Overview
This lecture covers the key steps of the water cycle and explains the three states of matter, including particle behavior and phase changes.
The Water Cycle
- The water cycle is the continuous movement of water on Earth.
- Condensation is when clouds become full of water vapor.
- Rainfall describes water returning from clouds to Earth.
- Runoff is rainwater flowing downhill into water bodies.
- Infiltration occurs when runoff flows into larger bodies of water by soaking into the ground.
- Precipitation is when water drops become too heavy and fall as rain.
- Surface runoff is water flowing over land into streams and rivers.
- Groundwater is water that soaks into soil and moves underground to larger water bodies.
- Solar radiation is the heat energy provided by the sun.
- Transpiration is water vapor released from plant leaves and stems.
States of Matter
- Matter is anything that has mass and takes up space.
- The three states of matter are solid, liquid, and gas.
- Solid particles are tightly packed with strong forces and low energy.
- Liquid particles have no set shape but definite volume with moderate forces and energy.
- Gas particles move freely with almost no attraction and highest energy.
- Kinetic refers to movement.
Changes of State
- Gas to solid is called deposition.
- Gas to liquid is called condensation.
- Solid to liquid is called melting.
- Liquid to solid is called freezing.
- Solid to gas is called sublimation.
- Liquid to gas is called evaporation.
- Water freezes at 0°C (32°F).
- Water boils at 100°C (212°F).
Properties and Particle Behavior
- Expansion is when something gets bigger, usually due to heating.
- Contraction is shrinking in size or volume, usually when cooled.
- Diffusion is particles moving from crowded to less crowded spaces.
- Gas particles diffuse fastest due to their high energy and wide spacing.
Key Terms & Definitions
- Condensation — Change from gas to liquid; clouds forming from water vapor.
- Precipitation — Water falling from clouds as rain.
- Transpiration — Water vapor released from plants.
- Runoff — Water flowing over land into bodies of water.
- Infiltration — Water soaking into the ground to become groundwater.
- Deposition — Gas changes directly to solid.
- Sublimation — Solid changes directly to gas.
- Diffusion — Movement of particles from high to low concentration.
Action Items / Next Steps
- Review the definitions and processes in the water cycle.
- Memorize phase change names and temperatures for water.
- Practice distinguishing particle behavior in solids, liquids, and gases.