the Physics Education Technology Project
the National Science Foundation
This simulation helps learners visualize how molecules behave in solids, liquids, and gases. Add or remove heat and watch the motion of the molecules as they change phase. Push the pump and change the volume of matter in the closed container and watch the pressure gauge respond. More advanced students can compare the potential energy graphs for neon, argon, oxygen, and water -- which all have different interaction potential.
This item is part of a larger collection of simulations developed by the Physics Education Technology project (PhET).
Please note that this resource requires
Java Applet Plug-in.
Editor's Note:Editor's Note: This particular activity would be well paired with the PhET "Gas Properties" simulation, which goes into more depth to explore the behavior of gas molecules in a closed container. Together, the simulations promote understanding of gas laws, states of matter, phase change, and kinetic theory. See Related Materials for links to lesson plans developed by teachers to accompany "States of Matter" simulation.
gas laws, gas volume, molecular models, molecular structure, phase, phase change simulation, states of matter, states of matter simulation
Metadata instance created
July 18, 2011
by Caroline Hall
August 18, 2016
by Lyle Barbato
Last Update when Cataloged:
July 5, 2011
AAAS Benchmark Alignments (2008 Version)
4. The Physical Setting
4D. The Structure of Matter
6-8: 4D/M1a. All matter is made up of atoms, which are far too small to see directly through a microscope.
6-8: 4D/M2. Equal volumes of different materials usually have different masses.
6-8: 4D/M3cd. In solids, the atoms or molecules are closely locked in position and can only vibrate. In liquids, they have higher energy, are more loosely connected, and can slide past one another; some molecules may get enough energy to escape into a gas. In gases, the atoms or molecules have still more energy and are free of one another except during occasional collisions.
6-8: 4D/M7a. No matter how substances within a closed system interact with one another, or how they combine or break apart, the total mass of the system remains the same.
6-8: 4D/M8. Most substances can exist as a solid, liquid, or gas depending on temperature.
4E. Energy Transformations
6-8: 4E/M4. Energy appears in different forms and can be transformed within a system. Motion energy is associated with the speed of an object. Thermal energy is associated with the temperature of an object. Gravitational energy is associated with the height of an object above a reference point. Elastic energy is associated with the stretching or compressing of an elastic object. Chemical energy is associated with the composition of a substance. Electrical energy is associated with an electric current in a circuit. Light energy is associated with the frequency of electromagnetic waves.
9-12: 4E/H7. Thermal energy in a system is associated with the disordered motions of its atoms or molecules. Gravitational energy is associated with the separation of mutually attracting masses. Electrical potential energy is associated with the separation of mutually attracting or repelling charges.
9-12: 4E/H9. Many forms of energy can be considered to be either kinetic energy, which is the energy of motion, or potential energy, which depends on the separation between mutually attracting or repelling objects.
4G. Forces of Nature
9-12: 4G/H2a. Electric forces acting within and between atoms are vastly stronger than the gravitational forces acting between the atoms. At larger scales, gravitational forces accumulate to produce a large and noticeable effect, whereas electric forces tend to cancel each other out.
11. Common Themes
6-8: 11B/M1. Models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly. They are also used for processes that are too vast, too complex, or too dangerous to study.
6-8: 11B/M4. Simulations are often useful in modeling events and processes.
6-8: 11D/M3. Natural phenomena often involve sizes, durations, and speeds that are extremely small or extremely large. These phenomena may be difficult to appreciate because they involve magnitudes far outside human experience.
Next Generation Science Standards
Matter and Its Interactions (MS-PS1)
Students who demonstrate understanding can: (6-8)
Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed. (MS-PS1-4)
Students who demonstrate understanding can: (6-8)
Develop a model to describe that when the arrangement of objects interacting at a distance changes, different amounts of potential energy are stored in the system. (MS-PS3-2)
Students who demonstrate understanding can: (9-12)
Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as either motions of particles or energy stored in fields. (HS-PS3-2)
Plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system (second law of thermodynamics). (HS-PS3-4)
Disciplinary Core Ideas (K-12)
Structure and Properties of Matter (PS1.A)
Gases and liquids are made of molecules or inert atoms that are moving about relative to each other. (6-8)
In a liquid, the molecules are constantly in contact with others; in a gas, they are widely spaced except when they happen to collide. In a solid, atoms are closely spaced and may vibrate in position but do not change relative locations. (6-8)
Solids may be formed from molecules, or they may be extended structures with repeating subunits (6-8)
The changes of state that occur with variations in temperature or pressure can be described and predicted using these models of matter. (6-8)
Types of Interactions (PS2.B)
Attraction and repulsion between electric charges at the atomic scale explain the structure, properties, and transformations of matter, as well as the contact forces between material objects. (9-12)
Definitions of Energy (PS3.A)
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. (6-8)
Temperature is a measure of the average kinetic energy of particles of matter. The relationship between the temperature and the total energy of a system depends on the types, states, and amounts of matter present. (6-8)
Conservation of Energy and Energy Transfer (PS3.B)
The amount of energy transfer needed to change the temperature of a matter sample by a given amount depends on the nature of the matter, the size of the sample, and the environment. (6-8)
Relationship Between Energy and Forces (PS3.C)
When two objects interacting through a field change relative position, the energy stored in the field is changed. (9-12)
Crosscutting Concepts (K-12)
Cause and Effect (K-12)
Cause and effect relationships may be used to predict phenomena in natural systems. (6-8)
Cause and effect relationships can be suggested and predicted for complex natural and human designed systems by examining what is known about smaller scale mechanisms within the system. (9-12)
Scale, Proportion, and Quantity (3-12)
Phenomena that can be observed at one scale may not be observable at another scale. (6-8)
The significance of a phenomenon is dependent on the scale, proportion, and quantity at which it occurs. (9-12)
Systems and System Models (K-12)
Models can be used to represent systems and their interactions—such as inputs, processes and outputs— and energy, matter, and information flows within systems. (6-8)
When investigating or describing a system, the boundaries and initial conditions of the system need to be defined and their inputs and outputs analyzed and described using models. (9-12)
Structure and Function (K-12)
Complex and microscopic structures and systems can be visualized, modeled, and used to describe how their function depends on the shapes, composition, and relationships among its parts, therefore complex natural structures/systems can be analyzed to determine how they function. (6-8)
The functions and properties of natural and designed objects and systems can be inferred from their overall structure, the way their components are shaped and used, and the molecular substructures of its various materials. (9-12)
Stability and Change (2-12)
Explanations of stability and change in natural or designed systems can be constructed by examining the changes over time and forces at different scales. (6-8)
Much of science deals with constructing explanations of how things change and how they remain stable. (9-12)
Scientific Knowledge Assumes an Order and Consistency in Natural Systems (1-12)
Science assumes that objects and events in natural systems occur in consistent patterns that are understandable through measurement and observation. (6-8)
NGSS Science and Engineering Practices (K-12)
Analyzing and Interpreting Data (K-12)
Analyzing data in 6–8 builds on K–5 and progresses to extending quantitative analysis to investigations, distinguishing between correlation and causation, and basic statistical techniques of data and error analysis. (6-8)
Analyze and interpret data to provide evidence for phenomena. (6-8)
Analyzing data in 9–12 builds on K–8 and progresses to introducing more detailed statistical analysis, the comparison of data sets for consistency, and the use of models to generate and analyze data. (9-12)
Analyze data using computational models in order to make valid and reliable scientific claims. (9-12)
Developing and Using Models (K-12)
Modeling in 6–8 builds on K–5 and progresses to developing, using and revising models to describe, test, and predict more abstract phenomena and design systems. (6-8)
Develop a model to describe unobservable mechanisms. (6-8)
Modeling in 9–12 builds on K–8 and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds. (9-12)
Use a model based on evidence to illustrate the relationships between systems or between components of a system. (9-12)
This resource is part of 2 Physics Front Topical Units.
Topic: Particles and Interactions and the Standard Model Unit Title: Matter and Interactions
This simulation can help students visualize how molecules behave in solids, liquids, and gases. Add or remove heat and watch the motion of the molecules as they change phase. Push the pump and change the volume of matter in the closed container. More advanced students can compare the potential energy graphs for neon, argon, oxygen, and water (which all have different interaction potential).
Topic: Heat and Temperature Unit Title: Teaching about Heat and Thermal Energy
Great simulation to promote understanding of how molecules behave in solids, liquids, and gases. Add or remove heat and watch the motion of the molecules as they change phase. Push the pump and change the volume of matter in the closed container and watch the pressure gauge respond. More advanced students can compare the potential energy graphs for neon, argon, oxygen, and water -- which all have different interaction potential. For detailed Student Guide, see the item directly above.
National Science Foundation. PhET Simulation: States of Matter. Boulder: Physics Education Technology Project, July 5, 2011. https://phet.colorado.edu/en/simulation/states-of-matter (accessed 8 December 2016).
%0 Electronic Source %D July 5, 2011 %T PhET Simulation: States of Matter %I Physics Education Technology Project %V 2016 %N 8 December 2016 %8 July 5, 2011 %9 application/java %U https://phet.colorado.edu/en/simulation/states-of-matter
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