States and Changes of Matter

States of Matter

• Three main states: solid, liquid, and gas.
• Solids have fixed shape and volume, high density, are incompressible, and cannot be poured.
• Liquids have a fixed volume but take the shape of their container, less dense than solids but denser than gases, are slightly compressible, and can be poured.
• Gases have no fixed shape or volume, low density, are highly compressible, and can be poured.

State Changes

• Melting: Solid to liquid; requires heat energy increasing kinetic energy; occurs at the melting point (m.p.).
• Boiling: Liquid to gas; requires heat forming gas bubbles; occurs at the boiling point (b.p.).
• Evaporation: Liquid to gas at the surface; occurs below the b.p. over a range of temperatures; faster with larger surface area and warmer temperature.
• Freezing: Liquid to solid; reverse of melting; occurs at the same temperature as the m.p.; requires a decrease in temperature.
• Condensation: Gas to liquid; occurs on cooling over a range of temperatures; particles lose energy and clump together.

Kinetic Theory of Matter

• Heating substances increases particle kinetic energy (thermal energy converted to kinetic energy).
• Heating a solid increases vibration until it melts, then further heating expands the liquid until boiling occurs.

Heating and Cooling Curves

• Graphical representations of temperature changes during heating or cooling. (Note: Specific details of curve shape not provided in text)

Hot Air Balloons

• Heated air expands, decreasing density and causing the balloon to rise.

Gas Temperature and Pressure

• At constant volume and amount of gas: higher temperature means higher pressure.
• This is because heated particles gain kinetic energy, hitting container walls more frequently and forcefully.