Unit One: Matter and Energy

1. Unit One:Matter and Energy

2. DON’T FORGET YOUR SAFETY QUIZ IS TOMORROW! Review Lab Safety: • What should you do if you finish a lab early? • Clean up the lab equipment and return back to your desks. • If you are using a Bunsen burner and need to leave your lab station what should you do? • Turn off the Bunsen burner. NEVER leave a Bunsen burner unattended. • If we are using the gas value and the fire alarm goes off what should you do? • Shut off the gas value before you leave the room. • Where is the fire blanket located? • Front, right side of the room. • Where is the fire extinguisher located? • Front, right side of the room. • Where is the eye wash located? • On the front desk, attached to the sink. • Name two safety precautions that should be taken before starting any lab. • Read all directions • Put safety goggles on • Tie back long hair • Make sure you know how to use the equipment! • Examine glassware before use

3. What is Chemistry?

4. What is Chemistry? • Webster’s Dictionary defines Chemistry as: • a science that deals with the composition, structure, and properties of substances and with the transformations that they undergo.

5. What is Matter? • Quick brainstorm with your lab partner! • Matter is defined as anything that has mass and volume • Volume is simply the amount of space an object occupies. • Liters (L) • Milliliters (mL) • Mass is the quantity of matter in an object. • Grams (g) • Kilograms (kg) • Milligrams (mg)

6. Are Mass and Weight the same thing? • No, mass is similar to weight but not the same thing! • Weight depends on gravity where as mass does not. • Since gravity varies from place to place weight varies as well. On Earth: 150 lbs Mercury: 56.7 lbs Venus: 136.05 lbs Neptune: 168.75 lbs The Moon: 24.9 lbs Mars: 56.55 lbs The Sun: 4060.8 lbs In chemistry we will use mass not weight!

7. Units of Matter • Atoms are the basic unit of matter. • Atoms do not usually exist by themselves, but instead combine to form clusters called molecules. • A molecule is a neutral group of atoms held together by chemical bonds.

8. Properties of Matter • In chemistry we describe different types of matter by listing their characteristics (or properties). • Color • Mass • Volume • Texture • Transparency • Flammability • Taste • Electrical Conductivity • Boiling Point • Freezing point • Malleability • Density

9. Physical Properties of Matter • Physical properties = properties that can be observed or measured without changing the composition of matter. • We use physical properties to identify things all the time!

10. States of Matter • The different states of matter are physical properties. • What are the different states of matter? • Solids have a fixed volume and shape. • Atoms and molecules are held tightly in a rigid structure but vibrate slightly about fixed positions. Solids

11. States of Matter • The different states of matter are physical properties. • What are the different states of matter? • Liquids have a fixed volume but variable shape. • The particles in a liquid are not held together in the rigid manner of solids. • Particles in liquids can “slip and slide” past one another. • As a result, the liquid as a whole is able to flow. Liquids

12. States of Matter • The different states of matter are physical properties. • What are the different states of matter? • Gases have no fixed shape of volume and therefore expand to fill any container they occupy. • This behavior in gases results from the fact that the particles are not held together, instead they are free to move about. Gases

13. States of Matter • The different states of matter are physical properties. • What are the different states of matter? • At very high temperatures, matter can exist as plasma. • In this high energy state, atoms are torn apart into smaller pieces. • The sun, stars, and other intergalactic matter are in the plasma state.

14. Chemical Properties of Matter • Chemical properties of matter tell us how substances interact. • In order to describe this type of behavior we refer to the chemical properties of the substance. • Chemical properties are those properties that are observed only when one substance interacts with another.

15. Is Air Matter? YES! NO! How can you show or “prove” that air is matter?

16. Is Air Matter? In the next 20 minutes I want you to explain to me how we know that air is matter! • Supplies you can use: • Test tubes • Graduate Cylinders • Scales • Large Balloons • Large Graduated cylinders • Film canisters • Water • 1000 mL Beakers • Small inflated balloons • On a sheet of paper: • Your procedure • What you measured/observed • An explanation of how you determined air has matter. Be prepared to share what you did!

17. Turn In: • Frist Part: • Your procedure • Your numbers (mass of the air in your balloon, with calculation along with the water change) • Second Part: • Your procedure • What happened • What it means • How do both of these show air is matter?

18. Try This: • With your lab partner come get: • Two large balloons • Two rubber bands • One push pin • You need a pencil or pen • Blow up the balloons and tie the rubber bands on the end • Place each balloon on each side of the pencil • Balance the pencil on your finger. • Now pop one balloon. • WHAT HAPPENED? WHY?

19. Observing Physical and Chemical Changes • A Physical changeis a change that affects physical properties only. • In a chemical change, one or more substances are changed into new ones. • In order to talk about physical and chemical changes we must first talk about energy. • Kinetic Energy- a type of energy that only moving objects have. • Potential Energy- is energy an object possesses because of its position.

20. Observing Physical and Chemical Changes • Energy is released or absorbed almost every time a physical or chemical change takes place • Kinetic Energy - The energy of motion • KE is indicated by measuring temperature • Potential Energy - The energy of position (stored energy) • Law of Conservation of Energy • Energy can be transferred from one object to another, or changed in form (KE to PE, PE to KE), but it is never created nor destroyed

21. Observing Physical and Chemical Changes • Exothermic – system gives off heat to surroundings when reaction occurs • Feels warm • PE being converted into KE • Endothermic– system absorbs heat from its surroundings when reaction occurs • Feels cold

22. Observing Physical and Chemical Changes • A Physical changeis a change that affects physical properties only. • When thinking about physical changes you need to picture what is happening on the molecular level. • Energy is also required. • For a gram of ice to change from a solid to a liquid (melt) 333 J of energy are required. • For a solid to melt its atoms or molecules must begin to move vigorously enough to break partially free of their neighbors and break down the solid crystal structure.

23. Observing Physical and Chemical Changes • A Chemical Change is when one or more substances are changed into new ones. • This change occurs at the atomic level, where atoms are rearranged without a loss or gain in the total number of atoms. • The substances that are undergoing the change are called the reactants and those created are called the products. • ALL CHEMICAL CHANGES ARE ACCOMPANIED BY TRANSFERS OF ENERGY.

24. Observing Physical and Chemical Changes • Chemical changes are either endothermic or exothermic, depending on whether they absorb or release energy. • In an endothermic reaction, the products have more energy than the reactants.

25. How to Identify Chemical vs. Physical Changes • Physical Changes: • Change in shape • Change in state • Change in size • Change in mass • Change in length • Chemical Changes: • Change in temperature • Gas formation • Solid forms from two liquids • Color change

26. Practice identifying physical and chemical changes