Chemical Properties Chemical Properties and Changesand Changes

Science 6th Grade

• It is important to never taste, touch, or smell any of the materials being used in the lab without guidance.

• For safety reasons you will rely mostly on other observations.

Using Your Senses

Safety in the ClassroomSafety in the Classroom

Ability to Change• Some properties indicate a change of identity

for the substances involved.

• A chemical property is any characteristic that gives a substance the ability to undergo a change that results in a new substance.

Chemical Properties and ChangesChemical Properties and Changes

Common Chemical Properties

• A chemical change is a change in the identity of a substance due to the chemical properties of that substance.

• A new substance or substances are formed as a result of such a change.

Chemical Properties and ChangesChemical Properties and Changes

• Wood can burn.

• This chemical property is called flammability.

• Some products have warnings on their labels about keeping them away from heat and flame because of the flammability of the materials.

Chemical Properties and ChangesChemical Properties and Changes

Common Reactions

• An unpainted iron gate or mailbox will rust in time.

• The rust is a result of oxygen in the air reacting with the iron and causing corrosion.

• The corrosion produces a new substance called iron oxide, also known as rust.

Chemical Properties and ChangesChemical Properties and Changes

Common Reactions

• Tarnish develops on silver when it reacts with sulfur in the air.

• The ability to react with oxygen or sulfur is a chemical property.

Chemical Properties and ChangesChemical Properties and Changes

Heat and Light• Many vitamins will change when exposed

to light.

• This is a chemical property.

• They are protected in colored bottles from undergoing a chemical change with light.

Chemical Properties and ChangesChemical Properties and Changes

Heat and Light• Some substances are sensitive to heat and

will undergo a chemical change only when heated or cooled.

• One example is limestone.

• If limestone is heated, it goes through a chemical change and produces carbon dioxide and lime.

Chemical Properties and ChangesChemical Properties and Changes

Heat and Light• Another chemical property is the ability

to change with electrical contact.

• Electricity can cause a change in some substances and decompose some compounds.

• Water is one compound that can be broken down with electricity.

Chemical Properties and ChangesChemical Properties and Changes

Signs of Change

• You can look for signs when evaluating whether you have a new substance as a result of a chemical change.

Chemical Properties and ChangesChemical Properties and Changes

Signs of Change

• Bubbles are a sign that a chemical change has taken place.

• Other signs of change include the production of heat, light, smoke, change in color, and sound.

Chemical Properties and ChangesChemical Properties and Changes

Examples of Chemical Properties

Chemical Properties and ChangesChemical Properties and Changes

Is it reversible?

• Chemical changes can’t be reversed using physical means.

• For example, the ashes in a fireplace cannot be put back together to make the logs that you had to start with.

Chemical Properties and ChangesChemical Properties and Changes

• The physical properties of a substance are easily observed, but the chemical properties can’t be observed without changing the substance.

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• However, once you know the chemical properties, you can classify and identify matter basedon those properties.

Chemical Properties and ChangesChemical Properties and Changes

The Law of Conservation of Mass

• The law of conservation of mass states that the mass of what you end with is always the same as the mass of what you start with.

• One experiment done by French scientist Antoine Lavoisier was a small version of a campfire.

• He determined that a fire does not make mass disappear or truly get rid of anything.

Where did the mass go?• When flammable

materials burn, they combine with oxygen. Ash, smoke, and gases are produced.

• The smoke and gases escape into the air.

Where did the mass go?

• If you could measure the mass of the oxygen and all of the original firewood that was burned and compare it to the remaining mass of the ash, smoke, and gas, they would be equal.

• Mass is not destroyed or created during any chemical change.

Which is a chemical property?

1. Flammability

2. Color

3. Density

4. Shape

As you cook marshmallows over a fire, you watch the logs slowly turn to ash. What process are you observing?

1. Chemical change

2. Chemical property

3. Physical change

4. Physical property

When a chemical change takes place, what is formed?

1.1. a new substancea new substance

2.2. an unpredictable substancean unpredictable substance

3.3. more of the same substancemore of the same substance

4.4. nothingnothing

When a newspaper is left in direct sunlight for a few days, the paper begins to turn yellow. What is the yellow color evidence of?

1. A physical property

2. A physical change

3. A chemical property

4. A chemical change

1. Same density

2. Ability to burn

3. ability to dissolve in water

4. Same boiling point

Which of the following chemical properties is shared by alcohol, olive oil and gasoline?

What is the ability of an apple to change color when exposed to air called?

1. A physical property

2. A physical change

3. A chemical property

4. A chemical change

1. A change in state

2. The release of a gas

3. A change in color

4. The release of energy

Which of the following is not a possible sign of a chemical change?

Photosynthesis in plants is an example of which of the following?

1. A chemical change

2. A chemical property

3. A physical change

4. A physical property

When a chemical change takes place, what is formed?

1. a new substance

2. an unpredictable substance

3. more of the same substance

4. nothing

An example of a chemical property is the ability to react with oxygen.

1. True

2. False

The law of conservation of matter states that the mass of the products of a chemical reaction would be less than the mass of the reactants.

1. Yes

2. No

The ability to reverse a change in matter indicates that it was a chemical change.

1. True

2. False

Which is a chemical property?

1. flammability

2. color

3. density

4. shape

Using the table, a material that is colorless and has a density of 1.45 grams per millimeter is ____.

1. Rock

2. Hydrogen Peroxide

3.Water

4. Aluminum

Which property in the table is an example of a chemical property?

1. State of Matter

2. Color

3. Density4. Reacts with light

How can you tell that exploding fireworks during a typical New Year display do not contain the same ingredients?

1. The casings look different

2. The materials produced have different colors

3. It cannot be determined

4. The starting materials are all the same

When a shiny penny turns dull, which of the following has happened?

1.1. A physical changeA physical change

2.2. A chemical changeA chemical change

3.3. A phase changeA phase change

4.4. The penny has been exposed to The penny has been exposed to acidacid

Credits:Images from Microsoft Office Clipart

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Adopted Textbook: Glencoe Florida Science 6th Grade

PowerPoint Adapted/edited from Teacher Resource File