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CHAPTER 2

CHAPTER 2. PROPERTIES OF MATTER. SECTION 1 CLASSIFYING MATTER. BASED ON COMPOSITIONS, MATERIALS CAN BE DIVIDED INTO PURE SUBSTANCES OR MIXTURES. SECTION 1 CLASSIFYING MATTER. PURE SUBSTANCE – matter that always has exactly the same composition

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CHAPTER 2

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  1. CHAPTER 2 PROPERTIES OF MATTER

  2. SECTION 1CLASSIFYING MATTER • BASED ON COMPOSITIONS, MATERIALS CAN BE DIVIDED INTO PURE SUBSTANCES OR MIXTURES.

  3. SECTION 1CLASSIFYING MATTER • PURE SUBSTANCE – matter that always has exactly the same composition • EVERY SAMPLE OF A GIVEN SUBSTANCE HAS THE SAME PROPERTIES BECAUSE A SUBSTANCE HAS A FIXED, UNIFORM COMPOSITION.

  4. SECTION 1CLASSIFYING MATTER • SUBSTANCES CAN BE CLASSIFIED INTO TWO CATEGORIES – ELEMENTS AND COMPOUNDS.

  5. SECTION 1CLASSIFYING MATTER • ELEMENT – an element is a substance that cannot be broken down into simpler substances • AN ELEMENT HAS A FIXED COMPOSITION BECAUSE IT CONTAINS ONLY ONE TYPE OF ATOM. • NO TWO ELEMENTS CONTAIN THE SAME TYPE OF ATOM.

  6. SECTION 1CLASSIFYING MATTER • EXAMPLES OF ELEMENTS • AT ROOM TEMPERATURE MOST ELEMENTS ARE SOLIDS SUCH AS ALUMINUM AND CARBON. • GOLD (Au) • ALUMINUM (Al) • CARBON (C) • IODINE (I)

  7. SECTION 1CLASSIFYING MATTER • SYMBOLS FOR ELEMENTS • IN 1813 Jons Berzelius suggested that chemists use symbols to represent elements. • EACH SYMBOL HAS ONE OR TWO LETTERS • THE FIRST LETTER IS ALWAYS CAPITALIZED • THE SECOND LETTER IS ALWAYS LOWER CASE

  8. SECTION 1CLASSIFYING MATTER • COMPOUNDS – SUBSTANCE THAT IS MADE FROM TWO OR MORE SIMPLER SUBSTANCES AND CAN BE BROKEN DOWN INTO THOSE SIMPLER SUBSTANCES. • THE SIMPLER SUBSTANCES ARE EITHER ELEMENTS OR OTHER COMPOUNDS • THE PROPERTIES OF A COMPOUND DIFFER FROM THOSE OF THE SUBSTANCES FROM WHICH IT IS MADE • EX. WATER (H2O)

  9. SECTION 1CLASSIFYING MATTER • A COMPOUND ALWAYS CONTAINS TWO OR MORE ELEMENTS JOINED IN A FIXED PROPORTION. • IF THE PROPORTION CHANGES THEN THE COMPOUND CHANGES.

  10. SECTION 1CLASSIFYING MATTER • MIXTURES • MIXTURES RETAIN SOME OF THE PROPERTIES OF THEIR INDIVIDUAL SUBSTANCES • THE PROPERTIES OF A MIXTURE ARE LESS CONSTANT THAN THE PROPERTIES OF A SUBSTANCE. • THE PROPERTIES OF A MIXTURE CAN VARY BECAUSE THE COMPOSITION OF A MIXTURE IS NOT FIXED

  11. SECTION 1CLASSIFYING MATTER • MIXTURES cont. • THERE ARE 2 TYPES OF MIXTURES • HETEROGENEOUS MIXTURES • HOMOGENEOUS MIXTURES

  12. SECTION 1CLASSIFYING MATTER • HETEROGENEOUS MIXTURE • THE PARTS OF THE MIXTURE ARE NOTICEABLY DIFFERENT FROM ONE ANOTHER • EX. SAND

  13. SECTION 1CLASSIFYING MATTER • HOMOGENEOUS MIXTURES • THE SUBSTANCES ARE EVENLY DISTRIBUTED THAT IT IS DIFFICULT TO DISTINGUISH ONE SUBSTANCE IN THE MIXTURE FROM ANOTHER. • HOMOGENEOUS MIXTURES APPEAR TO CONTAIN ONLY ONE SUBSTANCE. • EX. WATER IN SWIMMING POOL

  14. SECTION 1CLASSIFYING MATTER • SOLUTIONS, SUSPENSIONS, AND COLLOIDS • BASED ON THE SIZE OF ITS LARGEST PARTICLE, A MIXTURE CAN BE CLASSIFIED AS A SOLUTION, A SUSPENSION, OR A COLLOID.

  15. SECTION 1CLASSIFYING MATTER • SOLUTIONS – SUBSTANCES THAT DISSOLVE AND FORM A HOMOGENEOUS MIXTURE • SOLUTIONS DO NOT SEPARATE INTO LAYERS OVER TIME. • EX. • WIPER FLUID • TAP WATER

  16. SECTION 1CLASSIFYING MATTER • SUSPENSIONS – HETEROGENEOUS MIXTURE THAT SEPARATES INTO LAYERS OVER TIME. • SUSPENDED PARTICLES SETTLE OUT OF A MIXTURE OR ARE TRAPPED BY A FILTER BECAUSE THEY ARE LARGER THAN THE PARTICLES IN A SOLUTION. • EX. • MUDDY WATER

  17. SECTION 1CLASSIFYING MATTER • COLLOID – CONTAINS SOME PARTICLES THAT ARE INTERMEDIATE IN SIZE BETWEEN THE SMALL PARTICLES IN A SOLUTION AND THE LARGER PARTICLES IN A SUSPENSION. • THEY DO NOT SEPARATE INTO LAYERS • CANNOT USE A FILTER TO SEPARATE THE PARTS OF A COLLOID • EX. • FOG IN THE AIR

  18. SECTION 2PHYSICAL PROPERTIES • VISCOSITY, CONDUCTIVITY, MALLEABILITY, HARDNESS, MELTING POINT, BOILING POINT, AND DENSITY ARE EXAMPLES OF PHYSICAL PROPERTIES.

  19. SECTION 2PHYSICAL PROPERTIES • VISCOSITY – THE TENDENCY OF A LIQUID TO KEEP FROM FLOWING, ITS RESISTANCE TO FLOWING. • THE GREATER THE VISCOSITY THE SLOWER IT MOVES. • VISCOSITY DECREASES WHEN HEATED • VISCOSITY INCREASES WHEN COOLED

  20. SECTION 2PHYSICAL PROPERTIES • CONDUCTIVITY – MATERIALS ABILITY TO ALLOW HEAT TO FLOW • MATERIALS THAT HAVE A HIGH CONDUCTIVITY SUCH AS METALS ARE CALLED CONDUCTORS. • GOOD CONDUCTOR OF HEAT = GOOD CONDUCTOR OF ELECTRICITY

  21. SECTION 2PHYSICAL PROPERTIES • MALLEABILITY – ABILITY OF A SOLID TO BE HAMMERED WITHOUT SHATTERING. • MOST METALS ARE MALLEABLE • EX. GOLDSMITHS, BLACKSMITHS • BY CONTRAST, ICE WILL SHATTER WHEN HIT WITH HAMMER.

  22. SECTION 2PHYSICAL PROPERTIES • HARDNESS – THE ABILITY OF ONE MATERIAL TO SCRATCH ANOTHER • STAINLESS STEEL IS HARDER THAN COPPER • DIAMOND IS THE HARDEST KNOWN MATERIAL

  23. SECTION 2PHYSICAL PROPERTIES • MELTING POINT – THE TEMPERATURE AT WHICH A SUBSTANCE CHANGES FROM A SOLID TO LIQUID • EX. • ICE MELTING TO WATER

  24. SECTION 2PHYSICAL PROPERTIES • BOILING POINT – THE TEMPERATURE AT WHICH A SUBSTANCE BOILS. • SOME SUBSTANCES CHANGE FROM A LIQUID TO A GAS AT THIS POINT

  25. SECTION 2PHYSICAL PROPERTIES • DENSITY – MASS OF AN OBJECT DIVIDED BY ITS VOLUME • D=M/V • DENSITY CAN BE USED TO TEST THE PURITY OF A SUBSTANCE.

  26. SECTION 2PHYSICAL PROPERTIES • PHYSICAL PROPERTIES ARE USED TO IDENTIFY A MATERIAL ,TO CHOOSE A MATERIAL FOR A SPECIFIC PURPOSE, OR TO SEPARATE THE SUBSTANCE IN A MIXTURE.

  27. SECTION 2PHYSICAL PROPERTIES • USING PROPERTIES TO IDENTIFY MATERIALS • STEP 1: DECIDE WHICH PROPERTIES TO TEST • EX. DENSITY, MASS, MELTING POINT, BOILING POINT, ETC. • STEP 2: TEST THE UNKOWN SAMPLE • FINAL STEP: COMPARE THE RESULTS WITH THE DATA REPORTED FOR KNOWN MATERIALS

  28. SECTION 2PHYSICAL PROPERTIES • USING PROPERTIES TO CHOOSE MATERIALS • PROPERTIES DETERMINE WHICH MATERIALS ARE CHOSEN FOR WHICH USES. • WOODEN SHOELACES • METAL TIRES • PAPER CHAINS

  29. SECTION 2PHYSICAL PROPERTIES • USING PROPERTIES TO SEPARATE MATERIALS • FILTRATION AND DISTILLATION ARE TWO COMMON SEPARATION METHODS.

  30. SECTION 2PHYSICAL PROPERTIES • FILTRATION – PROCESS THAT SEPARATES MATERIALS BASED ON THE SIZE OF THEIR PARTICLES. • EX. COFFEE FILTERS FILTER COFFEE GRAINS BUT ALLOW CAFFIENE AND SMALLER COFFEE GRAINS TO PASS THROUGH

  31. SECTION 2PHYSICAL PROPERTIES • DISTILLATION – PROCESS THAT SEPARATES SUBSTANCES IN A SOLUTION BASED ON THEIR BOILING POINTS. • EX. BOILING SEA WATER, CAPTURING THE WATER VAPORS, COOLING THE VAPORS AND COLLECTING THEM IN A SEPARATE CONTAINER…THIS PROVIDES FRESH WATER WITHOUT THE SALT.

  32. SECTION 2PHYSICAL PROPERTIES • RECOGNIZING PHYSICAL CHANGES • A PHYSICAL CHANGE OCCURS WHEN SOME OF THE PROPERTIES OF A MATERIAL CHANGE, BUT THE SUBSTANCES IN THE MATERIAL REMAIN THE SAME. • EX. METLING BUTTER IN A PAN CAUSES THE BUTTER TO CHANGE FROM A SOLID TO A LIQUID BUT THE SUBSTANCES IN THE BUTTER DO NOT CHANGE. • SOME PHYSICAL CHANGES CAN BE REVERSED AND SOME CANNOT. • EX. MELTING ICE AND REFREEZING IT (REVERSED) • EX. REPLACING THE PEELING ON AN ORANGE AFTER YOU PEELED IT. (IRREVERSIBLE)

  33. SECTION 3CHEMICAL PROPERTIES • CHEMICAL PROPERTY – THE ABILITY TO PRODUCE A CHANGE IN THE COMPOSITION OF MATTER. • EX. THE ABILITY TO BURN. • CHEMICAL PROPERTIES CAN BE OBSERVED ONLY WHEN THE SUBSTANCE IN A SAMPLE OF MATTER ARE CHANGING INTO DIFFERENT SUBSTANCES.

  34. SECTION 3CHEMICAL PROPERTIES • FLAMABILITY – MATERIAL ABILITY TO BURN IN THE PRESENCE OF OXYGEN • REACTIVITY – THE PROPERTY THAT DESCRIBES HOW READILY A SUBSTANCE COMBINES CHEMICALLY WITH OTHER SUBSTANCES

  35. SECTION 3CHEMICAL PROPERTIES • RECOGNIZING CHEMICAL CHANGES • A CHEMICAL CHANGE OCCURS WHEN A SUBSTANCE REACTS AND FORMS ONE OR MORE NEW SUBSTANCES. • EX. CAKE BAKING IN THE OVEN, LEAVES ON A TREE CHANGING COLORS

  36. SECTION 3CHEMICAL PROPERTIES • RECOGNIZING CHEMICAL CHANGE • THREE COMMON TYPES OF EVIDENCE FOR A CHEMICAL CHANGE ARE A CHANGE IN COLOR, THE PRODUCTION OF A GAS, AND THE FORMATION OF A PRECIPITATE.

  37. SECTION 3CHEMICAL PROPERTIES • A CHANGE IN COLOR • SILVER WILL DARKEN WHEN EXPOSED TO AIR • COPPER WILL CHANGE COLORS (COPPER TO GREEN) • A CHANGE IN COLOR IS A CLUE THAT A CHEMICAL CHANGE HAS PRODUCED AT LEAST ONE NEW SUBSTANCE.

  38. SECTION 3CHEMICAL PROPERTIES • PRODUCTION OF GAS • IF THE COMBINATION OF TWO OR MORE SUBSTANCES PRODUCES A GAS A CHEMICAL CHANGE IS HAPPENING. • EX. CARBONATION FIZZING IN SOFT DRINKS, BAKING SODA AND VINEGAR

  39. SECTION 3CHEMICAL PROPERTIES • FORMATION OF A PRECIPITATE • HAPPENS WHEN A SOLID FORMS AND SEPARATES OUT OF A LIQUID. • EX. ADDING ACID TO MILK WILL CAUSE THE PROTEIN IN MILK TO CLUMP TOGETHER.

  40. SECTION 3CHEMICAL PROPERTIES • HOW TO DETERMINE IF A CHANGE IS CHEMICAL OR PHYSICAL: • WHEN MATTER UNDERGOES A CHEMICAL CHANGE, THE COMPOSITION OF HE MATTER CHANGES; WHEN MATTER UNDERGOES A PHYSICAL CHANGE, THE COMPOSITION OF THE MATTER REMAINS THE SAME.

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