1. Chapter 2 Matter All the materials you can hold or touch are matter.

2. What Is Matter? You are made of matter Your textbook is made of matter. The air you breathe is matter. Anything that has mass and occupies space is matter. Light, Sound, and Electricity are NOT matter because they have no mass or volume!

3. Matter All matter is made up of atoms. Element – a substance that cannot be broken down into simpler substances. Atom – the smallest particle that has the properties of an element Compound – a substance made of atoms of more than one element bound together.

4. Earth

5. Human Body

6. Matter Molecule – the smallest unit of a substance that exhibits all of the properties characteristic of that substance –H 2 O –CO 2 Chemical formula – the chemical symbols and numbers indicating the atoms contained in the basic unit of a substance –C 16 H 10 N 2 O 2

7. Matter Pure substance – any matter that has a fixed composition and definite properties. –CO 2 - C 3 H 8 O –H 2 O Mixture – a combination of more than one pure substance. –Milk –Grape juice –Windex

8. Mixtures Homogeneous – mixing occurs between the individual units and is the same throughout –Salt dissolved in water Heterogeneous – not uniformly mixed –Flour suspended in water

9. Mixtures Miscible – describes two or more liquids that are able to dissolve into each other in various proportions –Rubbing (denatured) alcohol Immiscible – describes two or more liquids that do not mix into each other. –Oil and vinegar salad dressing

10. Matter and Energy

11. Kinetic Theory All matter is made of atoms and molecules that act like tiny particles. These tiny particles are always in motion. The higher the temperature, the faster the particles move. At the same temperature, more massive (heavier) particles move slower than less massive (lighter) particles.

12. Kinetic Theory The kinetic theory is a useful tool for visualizing the differences between the three common states of matter: solids, liquids, and gases –Solids – have a rigid structure –Liquids – have a less rigid structure than solids and can move about, or flow. Liquids have a definite volume that can be measured.

13. Kinetic Theory The kinetic theory is a useful tool for visualizing the differences between the three common states of matter: solids, liquids, and gases –Gases – gases are in a constant state of motion and rarely stick together Gases will fill any container Due to their rapid movement, a gas exerts pressure on its container

14. Change of state for water 0 C 100 CSolid ice Liquid water Gaseous steam Relative energy 540 cal./g 80 cal/g 1 cal/g/ o C

15. Change of state for water 0 C 100 CSolid ice Liquid water Gaseous steam Relative energy 540 Calories per gm / C 80 Calories per gm / C Melting (energy absorbed) Freezing (energy released) Evaporation (energy absorbed) Condensation (energy released

16. Energy’s Role Energy must be added to cause melting or evaporation Energy is transferred in all changes of matter Changing state does not change composition or mass Evaporation – the change of a substance from a liquid to a gas

17. Energy’s Role Sublimation – the change of a substance from a solid to a gas –Dry ice (solid CO 2 ) –Ice and snow at very high altitudes will sublime –Ice in your freezer at home will sublime Whether it is ice, water, or steam, water in any form is always made of H 2 O molecules.

18. Energy’s Role Law of Conservation of Mass – Matter can neither be created nor destroyed. Law of Conservation of Energy – Energy can neither be created nor destroyed. [See figure 2-17 on page 51 of text.] Mass A (wood + air) = Mass B (carbon + carbon dioxide + water)

19. Properties of Matter

20. Chemical and Physical Properties Chemical property – the way a substance reacts with others to form new substances with different properties. –Involve the reactivity of elements or compounds –Flammable –Able to rust or oxidize Reactivity – the ability of a substance to combine chemically with another substance.

21. Chemical and Physical Properties Physical property – a characteristic of a substance that can be observed or measured without changing the composition of the substance. Physical Properties –Shape, color, odor, texture –Melting point, boiling point, density, strength, hardness, conductivity, etc.

22. Chemical and Physical Properties Physical Properties Melting point – the temperature at which a solid becomes a liquid Boiling point - the temperature at which a liquid becomes a gas (below the surface)

23. Chemical and Physical Properties Physical Properties Density – is calculated by dividing the object’s mass by its volume. D = m V, or D = m/V Buoyancy – the force with which a more dense fluid pushes a less dense substance upward. [An object will displace a volume of water up to its own weight; otherwise it will sink.]

24. Density of some items Item Chem Formula Density g/cm 3 AirMixture0.00129 GasolineMixture0.7 Water H2OH2OH2OH2O1.00 LeadPb11.3 IronFe7.86 HeliumHe0.00018 Ice H2OH2OH2OH2O0.92

25. Chemical and Physical Properties Properties help determine uses –Copper is used in electrical power lines, telephone lines, and electrical motors because of its good electrical conductivity. –Ethylene glycol remains a liquid at temperatures that would normally boil or freeze in a car radiator. (Antifreeze)

26. Chemical and Physical Changes Chemical: Materials that change and combine –Gasoline, Car batteries –Human metabolism (oxidation) –Digestion, etc. Physical: Materials that stay in the same state under normal conditions –Surgical steel, Concrete, Glass

27. Chemical Properties Chemical change result in a change in composition. Chemical changes occur when atoms gain, lose, or share electrons. The atoms are “rearranged”!

28. Chemical Properties Electrolysis – the process by which water can be broken down into hydrogen and oxygen. –The atoms of oxygen and hydrogen are not destroyed, but rearrange themselves to form hydrogen and oxygen gas. [See figure 2-22 in text.] –Burning of gasoline into C, CO 2, & H 2 O –A change in odor or color is a good clue that a substance is changing chemically i.e. food burning, paint fading, etc.

29. Physical Properties Physical change does not change composition i.e. solid, liquid, gas, dissolving, etc. Physical change – a change in the physical form or properties of a substance without a change in composition. –Grinding Quartz crystals into sand –Grinding peanuts into peanut butter –Making gold jewelry