This document summarizes key concepts from a chapter on matter, including: - Distinguishing between physical and chemical properties and changes - Defining the three physical states of matter - Explaining conservation of mass in chemical reactions - Contrasting mixtures and pure substances - Describing techniques to separate mixtures - Distinguishing between elements and compounds - Explaining the organization of the periodic table and laws of definite and multiple proportions governing compounds

1. Matter- Properties and Changes Chapter 3 Review

2. Ch 3 Objectives Distinguish between physical and chemical properties. Differentiate among the physical states of matter. Define physical change and list several common physical changes. Define chemical change and list several indications that a chemical change has taken place. Apply the law of conservation of mass to chemical reactions. Contrast mixtures and substances. Classify mixtures as homogeneous or heterogeneous. List and describe several techniques used to separate mixtures. Distinguish between elements and compounds. Describe the organization of elements on the periodic table. Explain how all compounds obey the law of definite and multiple proportions.

3. Demo Step 1 Hydrochloric acid (HCl) is dissolved in water to a concentration of 1.5 Molar. About 10 mL of the HCl solution is placed in a flask.

4. Describe HCl (aq) Water is a liquid HCl and H 2 O form a homogeneous mixture or solution - written as HCl (aq) When HCl mixes with water to make a solution, HCl and H 2 O still have their original chemical properties and composition Therefore this is a physical change !

5. A = Physical Property B = Chemical Property HCl is soluble in water physical property HCl is corrosive to metals chemical property HCl burns skin chemical property

6. Homework Check #2 A = physical property B = chemical property 2a) 2b) 2c) 2d) 2e) Chemical Physical Chemical Physical Physical

7. What are elements and compounds? HCl made of H and Cl on periodic table H and Cl are both nonmetallic elements H and Cl combine to form a compound H 2 O Is a compound (pure substance) also made of the nonmetals H and O Always in ratio of 2:1 to form water

8. What is matter? Element Zn cannot be separated made of atoms Compound H 2 O separate by chemical change made of molecules Mixture HCl(aq) separate by physical change made of atoms/molecules

9. Demo Step 2 Measure the mass of a piece of zinc. Add the piece of zinc metal to a balloon. Stretch the balloon over the mouth of the flask.

10. What are metals? Metals are elements on the left side of the periodic table Physical properties – Shiny Conduct electricity Malleable Ductile Solid These are intensive properties – independent of amount

11. Mass of zinc = ___________________ g This is an extensive physical property – depends on amount Zinc is an element (which is a pure substance) is a metal is a solid

12. Demo Step 3 Take the mass of the system = ________ g Add Zn to HCl (aq) Retake the mass of the system = ________ g

13. What are chemical changes? A chemical change occurred… Evidence of chemical change and new substances formed: gas given off color change heat evolved Notice HCl still had the ability to corrode metals even though in solution with water

14. What happens to mass? Mass does not change during a reaction ; although substances do change Mass reactants = Mass products Zn(s) + 2HCl(aq)  ZnCl 2 (aq) + H 2 (g) Hydrogen gas should be formed New substance Different properties from reactants!

15. Homework Check #6 10.0 g 69.4 g 79.4 g 89.4 g Not enough info

16. Homework #7  B or better! Chlorine 15.6 g 24.1 g 39.7 g 55.3 g Sodium 15.6 g 24.1 g 39.7 g 55.3 g

17. Demo Step 4 Check to see if hydrogen gas IS in balloon… HOW? Hydrogen gas is EXPLOSIVE!!!!! This is a chemical property… So we’ll have to carry out the chemical change to test!

18. Ch 3 Objectives Distinguish between physical and chemical properties. Differentiate among the physical states of matter. Define physical change and list several common physical changes. Define chemical change and list several indications that a chemical change has taken place. Apply the law of conservation of mass to chemical reactions. Contrast mixtures and substances. Classify mixtures as homogeneous or heterogeneous. List and describe several techniques used to separate mixtures. Distinguish between elements and compounds. Describe the organization of elements on the periodic table. Explain how all compounds obey the law of definite and multiple proportions.

19. Properties Distinguish between physical and chemical properties. Physical Property – a characteristic that can be observed or measured without changing the sample’s composition Chemical Property – the ability of a substance to combine with or change into one or more other substances

20. States of Matter Differentiate among the physical states of matter. Solid = a form of matter that has its own definite shape and volume Liquid = flows, has its own volume, but takes shape of container Gas = flows to conform to the shape of its container AND fills the entire volume of its container

21. Physical Changes Physical change = a change which alters a substance without changing its composition Examples: Cutting Bending Melting Freezing Condensing Vaporizing Boiling Define physical change and list several common physical changes.

22. Chemical Changes Define chemical change and list several indications that a chemical change has taken place. Chemical change – involves a change in a substance’s composition Chemical reaction – alternate name! Reactants  Products (  = “form”) Evidence of chemical change: Light, heat or sound given off Color or odor change Precipitate (solid) or gas formation

23. Law of Conservation of Mass Apply the law of conservation of mass to chemical reactions. Mass is neither created nor destroyed during a chemical reaction Mass is conserved! Mass reactants = Mass products

24. Mixtures vs. Substances Contrast mixtures and substances. Substance – matter that has a uniform and unchanging composition Mixture – a combination of two or more pure substances (in any proportion) in which each pure substance retains its individual chemical properties; can be broken down by physical means (changes) SEE FIG 3-17

25. Mixtures Classify mixtures as homogeneous or heterogeneous. Heterogeneous mixture – one that does not blend smoothly throughout and in which the individual substances remain distinct Homogeneous mixture – has constant composition throughout; always has a single phase Solutions – alternate name! SEE FIG 3-17

26. Homework Check #17 A = heterogeneous mixture B = homogeneous mixture 17. a) 17. b) 17. c) 17. d) 17. e) A B B B A

27. Mixture Separation Techniques List and describe several techniques used to separate mixtures. Filtration – a technique that uses a porous barrier to separate a solid from a liquid (fig 3-15) Distillation – a separation technique based on differences in the boiling points of the substances involved  “distilled water”

28. Mixture Separation Techniques (cont’d) List and describe several techniques used to separate mixtures. Crystallization – a separation technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance  ex) making sugar candy Chromatography – a technique that separates the components of a mixture (called the mobile phase) on the basis of the tendency of each to travel or be drawn across the surface of another material (called the stationary phase)  your minilab!

29. Homework #19  B or better! Filtration Distillation Crystallization Chromatography None of the above 19. a) 19. b) 19. c)

30. Substances Distinguish between elements and compounds. Element – a pure substance that cannot be separated into simpler substances by physical or chemical means Compound – a chemical combination of two or more different elements with properties of its own; can be broken down into simpler substances by chemical means SEE FIG 3-17

31. Elements Describe the organization of elements on the periodic table . Periodic Table – organizes the elements into a grid of horizontal rows called periods and vertical columns called groups (families) Metals – on the left side of the stairstep Nonmetals – to the right of the stairstep Elements are organized in repeating patterns of properties; elements in the same group have similar properties

32. Homework #29  B or better Potassium Nitrogen Sodium Calcium Sulfur Krypton Bromine Arsenic Boron Argon

33. Compounds Explain how all compounds obey the laws of definite and multiple proportions. Law of definite proportions – a compound is always composed of the same elements in the same proportion by mass Law of multiple proportions – when different compounds are formed by a combination of the same elements, different masses of one element combine with the same relative mass of the other element in a ratio of small whole numbers

34. What? Definite Proportions Water is always 2 g hydrogen to 16 g oxygen Also can think of as 2 H atoms to 1 O atom Multiple Proportions H and O can combine to make 2 different compounds: water and hydrogen peroxide Water = H 2 O Hydrogen Peroxide = H 2 O 2 Same elements, but different WHOLE number ratios; mass of oxygen in H 2 O:H 2 O 2 is 1:2

35. Homework Check #23 Yes No

36. Homework Check #28 Compounds containing the same elements Compounds containing different elements Mixtures containing the same elements Mixtures containing different elements

37. Ch 3 Objectives Distinguish between physical and chemical properties. Differentiate among the physical states of matter. Define physical change and list several common physical changes. Define chemical change and list several indications that a chemical change has taken place. Apply the law of conservation of mass to chemical reactions. Contrast mixtures and substances. Classify mixtures as homogeneous or heterogeneous. List and describe several techniques used to separate mixtures. Distinguish between elements and compounds. Describe the organization of elements on the periodic table. Explain how all compounds obey the law of definite and multiple proportions.