Chapter two powerpoint
- 1. Chapter 2 Nina Bartell 8-3
- 2. 2.1
- 3. Pure Substance 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 can be classified into two categories-elements and compounds
- 4. Elements and Atoms a substance that cannot be broken down into simpler substances an atom is the smallest particle of an element *an element has a fixed composition because it contains only one type of atom no two elements contain the same type of atom
- 5. Compounds a 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
- 6. Mixture *the properties of a mixture can vary because the composition of a mixture is not fixed mixtures can be classified by how well the parts of the mixture are distributed throughout the mixture
- 7. Heterogeneous and homogenous mixtures Heterogeneous: the parts of a mixture are noticeably different from one another (sand) Homogenous: the substances are so evenly distributed that it is difficult to distinguish one substance from another(serving spoon-iron, chromium, and nickel)
- 8. Solutions/Suspensions/Colloids *Based on the size of its largest particles, a mixture can be classified as a solution, suspension, or colloid Solution: when substances dissolve and form a homogenous mixture Able to see through solutions that are liquids because light passes through them without going in all different directions Suspension: heterogeneous mixture that separates into layers over time
- 9. 2.2
- 10. Physical Properties Any characteristic of a material that can be observed or measured without changing the composition of the substances in the material Used to identify a material, to choose a material for a specific purpose, or to separate the substances in a mixture viscosity, conductivity, malleability, hardness, melting point, boiling point, and density are all
- 11. Viscosity The tendency of a liquid to keep from flowing, it’s resistance to flowing Honey has a high viscosity because it is very resistant but water has a low viscosity because it is not very resistant
- 12. Conductivity A material’s ability to allow heat to flow would you use a metal or wooden spoon while stirring soup? A wooden one because it has low conductivity so the top of the spoon doesn’t get hot and it won’t burn you
- 13. Malleability The ability of a solid to be hammered without shattering Gold is malleable because when hammered, it doesn’t shatter but an ice cube is not because if hammered, it would shatter Most metals are malleable
- 14. Melting point Temperature at which a substance changes from a solid to a liquid Melting point for water is 0˚c at sea level
- 15. Boiling Point Temperature at which a substance boils Boiling point for water is 100˚c at sea level
- 16. Density Used to test the purity of a substance Ratio of the mass of a substance to its volume
- 17. Identifying a Material 1. Decide which properties to test 2. Do tests on the sample of the unknown 3. Compare the results with the data reported for known materials
- 18. What are Properties? They determine which materials are chosen for what uses
- 19. Filtration and Distillation These two terms are common separation methods Filtration: a process that separates materials based on the size of their particles Distillation: a process that separates the substances in a solution based on their boiling points
- 20. What is physical change? The change of water from a liquid to a gas during boiling This occurs when some of the properties of the material change but the substances in the material stay the same
- 21. Ways of Separating a Mixture Distillation Filtration Evaporation
- 22. Distillation A process that separates two substances in a solution based on their boiling points Distillation Apparatus Unknown Substance Alcohol Burner
- 23. Filtration A process that separates materials based on the size of particles +/or solubility filter paper goes inside filter the mixture is poured into filter paper the element left in the filter paper is the substance and the liquid at the bottom is to purified water (liquid)
- 24. Evaporation A process used to isolate a solid dissolved in a liquid ex: NaCl+water Disclaimer: water(liquid) will evaporate+you won’t be able to isolate a sample of it mixture is poured into an evaporating dish which is heated and all that is left is the dissolved element that is now not dissolved
- 25. 2.3
- 26. Chemical Property Any ability to produce a change in composition of matter Changes the composition of the substance *Chemical properties can only be observed when the substances in a sample of matter are changing into different substances
- 27. Flammability A material’s ability to burn in the presence of oxygen Example: alcohol and water
- 28. Reactivity A property that describes how readily a substance combines with other substances. Example: Oxygen/Potassium
- 29. Chemical Change Occurs when a substance reacts and forms one or more new substances *Three common types of of a chemical change: -change in color -the production of gas -the formation of a precipitate
- 30. Precipitate Any solid that forms and separates from a liquid mixture
- 31. REVIEW QUESTIONS
- 32. #1 QUESTION HOW MANY CATEGORIES ARE PURE SUBSTANCES CLASSIFIED INTO? AND WHAT ARE THOSE CATEGORIES?
- 33. #2 QUESTION WHAT TYPE OF CHANGE DO YOU USE WHEN YOU WANT THE COMPOSITION OF THE SUBSTANCES TO STAY THE SAME?
- 34. #3 QUESTION WHAT TECHNIQUE WOULD YOU USE TO ISOLATE A SOLUTION OF SALT AND WATER?
- 35. #4 QUESTION IF BLUE DYE WAS SPILLED ON A SHIRT, WOULD IT BE A CHEMICAL OR PHYSICAL CHANGE? WHY?
- 36. ANSWERS: #1- Pure substances are classified into two categories, elements and compounds. #2-You would use a physical change if you wanted the composition of the substances to stay the same. #3-The technique used to isolate a solution of salt and water would be evaporation. #4-It would be a chemical change if blue dye was spilled on a shirt because it changes the color, but also, it can never come out therefore it adds to the object.