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Introduction
Introduction
Every substance in the universe is made up of matter. A substance can exist in three different states: solid, liquid, or gas. A substance such as water can easily transition from one state of matter to the other. For example, water transitions from a solid state to a liquid state when an ice cube melts (Figure - Left). The ice cube is able to melt and transition from a solid to a liquid because it absorbs thermal energy. Thermal energy is a type of energy that is transferred between two objects because they have different temperatures. In the example of an ice cube melting, thermal energy is transferred to the ice cube from the warm air surrounding it. Thermal energy always moves from the warmer object to the colder object. Think about another example, such as a cold can of soda in your hand. In that case, thermal energy is transferring from your hand to the soda; eventually the cold soda will gain enough thermal energy that it becomes the same temperature as its surroundings.
States of Matter
States of Matter
All substances, regardless of whether they are a solid, a liquid, or a gas, are made up of atoms and molecules. Atoms and molecules are submicroscopic, meaning they are too small to be seen with our eyes and even too small to be seen with most microscopes. The atoms or molecules that make up a substance are constantly in motion. The composition of a substance will always be the same even though the substance can transition from one state to a different state. Water, for example, is always made of H20 molecules even when it is in a solid (ice), liquid, or gaseous (steam) state.
The difference between the solid, liquid, and gas states of a substance is due to the amount of kinetic energy the atoms or molecules have and how these particles are moving relative to each other. Kinetic energy is the energy of motion. Atoms or molecules that are moving quickly have more kinetic energy than atoms or molecules that move more slowly. For example, the molecules found within a sample of gaseous water move around quickly. These molecules therefore have a lot of kinetic energy. The molecules that are found in a sample of solid water, in contrast, move around slower and have less kinetic energy than the molecules in a sample of gaseous water. You can therefore measure the temperature of a substance to learn about the average kinetic energy of the molecules within that substance.
Matter and Energy
Matter and Energy
At this point, we have established several key ideas about the nature of matter. For example, we know that all matter can exist in three different states and all matter is composed of atoms or molecules that are really small. We also know that a substance has the same composition regardless of its state and that the atoms or molecule of a substance will have different amounts of kinetic energy at different temperatures. These ideas, when taken together, can serve as a foundation for the development of an explanatory model that can be used to illustrate what happens at the molecular level when thermal energy is added to a substance. This type of model is important to develop because explanatory models can help us predict the behavior of matter under different conditions. For example, we could use an explanatory model to help us predict which state a substance would be in or how long it will take a substance to boil when it is heated on a hot plate or a stove.
Your goal for this introductory investigation will be to develop an answer using the simulator. Play with the simulator and begin to understand the controls. Click all of the buttons and observe how the matter in the simulator changes. Use the simulator to help you develop a claim, collect evidence, and produce reasoning to to question below.
Your goal for this introductory investigation will be to develop an answer using the simulator. Play with the simulator and begin to understand the controls. Click all of the buttons and observe how the matter in the simulator changes. Use the simulator to help you develop a claim, collect evidence, and produce reasoning to to question below.
What happens at the molecular level when thermal energy is added to a substance?
What happens at the molecular level when thermal energy is added to a substance?
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