THE PARTICULATE NATURE OF MATTER

Learning Objectives 1.Properties of the three states of matter 2.The Kinetic Particle Theory 3.Explain the change in states using the Kinetic Theory and the energy involved

Properties of the Three States of Matter All matter has mass and occupies space SolidsLiquidsGases ShapeFixed shapeNo fixed shape. Takes the shape of its container No fixed shape. Takes the shape of its container. VolumeFixed volume No fixed volume. Takes the volume of its container Compressible?Incompressible Very compressible

The Kinetic Theory Why did the three states of matter appear this way? The Kinetic Theory suggests that all matter is made up of extremely small particles that are in constant motion. These particles can be atoms, molecules or ions.

SolidLiquidGas Diagram Arrangement of particles Packed closely in an orderly arrangement Packed closely in a disorderly arrangement Far apart in an disorderly arrangement Forces of attraction between particles Very strong forces of attraction Strong forces of attraction Weak forces of attraction Movement of particles Particles vibrate and rotate about fixed positions Particles can move and exchange positions within the liquid Particles are in random motion

Changes in States 1.Melting and Freezing 2.Boiling and Condensation 3.Evaporation 4.Sublimation

Changes in States Changes in state are due to the particles absorbing or losing energy. As a substance get heated, it absorbs energy and when it cools it loses energy. Gas Liquid Solid Energy of the particles Boiling Condensation MeltingFreezing

Melting Melting takes place when the particles in a solid absorb enough energy to overcome the forces holding them in fixed positions and rearrange themselves to form a liquid. Gains energy

Melting Temperature ( o C) Time from start (min) A BC D AB : Substance is in solid state. Particles absorbed heat energy and their vibration increases. BC : Melting occurs. Substance becomes a mixture of solid and liquid. Heat energy absorbed by particles is used to overcome forces of attraction between the particles. CD : Substance is in liquid state. Heat energy absorbed by particles and their kinetic energy increases. Temperature increases. Melting point of substance

Freezing takes place when the liquid particles loses energy to rearrange themselves to form back the solid structure. Freezing Loses energy

Temperature ( o C) Time from start (min) Freezing A BC D Freezing point of substance AB : Substance is in liquid state. Particles loses kinetic energy due to cooling. BC : Freezing occurs. Substance becomes a mixture of liquid and solid. Liquid particles rearrange themselves to form a solid structure upon further cooling. CD: Substance is in solid state. Particles loses energy upon cooling and their vibration decreases. Temperature drops. Freezing point and melting point the same temperature for the same substance?

Boiling Boiling takes place when the liquid particles gains enough energy to overcome the forces holding them together and move apart to form a gas. Gains energy

Boiling A BC D Temperature ( o C) Time from start (min) Boiling point of substance AB : Substance is in liquid state. Particles gain kinetic energy due to heating. BC : Boiling occurs. Substance becomes a mixture of liquid and gas. Liquid particles gain energy to overcome the forces holding them together and move apart to form a gas. CD: Substance is in gaseous state. Particles gain energy upon further heating and move further apart. Temperature increases.

Condensation Condensation takes place when the gas particles loses energy and move close together to reform the liquid structure. Loses energy

Condensation Temperature ( o C) Time from start (min) Condensation point of substance AB : Substance is in gaseous state. Particles loses kinetic energy due to cooling and move closer together. BC : Condensation occurs. Substance becomes a mixture of gas and liquid. Gas particles loses energy and move close together to reform the liquid structure. CD: Substance is in liquid state. Particles loses kinetic energy upon cooling. Temperature drops. A BC D Boiling point and condensation point the same temperature for the same substance?

Heating and Cooling Curves Melting Boiling liquid gas solid Temperature ( o C) Time from start (min) Temperature ( o C) Time from start (min) solid liquid gas Condensation Freezing Heating Curve Cooling Curve

Evaporation Evaporation is a physical process that changes a liquid into a gas. BoilingEvaporation Occurs at boiling pointOccurs at any temperature below boiling point Occurs throughout the liquid Occurs only at the surface of the liquid Bubbles observedNo bubbles observed Occurs rapidlyOccurs slowly

Sublimation Sublimation takes place when a solid changes into a gas directly, without going through the liquid state. Examples: Solid carbon dioxide (dry ice) iodine crystals moth balls

Summary Solid particles vibrate about a fixed position Liquid particles move about within the liquid Gas particles move energetically and apart from each other HEATING CURVE MeltingBoiling Solid particles vibrate fasterLiquid particles gain kinetic energy Gain enough energy to overcome forces of attraction between particles Rearrange to become liquidMove apart to become gas

COOLING CURVE CondensationFreezing Gas particles loses kinetic energy Liquid particles loses kinetic energy Move close togetherRearrange to form solid structure Reform liquid structure GRAPHICAL REPRESENTATION Single StateMultiple States (Change in State) solid, liquid or gassolid – liquid, liquid - gas Increase or decrease in temperature with time Temperature remain the same with time Curve or straight lineHorizontal line