1. Beaker Breaker!! 1.)When two atoms are touching based on the activity yesterday that means it is considered a___________ 2.)What do the small numbers (subscripts) represent in H 2 O?

2. Chapter 2 Properties of Matter 2-1 Classifying Matter

3. Objectives 1.Classify pure substances as elements or compounds 2.Describe the characteristics of an element and the symbols used to identify elements 3.Describe the characteristics of a compound

4. Pure Substances Matter that always has exactly the same composition is classified as a pure substance. Every sample of a given substance has the same properties because a substance has a fixed, uniform composition. Ex – Table Salt (Na) and sugar(C 6 H 12 O 6 ) Can be classified into elements and compounds

5. Elements Element is a substance that cannot be broken down into simpler substances. Atoms are the smallest particle of an element. An element has a fixed composition because it contains only one type of atom.

6. Examples of Elements Most are solids – Aluminum (Al) Some are gases – Carbon (C) Two are liquids are room temperature – Bromine (Br) and Mercury (Hg)

7. Symbols for Elements The first letter is always capitalized If there is a second letter it is not capitalized -Na (sodium) If the symbol contains only one letter, it is always capitalized - C

8. Compounds A compound is a substance that is made from two or more simpler substances and can be broken down into those simpler substances. A compound always contains two or more elements joined in a fixed proportion. Ex. Water – H 2 O

9. Mixtures The properties of a mixture can vary because of composition of a mixture is not fixed. Example - Salsa

10. Beaker Breaker!! 1.) Can an element or a compound be broken down into simpler parts? 2.) What is an example of a pure substance? 3.)What are the building blocks of elements?

11. What is a mixture? Variable combination of 2 or more pure substances. HeterogeneousHomogeneous

12. What is the difference between a homogeneous and a heterogeneous substance? Heterogeneous: substance whose composition is not uniform throughout……always a mixture

13. What is the difference between a homogeneous and a heterogeneous substance? Homogeneous: substance that is uniform (same) in its composition

14. A mixture may be… Homogeneous (same) Heterogeneous (different)

15. Solutions When substances dissolve and form a homogeneous mixture, the mixture that forms is called a solution. Ex: tap water and windshield wiper fluid Light passes through liquid solutions without being scattered in all directions

16. Suspensions A heterogeneous mixture that separates into layers over time is called a suspension. Ex: Shaking a jar of sand and water

17. Colloids A colloid contains some particles that are intermediate in size between the small particles in solution and the larger particles in a suspension. Fog is a colloid of water droplets in air Scattering of light is a property of a colloid

18. Beaker Breaker!! 1.) When substances dissolve and form a homogeneous mixture, the mixture that forms is called a___________. 2.) Is fog an example of a colloid or a suspension? 3.) A heterogeneous mixture that separates into layers over time is called a_____________

19. Solutions Cont. Recall that a solution is a homogeneous mixture of two or more substances Two components 1.Solute 2.Solvent

20. Solutes A solute is a substance whose particles are dissolved in a solution.

21. Solvents The substance in which the solute dissolves is called the solvent.

22. Example Seawater solution Solute = salt Solvent = water

23. Beaker Breaker!! 1.) A__________________is a substance whose particles are dissolved in a solution. 2.) The substance in which the solute dissolves is called the ___________________. 3.) sugar in water – circle the solvent and underline the solute

24. 2-2 Physical Properties A physical property is any characteristic of a material that can be observed or measured without changing the composition of the substances in the material

25. Examples of physical properties 1. Viscosity 2. Conductivity 3. Malleability 4. Hardness 5. Melting Point 6. Boiling Point 7. Density

26. Viscosity The tendency of a liquid to keep from flowing – resistance to flowing is called viscosity. Example - Honey

27. Conductivity A material’s ability to allow heat to flow is called conductivity Example : Metals = high conductivity or also know as conductors Stirring soup with a metal soup verses wooden spoon

28. Malleability Malleability is the ability of a solid to be hammered without shattering. Ex gold and aluminum

29. Hardness One way to compare the hardness of two materials is to see which of the materials can scratch the other. Ex: Kitchen knife (stainless steel) scratching copper

30. Melting Point and Boiling Point The temperature at which a substance changes from a solid to a liquid is its melting point. The temperature at which a substance boils is its boiling point Ex: Water at 0 degrees Celsius and 100 degrees Celsius

31. Density Density can be used to test the purity of a substance. Density = Mass Volume Ex: Silver coin density = 9.9g/cm 3 Actual density of silver = 10.5g/cm 3 Coin is not pure silver

32. Beaker Breaker!! 1.) Name one of the seven physical properties________________ 2.) Which physical property is defined as a material’s ability to allow heat to flow? 3.) Aluminum and Gold are examples are what physical property?_____________

33. Using Properties to Separate Mixtures 1.Filtration is a process that separates materials based on the size of their particles 2.Distillation is a process that separates the substances in a solution based on their boiling points.

34. Recognizing Physical Changes A physical change occurs when some of the properties of a material change, but the substances in the material remains the same. Ex: slowly heating butter in a pan –changes from solid to liquid, but the substance in the butter remains the same. Slicing a tomato Crumpling a piece of paper

35. Chemical Properties A chemical property is any ability to produce a change in the composition of matter. Chemical properties can be observed only when the substances in a sample of matter are changing into different substances.

36. Examples 1.Flammability is a material’s ability to burn in the presence of oxygen. Ex. Gasoline and paper

37. Reactivity The property that describes how readily a substance combines chemically with other substances is reactivity. Example – gases in air Oxygen is highly reactive Nitrogen has a low reactivity - Rust is another example

38. Recognizing Chemical Changes A chemical change occurs when a substance reacts and forms one or more new substances. Examples: cake baking in oven leaves on trees change color food digested in your stomach

39. Three common types of evidence 1.Change in color 2.The production of a gas 3.The formation of a precipitate

40. A change in color Ex: silver tarnishing a match burning then turning black and shrivels

41. Production of a Gas Ex: Combining vinegar and baking soda – bubbles of carbon dioxide form

42. Formation of a Precipitate Any solid that forms and separates from a liquid mixture is called a precipitate. Ex: when acid is added to milk, proteins in the milk undergo a chemical change that alters their structure, causing them to stick together in clumps

43. Is a change chemical or physical? When matter undergoes a chemical change, the composition of matter changes. When matter undergoes a physical change, the composition of the matter remains the same.

44. Beaker Breaker!! 1.) What is one of the three common types of evidence of a chemical change? 2.) Any solid that forms and separates from a liquid mixture is called a__________ 3.) Gasoline and paper is an example of what chemical property?