Sixth Grade Science

Physical ChangeA physical change is a type of change that

does not change what the substance is.If you put a cup of water in the freezer, the

liquid water turns to ice. Is the ice still water? Yes! Ice is water in solid state. You can melt ice and get liquid water back.

When you tear a paper into pieces, each piece is still made up of the same material as the whole piece of paper. The pieces are still paper.

Physical Change ExamplesIce melting (just changes form)Blowing a dandelion (just changes location)Chocolate bar melts (just changes shape)Glass broken (just changes shape/size)Rock weathers into pebbles (just changes

shape/size)Making chocolate milk (just changes color,

can be separated)

Chemical ChangeDuring a chemical change, substances

are changed into different substances.A chemical change not only alters the

substance’s physical properties, but actually changes it into something new.

Signs of a Chemical ChangeColor changes

When leaves change color in the fall

When an apple turns brown after it’s been left out

Signs of a Chemical ChangeEnergy is released or

absorbed: light or temperatureFireworks release energy as

light

During cooking, like baking a cake, energy as heat is absorbed

Signs of a Chemical ChangeChange in odor

Spoiled food smells bad!

Signs of a Chemical ChangeProduction of gases or

solidsThe bubbles of gas that you

observed form when an antacid is dropped into water

A solid that separates out is called a precipitate

Signs of a Chemical ChangeNot easily reversed

After wood burns, ash cannot be made into wood again

ImportantIn a physical change, the composition of a

substance DOES NOT CHANGE. However, in a chemical change, the

composition of a substance DOES CHANGE.

Chemical Change ExamplesBaking a cake (change in color, change in

temperature)Striking a match (energy released as light and

heat)Bleaching hair (change in color, change in odor)Garbage rotting (change in temperature, change

in odor)Bicycle rusting (change in color)Plants making oxygen (energy (sunlight) is

absorbed, new gas forms)

Law of the Conservation of MassThe mass of what you end with is always equal to the mass of what you start with.Example: Baking a cake—If you measured the mass of the batter, and then measured the mass of the cake after it was baked, they would be the same!Mass is not destroyed or created during chemical reaction, just changed.

Brain Pop VideoProperty Changes

Physical or Chemical Change?Milk is warmed up.Water is heated and changed to steam. Iron rusts. Ice melting. Milk sours. Sugar dissolves in water. Wood rotting.

Physical or Chemical Change?Pancakes cooking on a griddle. A tire is inflated with air. Food is digested in the stomach. Water is absorbed by a paper towel. A glass is broken. A pot of water is boiling. Dough is baked into a cake.

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