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Module 1 Intro

1. Module 1 Intro

1.27. Page 5

Module 1: Lesson 5

Module 1—Chemical Foundations

Lesson Summary

 

Reflect on the critical questions asked at the beginning of this lesson:

  • What is the particle model of matter?

  • What is the kinetic molecular theory?

  • What are the types of changes in matter, and what evidence is there that a chemical change has occurred?

In this lesson you compared and contrasted physical changes, chemical changes, and nuclear changes.

  • Phase changes involve the rearrangement of particles that affect the bonds between particles (intermolecular bonds). These changes are characterized by having relatively small energy changes and no new substances formed.

  • Chemical changes involve the rearrangement of particles that affect the bonds within a particle (intramolecular bonds). Chemical changes are characterized by having larger energy changes and the formation of new substances with new properties.

  • Nuclear changes involve the rearrangement of sub-atomic particles within an atom (nuclear bonds). These changes are characterized by having massive energy changes, the formation of new elements, and the release of radiation.

You took a brief look at the kinetic molecular theory, which states that the tiny entities within any substance are constantly in random motion. This led you to the study of the collision-reaction theory in which the motion of entities results in collisions and the possibility of new substances forming in a chemical reaction. You reviewed the law of conservation of mass, which states that the total mass present before a chemical change is equal to the total mass present after a chemical change.

 

Lesson Glossary

 

endothermic process: a change in matter that requires an input of energy to occur

 

exothermic process: a change in matter that releases energy when it occurs

 

intermolecular: existing or acting between molecules

 

nuclear change: a process that causes an alteration to the composition of an atom’s nucleus

 

physical change: a change in the form of a substance in which its chemical composition is unchanged