🔍 Key Concepts

• Difference between heat (energy in transit) and internal energy (energy stored in a substance) • How molecular motion (kinetic energy) and molecular arrangement/bonds (potential energy) contribute to energy inside a substance • What happens to molecules when a substance is heated but does NOT change temperature versus when it DOES change temperature

💭 Think About

• Ask yourself: is the question about energy while it is being transferred, or about how it is stored after it has been added? • Think about the microscopic level: when you add thermal energy, what actually changes inside the substance’s molecules and their motion? • Which answer choice describes the total energy contained within all the molecules of a substance, not just the energy crossing the boundary as heat?

✅ Before You Answer

• Verify which term describes the energy transfer process and which term describes energy already contained in the substance • Eliminate any answers that are just other forms of energy not specifically defined as the stored thermal content of a substance • Make sure the correct choice refers to the sum of microscopic kinetic and potential energies of the molecules