UNIT 1 Matter Day 7 September 8, 2017 Physical and Chemical Properties of Matter 8th Grade Science

Do this NOW!!! Answer the E.Q. on page 7. Your answer can be an example. How do physical properties make different substances useful for different purposes? LOOK BACK AT YOUR NOTES AND CHOOSE A PROPERTY.

Sept. 8, 2017 Plan for today: 1. E. Q. 2. Concept web on physical and chemical properties 3. Scavenger Hunt 4. Physical Change

Essential Question - How are physical properties different from chemical properties? .

Homework: Make flash cards for any new terms on the vocab. sheet – due Monday Worksheet – Physical vs. Chemical Properties Quiz next Weds. on physical and chemical properties and change – study flash cards

Let’s work on the concept web starting with physical properties.

Physical property Can be observed without changing the substance Ex. Shape - Smashing an orange (it’s still an orange, just a flat one); State of Matter -melting an ice cube (it’s still water, just in liquid form)- same substance before and after

Observable properties – we use our senses to gain info about the object/substance

measurable properties – we use tools to gain info about the object/substance

Measurable Properties of Matter Temperature – A measure of how hot or cold a substance is. Calculate – Use a thermometer Unit – degrees Fahrenheit/ Celsius (in USA we use F)

Boiling point: the temperature at which a substance changes from a liquid to a gas at a given pressure water (H2O) = 100o C (212o F) Calculate – Use a thermometer

Melting point: the temperature at which a substance changes from a solid to a liquid at a given pressure water (H2O) = 0o C (32 o F) Calculate – Use a thermometer

Freezing Point: the temperature at which a substance changes from a liquid to a Solid at a given pressure water (H2O) = 0o C (32 o F) Calculate – Use a thermometer

Let’s fill in the physical properties.

Now to chemical properties!

chemical property Can only be observed when substances are changing into new substances. Ex. Reactivity – Baking soda and vinegar are reactive with one another, but you can’t SEE that reactivity until you mix them-mix them and they produce CO2 gas (a new substance)-different substances before and after

Reactive Chemical Properties of Matter :Examples Ability to rust – IRON undergoes an oxidation reaction with moisture and air Tarnish – To become dull or discolored Radioactivity – decay of elements into high energy particles – NUCLEAR energy Corrosion – Deterioration of metal by means of a chemical reaction

Answer the e.q. on page 9. How are physical properties different from chemical properties?

Scavenger hunt

13. Physical Change Def. - a change that affects one or more physical properties of a substance. A.D. Only changes the appearance of the substance/object; does NOT change the composition or identity of the substance;  Ex. melting a stick of butter or a popsicle; freezing water to make ice cubes; crushing a can most are easily reversible.

Summing up Physical Change… A PHYSICAL change does not result in a new substance being formed. It only changes the appearance of a substance. Ex. Melting ice – Solid water Liquid water It’s still water!!!!! Ex. Shaping a gold bar into jewelry It’s still gold!!!!

Oobleck Lab

The Oobleck has been prepared for you ahead of time *The Oobleck has been prepared for you ahead of time. (If you want to make it at home, it's 2 parts cornstarch to 1 part water:) Procedure: 1. You will work together as a group (and you know I mean it). 2. The recorder will record your group's observations on one lab sheet. Technical manager should let me know if any group members are not participating or are cutting up, or if the recorder is not doing his/her job. 3. As a group, discuss and complete the Pre-Investigation Review on the "Monster Muck" sheet. 4. There are 8 tests to complete with the Oobleck. They are on a sheet at each station. Allow everyone to test the Oobleck. But keep in mind that you have an observation sheet to complete. 4. When you finish the 8 tests, discuss and answer. 5. Clean up your table.

https://www.youtube.com/watch?v=D-wxnID2q4A

A few more things about heat and density…

Why are some objects less dense than other objects? The further apart the molecules of a substance are, the lower its density.

What causes molecules to spread? Adding energy (usually in the form of heat) so the movement of the molecules increases.

Objects float in other substances because they are less dense than the substance they are floating in. Why does ice float in water? They are both the same substance, right?

The spaces between the atoms make solid water less dense. Notice how tightly packed the atoms are in the liquid water vs the solid water? The spaces between the atoms make solid water less dense. Is this true for all solids? NO WAY!!! This is a unique quality of water. Most solids are always more dense than their liquid forms.

DENSITY When does an object’s density change? If heat is added or taken away!!!! HEAT – spreads out molecules and makes them LESS dense Take AWAY heat – molecules come together and makes them MORE dense. Water vapor (gas…particles have a lot of energy and are moving fast) is less dense than liquid water! Hot water is less dense than cold water.

To recap… Density is a result of how tightly atoms/particles are packed in a given space. Heat affects density. As heat (thermal energy) is added, particles become more energized and move further apart. Density then decreases.

WRAP-UP - Group work review of physical properties vs WRAP-UP - Group work review of physical properties vs. chemical properties Work with your group to complete the worksheet. Tape this worksheet to page 10 . If time allows, work on your flash cards.