Kinetic Energy Challenges Molecular Attraction
Kinetic Energy Challenges Molecular Attraction is a Grade 7 science skill from Amplify Science California, Chapter 3: Investigating Attraction and Phase Change. Students learn how molecules exist in a constant competition between kinetic energy that drives them apart and molecular attraction that pulls them together, and that a phase change only occurs when a molecule's kinetic energy becomes strong enough to overcome the attraction.
Key Concepts
Molecules in a substance are in a constant tug of war. The kinetic energy of the molecules makes them move and spread apart. At the same time, a constant force of molecular attraction pulls the molecules back together.
This "competition" between movement and attraction determines if a substance will change phase. A phase change happens only when the molecules' movement becomes strong enough to overcome the attraction. If the attraction is still stronger, the substance remains in its current phase.
Common Questions
What determines if a substance will change phase?
Phase change depends on a competition between the kinetic energy of molecules (causing them to move apart) and molecular attraction (pulling them together). A phase change occurs only when kinetic energy overcomes the attraction.
What is molecular attraction?
Molecular attraction is a constant force that pulls molecules toward each other. Its strength varies by substance and determines at what temperature a substance will boil, freeze, or change state.
How does adding heat cause a phase change?
Adding heat increases the kinetic energy of molecules, making them move faster and with more force. When kinetic energy becomes strong enough to overcome the molecular attraction holding molecules together, a phase change occurs.
What textbook covers kinetic energy and phase change for Grade 7?
This topic is covered in Amplify Science California, Grade 7, Chapter 3: Investigating Attraction and Phase Change.