Matter 1.3

Properties of Matter Include: How it looks (shiny, dull, colored) How it feels (hard, soft, rough, smooth) How it smells (sweet, salty, flowery) How it sounds (loud, soft, hollow) How it tastes (sweet salty, bitter, sour) What it does (bounce, bubble, tear)

Characteristic Properties Properties that do NOT change as mass, volume and/or shape change. Properties of a substance, not a specific object.

Characteristic Properties Because characteristic properties are usually not affected by physical changes, they can be used to identify matter.

Examples Include: boiling point melting point solubility conductivity hardness pH flammability density

Examples: color, size, shape, density, melting point, boiling point Physical Property Characteristic of a material that you can observe without changing the substance. Examples: color, size, shape, density, melting point, boiling point

Examples: flammable, combustible, may react to light Chemical Property Characteristic of a substance that indicates whether it can undergo a certain chemical change. Examples: flammable, combustible, may react to light

Physical Changes Physical Change Changes the form or appearance of a substance. (size, shape, state of matter) Does not change substance into anything new. Examples Whipping eggs Boiling water Dissolving sugar Dicing vegetables Melting ice Cutting paper Breaking glass © KeslerScience.com

Physical Changes Physical Changes Smooth Changing the state of matter Changing the color Changing the temperature Changing the shape Changing the texture Smooth Physical changes are limited to changes that result in a difference in display without changing the composition. Some common changes (but not limited to) are:  Texture Color Temperature Shape Change of State (Boiling Point and Melting Point are significant factors in determining this change.) Physical properties include many other aspects of a substance. The following are (but not limited to) physical properties.  Luster Malleability Ability to be drawn into a thin wire Density Viscosity Solubility Mass Volume  Any change in these physical properties is referred to as a physical change. © KeslerScience.com

Physical Changes Breaking Watermelon Ice Cream melting Patio cracking Breaking food into small pieces

Chemical Changes Chemical Change When two or more substances join to form new substances with new chemical properties. Examples Iron rusting Gas burning Eggs cooking Bread rising Fireworks explore, rusting metal Help student understand that when a chemical reaction occurs what they see is the chemical change. © KeslerScience.com

Chemical Changes Rusty car Sodium and chlorine make salt Digesting food

Evidence of Chemical Changes

Chemical Changes Combustion/Burning A chemical reaction between substances, usually including oxygen accompanied by giving off heat and or light. This is a permanent change that cannot be undone. Examples: Wood burning Candle Rusting © KeslerScience.com

Chemical Changes Bubbles Form When gases produced in a chemical reaction are released. Examples: Alka-Seltzer Bubbles in sodas © KeslerScience.com

Chemical Changes Unexpected Temperature Change During chemical bonding, energy is released or absorbed making their surroundings hotter or cooler. Examples: Adding salt to ice lowers its freezing point. Body temperature changes to fight infections. © KeslerScience.com

Chemical Changes Unexpected Color Change New molecules created in a chemical reaction radiate light differently producing new colors. Examples: Fireworks Leaves a change color © KeslerScience.com

Chemical Changes Precipitates Form When a solid suddenly appears in a solution and settles to the bottom, collects on another object, or makes the solution cloudy. Examples: Milk souring Bath tub rings © KeslerScience.com

Candle What is happening Is the candle changing? What does it mean to burn? What does it mean to melt?

Vinegar What is happening? Is anything being produced (created)? What are the bubbles?

Milk What is happening? Can we return to just milk?

Steel Wool What happened? Why do the steel wool samples smell different?

Reversing Chemical Changes Chemical changes produce new substances, therefore they usually cannot be undone Can’t change fried egg back to raw egg If they can be undone, they are undone by other chemical changes

The Law of Conservation of Mass Says that the mass of ALL substances present before a chemical change equals the mass of ALL substances after the change. When wood burns, it is changed into ashes oxygen and carbon dioxide and water vapor (the mass is still the same)!