Composition of matter (pure substances, elements, compound, mixtures and solutions)

Pure substances
• Are either elements or compounds
• They can not be broken down into simpler substances by ordinary means
• Examples: water, salt, aluminum, helium

• All atoms in an element are exactly alike
• 90 elements are found in nature
• Examples: copper, sulfer, gold

• substance in which two or more elements are combined in fixed porportions
• example water is H2O it is the elements Hydrogen and Oxygen combined
• Compounds have very different physical properties than the elements that make them up
• Example: salt(NaCl) is made up of two elements Chlorine and Sodium. Chlorine is a poisonous gas used in world war II and sodium is a metal that explodes when it comes into contact with water. But you probably eat salt every day.

Mixtures are made up of two or more substances that can be easily separated by physical means
• there are two types of mixtures ( heterogeneous and homogeneous)
• Heterogeneous mixtures
• A mixture in which the components are not blended evenly throughout
• example of a heterogeneous mixture is concrete( you can see the different parts) Pizza is also a heterogeneous mixture you can see the pepperoni and the cheese
• Homogeneous mixture is blended evenly throughout (no chunks)
• Example: Pepsi- you can not see the sugar or the Caffeine
• Another name for a homogenous mixture is a solution( a solution's particles never settle out)

Lab 1: Making Concrete
Ask your science facilitator for material to do the following in class:
1. Place 10g of crushed calcium carbonate, 20g of fine sand, and 30g of small, clean pebbles in a plastic cup.
2. Add 5g of water to the cup and stir thoroughly.
3. Allow the combined materials to dry overnight.
4. Remove the dry material from the cup. What is this material normally called. Which of the 4 groups of matter does it belong to?

Colloids is a type of mixture that never settles out
• a colloid's particles are larger than a solution's particles
• examples of colloids ( milk, fog, smoke)

Suspension- a heterogenous solution in which the particles settle out
• Example of a suspension: ( pond water, river water)
• River deltas are examples of how suspensions settle out
• The delta is formed as the particles in the river settle out as the river widens

Answer the questions in complete sentences.
1. How is a compound similar to a homogeneous mixture? How is it different?
2. Distinguish between a substance and a mixture. Give examples.
3. Describe the differences between colloids and suspensions.
4. Why is Vinegar considered a solution.

Physical Science Standards - 1A, 2B
English Content Standards - 1A, 2A, 2B, 3A, 4A, 5A, 10A, 11A, 11B, 12B, 13A