List 5 physical properties. Warm-Up List 5 physical properties. List 5 physical changes.

8th Grade Physical Science Chemical Properties 8th Grade Physical Science

What is the definition of physical property?

Physical Property A characteristic of a substance that can be observed without changing the substance into another substance

What are some physical properties?

Physical Property Examples: color, odor, shape, size, mass, volume, magnetism, ability to conduct electric current, strength, flexibility, texture, density, state, thermal conductivity, solubility, ductility, malleability, melting point, boiling point

What is a physical change?

Physical changes do not form new substances.

What are some physical changes?

Examples of Physical Changes Boiling Freezing Dissolving Breaking Making a mixture - 2 or more types of matter (substances) mixed together Can be separated physically All phase changes are physical changes!

Henry takes a cup of water and places it in the freezer Henry takes a cup of water and places it in the freezer. The liquid water changes to ice. Henry thinks this change is not a physical change, because the water changed into ice. Do you agree or disagree? Why?

What is a property? Property: a characteristic of a substance that can be observed 12

Two kinds of properties: Physical Properties and Chemical Properties

Physical Property A characteristic of a substance that can be observed without changing the substance into another substance

Chemical Property Describes matter based on its ability to change into new matter that has different properties

The ability of a substance to burn Flammability The ability of a substance to burn Wood has the chemical property of flammability. When wood is burned, ash and smoke are created.

Reactivity The ability of two or more substances to combine and form one or more new substances

Iron has the chemical property of reactivity with oxygen Iron has the chemical property of reactivity with oxygen. When iron reacts with oxygen, it rusts.

Video http://www.youtube.com/watch?v=uixxJtJPVXk

Substances can have chemical properties, even if you can’t observe them. A piece of wood is flammable even when it’s not burning.

Chemical Change Happens when one or more substances are changed into new substances that have new and different properties.

Chemical properties describe which chemical changes will occur and which will not occur.

Chemical change is the process by which substances actually change into new substances.

With paper, I know that it has the chemical property of flammability without even lighting it on fire.

It’s not until I light the paper on fire that the paper has a chemical change.

With baking soda, I know that it has the chemical property of reactivity with vinegar.

It’s not until I mix baking soda and vinegar that the two have a chemical change.

In a chemical change, the new product(s) are different from the substances that were initially combined together.

+ Carbon dioxide + Water

Burning wood is a chemical change. The wood is changed to ash and smoke.

Signs of a Chemical Change Change in Color Production or Change in Odor Change in Temperature Production of Precipitate (solid) Production of a Gas (bubbling)

Many physical changes are easily reversed. Most chemical changes are not easily reversed.

When determining if the change is physical or chemical, you should ask yourself if the composition changes.

The composition of an object is the type of matter that makes up the object and the way that the matter is arranged in the object.

Physical changes DO NOT change the composition of a substance.

Chemical changes alter the composition of the substance.

Physical Change or Chemical Change?

Physical The composition stays the same. Substance is not changed, just size or shape Change can be undone. Color changes (careful!) Changing State Dissolving Bending, Crushing, Mixing, Cutting, etc. Chemical The composition changes. Change CANNOT be undone. Color changes (careful!) Production of gas (bubbles) Production/Change in odor Change in temperature Production of precipitate

Cracking Eggs

Physical Change Cracking an egg separates the shell from the insides. The substances do not change.

Slicing Bread

When the bread is sliced, the bread just changes size and shape. Physical Change When the bread is sliced, the bread just changes size and shape.

Lighting a Match

The phosphorus and wood are changed into new substances. Chemical Change The phosphorus and wood are changed into new substances.

Rusty Nails

Chemical Change Oxygen in the air reacts with the metal of the nail. This produces a new substance called rust.

Ice Melting

Physical Change The ice just changes from solid to liquid. The water does not change into a new substance.

Glass Breaking

Physical Change The glass does not change into a new substance.

Boiling Water

Physical Change When water boils, water changes from a liquid to a gas. The identity of the water does not change.

Mixing Lemonade Powder into Water

Evaporating the water separates the ingredients. Physical Change After mixing the lemonade powder and water, lemonade powder and water are still present. Evaporating the water separates the ingredients.

Baking a Cake

Chemical Change The flour, eggs, sugar, baking powder, and other ingredients change into a new substance.

Mowing the Lawn

Cutting the grass does not change the identity of the grass. Physical Change Cutting the grass does not change the identity of the grass.

Fireworks Exploding

Chemical Change Fireworks are composed of different metals, such as copper. After ignited, the fireworks produce light, heat, and sound.

Melting Butter for Popcorn

Physical Change Heating causes the butter to change from a solid to a liquid. The identity of the butter does not change.

Hammering Wood Together to Build a Birdhouse

Physical Change Hammering the wood together causes the wood to change shape. The identity of the wood does not change.

Spoiling Food

Chemical Change Spoiling food changes color and has a foul odor. Bacteria, mold, enzyme action, and oxidation cause spoilage.

Separating a Mixture of Rocks and Sand

Physical Change Separating the rocks from the sand can be done by physical means. The identities of the rocks and sand do not change.

Exit Slip Define and give an example of a physical property. Define and give an example of a physical change. Define and give an example of a chemical property. Define and give an example of a chemical change.