MS - PS3.A (A1 and B1) - Heat and Chemical Reactions - ASSIGNED (CLF 1/23/2014)

PS3.A (A1):  The term “heat” as used in everyday language refers both to thermal energy (the motion of atoms or molecules within a substance) and the transfer of that thermal energy from one object to another. In science, heat is used only for this second meaning; it refers to the energy transferred due to the temperature difference between two objects. (secondary to MS-PS1-4)

PS3.A (B1):  The temperature of a system is proportional to the average internal kinetic energy and potential energy per atom or molecule (whichever is the appropriate building block for the system’s material). The details of that relationship depend on the type of atom or molecule and the interactions among the atoms in the material. Temperature is not a direct measure of a system's total thermal energy. The total thermal energy (sometimes called the total internal energy) of a system depends jointly on the temperature, the total number of atoms in the system, and the state of the material. (secondary to MS-PS1-4)

[Clarification Statement: Emphasis is on qualitative molecular-level models of solids, liquids, and gases to show that adding or removing thermal energy increases or decreases kinetic energy of the particles until a change of state occurs. Examples of models could include drawing and diagrams. Examples of particles could include molecules or inert atoms. Examples of pure substances could include water, carbon dioxide, and helium.]

The ideas we see in this standard are: 

- heat refers to both thermal energy and the transfer of thermal energy from one object to another.  In science we should focus our attention on the second meaning, rather than the more colloquial meaning of the term. 

- temperature in a system is proportional to the average kinetic energy and potential energy per atom or molecule.  

- the details of the relationship between temperature and kinetic energy depend on the type of atom or molecule in the material. 

- temperature is not a direct measure of a system's total energy, total thermal energy depends on both temperature, the number of atoms, and the state of the material. 

This batch should focus only on the definitions of heat, thermal energy, kinetic energy, and temperature of a system - and how those properties may change as materials interact with each other.  This is a module that is will be taught with chemistry, so that provides some frame of reference. We should be thinking about changes that happen to the average kinetic energy, temperature, etc of a substance when it undergoes a chemical reaction. We can use endothermic and exothermic reactions, for example.