substances that react are called reactants and the new ones products.
According to the collision theory, chemical reactions occur when the particles of the reactants collide with each other and are broken. But not all collisions break the molecules; it is only effective if the molecules collide in the right orientation and with sufficient speed to be able to break.
Increase the speed of a collision by.
-Increasing the temperature
-Splitting the substance into smaller pieces. They react faster because the contact surface is greater.
Law of conservation of mass or Lavoisier’s law:
IN 1772, Antoine-Laurent Lavoisier established this law. He said that in a chemical reaction, matter is neither created nor destroyed, only transformed, so the total mass is the same.