Changing States of Matter
Target
I can define what matter is and identify the properties of each state it can be found in.
What is freezing?
What is evaporation?
Freezing
Freezing is the process of a liquid turning into a solid. It happens when the molecules (tiny particles) that make up a liquid slow down and stop moving past each other. The molecules rearrange themselves into a rigid structure as they get closer together. This rigid structure is what makes a solid.
For freezing to happen, a liquid usually needs to be cooled down. As the liquid gets colder, its molecules move more slowly. At some point, the molecular motion slows down so much that the molecules can't move past each other anymore. The temperature at which this happens is called the freezing point.
Water is a common example of freezing. The molecules in liquid water are constantly bouncing around and sliding past each other. When water is cooled to 0°C (32°F), the water molecules slow down and arranging themselves in a rigid crystalline structure known as ice.
Melting
Melting is when a solid turns into a liquid. Solids are materials where the molecules are packed tightly together in an organized structure. When you add heat energy to a solid, the molecules start vibrating and moving around more. As the solid absorbs more heat energy, the molecular vibrations increase until the organized structure of the solid breaks apart. The molecules are now free to move around and slide past each other. This is when the solid has melted into a liquid state.
The melting point is the specific temperature where a solid begins the melting process and turns into a liquid. Different materials have different melting points - for example, ice melts at 0°C or 32°F.
Evaporation
Evaporation is the process by which a liquid turns into a gas or vapor. For example, when water in a puddle or a wet sidewalk dries up, it is evaporating and turning into water vapor. This happens because of heat energy.
Molecules in liquids are always moving around and bumping into each other. When a liquid is exposed to heat or air movement, some molecules near the surface get enough energy to break away from the liquid and turn into a gas. These molecules drift off into the air as water vapor. This process of molecules escaping from the liquid phase into the gas phase is called evaporation.
The rate of evaporation depends on temperature - the hotter it is, the faster the liquid will evaporate. This is because at higher temperatures, liquid molecules have more energy and can more easily break away from the liquid's surface.
Condensation
Condensation is when a gas turns into a liquid. It happens when a gas like water vapor in the air gets cooled down and changes phase from a gas to a liquid.
For condensation to happen, the air needs to be humid, meaning there is a lot of water vapor mixed in with the air. If the humid air cools down enough, the water vapor will condense. The temperature at which the condensation happens is called the dew point.
Changes in States of Matter
Changes in States of Matter
What is needed to change from
one state of matter into another?
What will a liquid become if you add enough heat?
What will a liquid become if you remove enough heat?