KMS 8 th grade Science Chapter 6: States of Matter

Introduction to Chemistry Chemistry – Matter - The study of the properties of matter and how matter changes Anything that has mass and takes up space (that space is volume)

Lesson 1 – Solids, Liquids and Gases What types of matter do you see in this picture? Air (gas) Bubbles (liquid) Water (liquid) metal sign (solid)

Most Common Phases of Matter Solid Liquid Gas How can matter be described? State Color Texture Odor Measurements (volume, mass, density)

Solids Matter that has definite shape and definite volume. Arrangement of Particles: How do these particles move? Illustration of particle arrangement. Very close together Vibrate in place

Liquid Matter that has no definite shape but has a definite volume. Arrangement of Particles: How do these particles move? Illustration of particle arrangement. Further apart than particles in a solid (greater potential energy) More freely. Particles take shape of container.

Gas Matter that has no definite shape or no definite volume. Arrangement of Particles: How do these particles move? Illustration of particle arrangement. Large distance between particles. Greatest amount of potential energy. Quickly and freely.

Particle illustrations

When talking about liquids you should know… Viscosity The stronger the attraction between forces Examples: High Viscosity vs. Low Viscosity Surface tension A measurement of a liquids resistance to flow. the higher the viscosity Uneven forces acting on the particles on the surface of a liquid

When talking about gas you should know… Vapor Evaporation The gas state of a substance that is normally a solid or a liquid at room temperature. Vaporization that occurs only at the surface of a liquid.

Lesson 2: Changes in State What change of state are you observing? As a snowman melts you observe a solid turning into a liquid.

Changing an objects state You can change an objects state of matter by adding or removing When you add thermal energy: When you remove thermal energy the opposite occurs: Particles slow down (kinetic energy decreases) or move closer together (decrease potential energy) or both. thermal energy The particles move faster (increased kinetic energy) or move farther apart (increased potential energy) or both.

Solid to Liquid or Liquid to Solid Melting Freezing To change matter from a solid to a liquid. Thermal energy must be added. To change matter from a liquid to a solid. Thermal energy must be removed.

During the solid phase Temperature stops increasing when it reaches which is the temperature at which The horizontal line indicates that Once the phase change is complete The reverse occurs when going from a liquid state to a solid state. temperature and thermal energy increase. melting point solid changes to liquid. temperature has stopped increasing but thermal energy continues to increase. thermal energy (PE) slows down and temperature (KE) begins to rise again.

Liquid to Gas or Gas to Liquid Boiling Condensation Vaporization that occurs throughout a liquid. Changes liquid to a gas. The change of state from a gas to a liquid. When vapor cools back to a liquid.

What is the main difference between evaporation and boiling? During evaporation a substance vaporizes only at the surface. During boiling a substance vaporizes at the surface but also within the liquid.

During the liquid phase Temperature stops increasing when it reaches which is the temperature at which The horizontal line indicates that Once the phase change is complete temperature and thermal energy increase boiling point liquid changes to gas temperature (KE) has stopped increasing but thermal energy (PE) continues to increase. thermal energy (PE) slows down and temperature (KE) begins to rise again. The reverse occurs when going from a gas to a liquid

Is it possible for a solid to become a gas without becoming a liquid first? YES! This is called Sublimation Deposition Sublimation The change of state from a solid to a gas without going through the liquid state The change of state of a gas to a solid without going through the liquid state.

Phase Changes

Energy can never be created or destroyed… for matter to change phases thermal energy is transferred.

Lesson 3: Behavior of Gases

Pressure and Volume Pressure Volume The amount of force applied per unit of area. The amount of space an object occupies.

Pressure and Volume As volume pressure with the same number of particles. Does the number of particles change from the first illustration to the last? What is happening in the picture? decreasesincreases No, the number of particles remain the same. As the plunger moves down, pressure increases and volume decreases.

Boyle’s Law Pressure of a gas increases if the volume decreases and pressure of a gas decreases if the volume increases when the temperature is constant. Robert Boyle Have your ears ever popped in an airplane or in the car? Use Boyle’s Law to explain how this happens. On the ground (at sea level) air pressure inside your ear and the pressure of the air surrounding your ear are equal. When you increase altitude air pressure surrounding your ear decreases while the pressure in your ear stays the same causing increase in volume. This causes the pain you feel. British scientist who was the first to describe the properties of gases.

Charles’s Law The volume of a gas increases with increasing temperature, if the pressure is constant. Jacque Charles What happens to a full balloon if you take it outside on a cold winter day? French scientist who described the relationship between temperature and volume of gas. When the balloon is in the cold air, the temperature of the gas inside the balloon decreases, causing the particles to slow down and come close together. Fewer particles hit the inside of the balloon causing it to look deflated.