Introductory Chemistry , 3 rd Edition Nivaldo Tro

1. Introductory Chemistry, 3rd EditionNivaldo Tro Chapter 3 Matter and Energy Basic Principles of Chemistry Online Southeast Missouri State University Cape Girardeau, MO 2009, Prentice Hall

2. In Your Room • Everything you can see, touch, smell or taste in your room is made of matter. • Chemists study the differences in matter and how that relates to the structure of matter. Tro's "Introductory Chemistry", Chapter 3

3. What Is Matter? • Matter is defined as anything that occupies space and has mass. • Even though it appears to be smooth and continuous, matter is actually composed of a lot of tiny little pieces we call atoms and molecules. Tro's "Introductory Chemistry", Chapter 3

4. Atoms and Molecules • Atoms are the tiny particles that make up all matter. • In most substances, the atoms are joined together in units called molecules. • The atoms are joined in specific geometric arrangements. Tro's "Introductory Chemistry", Chapter 3

5. Carbon Dioxide Carbon Monoxide • Composed of one carbon atom and two oxygen atoms. • Colorless, odorless gas. • Incombustible. • Does not bind to hemoglobin. • Composed of one carbon atom and one oxygen atom. • Colorless, odorless gas. • Burns with a blue flame. • Binds to hemoglobin. Structure Determines Properties • The properties of matter are determined by the atoms and molecules that compose it.

6. Classifying Matterby Physical State • Matter can be classified as solid, liquid, or gas based on what properties it exhibits. • Fixed = Property doesn’t change when placed in a container. • Indefinite = Takes the property of the container. Tro's "Introductory Chemistry", Chapter 3

7. Structure Determines Properties • The atoms or molecules have different structures in solids, liquids, and gases − leading to different properties.

8. Solids • The particles in a solid are packed close together and are fixed in position. • Although they may vibrate. • The close packing of the particles results in solids being incompressible. • The inability of the particles to move around results in solids retaining their shape and volume when placed in a new container and prevents the particles from flowing. Tro's "Introductory Chemistry", Chapter 3

9. Solids, Continued • Some solids have their particles arranged in an orderly geometric pattern—we call these crystalline solids. • Salt and diamonds. • Other solids have particles that do not show a regular geometric pattern over a long range—we call these amorphous solids. • Plastic and glass. Tro's "Introductory Chemistry", Chapter 3

10. Liquids • The particles in a liquid are closely packed, but they have some ability to move around. • The close packing results in liquids being incompressible. • The ability of the particles to move allows liquids to take the shape of their container and to flow. However, they don’t have enough freedom to escape and expand to fill the container. Tro's "Introductory Chemistry", Chapter 3

11. Gases • In the gas state, the particles have complete freedom from each other. • The particles are constantly flying around, bumping into each other and the container. • In the gas state, there is a lot of empty space between the particles. • On average. Tro's "Introductory Chemistry", Chapter 3

12. Gases, Continued • Because there is a lot of empty space, the particles can be squeezed closer together. Therefore, gases are compressible. • Because the particles are not held in close contact and are moving freely, gases expand to fill and take the shape of their container, and will flow. Tro's "Introductory Chemistry", Chapter 3

13. Classification of Matter by Appearance • Homogeneous = Matter that is uniform throughout. • Appears to be one thing. • Every piece of a sample has identical properties, though another sample with the same components may have different properties. • Solutions (homogeneous mixtures) and pure substances. • Heterogeneous = Matter that is non-uniform throughout . • Contains regions with different properties than other regions. Tro's "Introductory Chemistry", Chapter 3

14. Practice—Classify the Following as Homogeneous or Heterogeneous • Table sugar. • A mixture of table sugar and black pepper. • A mixture of sugar dissolved in water. • Oil and vinegar salad dressing. Tro's "Introductory Chemistry", Chapter 3

15. Practice—Classify the Following as Homogeneous or Heterogeneous, Continued • Table sugar =homogeneous • A mixture of table sugar and black pepper = heterogeneous • A mixture of sugar dissolved in water = homogeneous • Oil and vinegar salad dressing = heterogeneous Tro's "Introductory Chemistry", Chapter 3

16. Classifying Matterby Composition • Matter that is composed of only one kind of atom or molecule is called a pure substance. • Matter that is composed of different kinds of atoms or molecules is called a mixture. • Because pure substances always have only one kind of piece, all samples show the same properties. • However, because mixtures have variable composition, different samples will show different properties. Tro's "Introductory Chemistry", Chapter 3

17. Copper—A Pure Substance • Color is brownish red. • Shiny, malleable, and ductile. • Excellent conductor of heat and electricity. • Melting point = 1084.62 °C • Density = 8.96 g/cm3 at 20 °C Tro's "Introductory Chemistry", Chapter 3

18. Brass—A Mixture

19. Matter Pure Substance Mixture Constant Composition Variable Composition Homogeneous Classification of Matter • Pure Substance = All samples are made of the same pieces in the same percentages. • Salt • Mixtures= Different samples may have the same pieces in different percentages. • Salt water Tro's "Introductory Chemistry", Chapter 3

20. Pure Substances 1. All samples have the same physical and chemical properties. 2. Constant composition = All samples have the same pieces in the same percentages. 3. Homogeneous. 4. Separate into components based on chemical properties. 5. Temperature stays constant while melting or boiling. Mixtures 1. Different samples may show different properties. 2. Variable composition = Samples made with the same pure substances may have different percentages. 3. Homogeneous or heterogeneous. 4. Separate into components based on physical properties. 5. Temperature usually changes while melting or boiling because composition changes. Pure Substances vs. Mixtures Tro's "Introductory Chemistry", Chapter 3

21. Practice—Classify the Following as Pure Substances or Mixtures • A homogeneous liquid whose temperature stays constant while boiling. • Granite—a rock with several visible minerals in it. • A red solid that turns blue when heated and releases water that is always 30% of the solid’s mass. • A gas that when cooled and compressed, a liquid condenses out but some gas remains. Tro's "Introductory Chemistry", Chapter 3

22. Practice—Classify the Following as Pure Substances or Mixtures, Continued • A homogeneous liquid whose temperature stays constant while boiling = pure substance. • Granite—a rock with several visible minerals in it = mixture. • A red solid that turns blue when heated and releases water that is always 30% of the solid’s mass = pure substance. • A gas that when cooled and compressed, a liquid condenses out but some gas remains = mixture. Tro's "Introductory Chemistry", Chapter 3

23. Classification of Pure Substances • Substances that cannot be broken down into simpler substances by chemical reactions are called elements. • Basic building blocks of matter. • Composed of single type of atom. • Although those atoms may or may not be combined into molecules. • Substances that can be decomposed are called compounds. • Chemical combinations of elements. • Although properties of the compound are unrelated to the properties of the elements in it! • Composed of molecules that contain two or more different kinds of atoms. • All molecules of a compound are identical, so all samples of a compound behave the same way. • Most natural pure substances are compounds. Tro's "Introductory Chemistry", Chapter 3

24. Atoms and Molecules • Atoms • Are submicroscopic particles that are the unit pieces of elements. • Are the fundamental building blocks of all matter. • Molecules • Are submicroscopic particles that are the unit pieces of compounds. • Two or more atoms attached together. • Attachments are called bonds. • Attachments come in different strengths. • Molecules come in different shapes and patterns. Tro's "Introductory Chemistry", Chapter 3

25. Classification of Pure Substances Elements Compounds 1. Made of one type of atom. (Some elements are found as multi-atom molecules in nature.) 2. Combine together to make compounds. 1. Made of one type of molecule, or array of ions. 2. Molecules contain 2 or more different kinds of atoms. Tro's "Introductory Chemistry", Chapter 3

26. Practice—Classify the Following as Elements or Compounds • Chlorine, Cl2 • Table sugar, C12H22O11 • A red solid that turns blue when heated and releases water that is always 30% of the solid’s mass. • A brown-red liquid that, when energy is applied to it in any form, causes only physical changes in the material, not chemical. Tro's "Introductory Chemistry", Chapter 3

27. Practice—Classify the Following as Elements or Compounds, Continued • Chlorine, Cl2 = element. • Table sugar, C12H22O11 = compound. • A red solid that turns blue when heated and releases water that is always 30% of the solid’s mass = compound. • A brown-red liquid that, when energy is applied to it in any form, causes only physical changes in the material, not chemical = element. Tro's "Introductory Chemistry", Chapter 3

28. Classification of Mixtures • Mixtures are generally classified based on their uniformity. • Mixtures that are uniform throughout are called homogeneous. • Also known as solutions. • Mixing is on the molecular level. • Mixtures that have regions with different characteristics are called heterogeneous. Tro's "Introductory Chemistry", Chapter 3

29. Classification of Mixtures, Continued Heterogeneous Homogeneous 1. Made of multiple substances, whose presence can be seen. 2. Portions of a sample have different composition and properties. 1. Made of multiple substances, but appears to be one substance. 2. All portions of a sample have the same composition and properties. Tro's "Introductory Chemistry", Chapter 3

30. Classifying Matter

31. Properties Distinguish Matter • Each sample of matter is distinguished by its characteristics. • The characteristics of a substance are called its properties. • Some properties of matter can be observed directly. • Other properties of matter are observed when it changes its composition. Tro's "Introductory Chemistry", Chapter 3

32. Properties of Matter • Physical Properties are the characteristics of matter that can be changed without changing its composition. • Characteristics that are directly observable. • Chemical Properties are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy. • Characteristics that describe the behavior of matter. Tro's "Introductory Chemistry", Chapter 3

33. Some Physical Properties Tro's "Introductory Chemistry", Chapter 3

34. Some Physical Properties of Iron • Iron is a silvery solid at room temperature with a metallic taste and smooth texture. • Iron melts at 1538 °C and boils at 4428 °C. • Iron’s density is 7.87 g/cm3. • Iron can be magnetized. • Iron conducts electricity, but not as well as most other common metals. • Iron’s ductility and thermal conductivity are about average for a metal. • It requires 0.45 J of heat energy to raise the temperature of one gram of iron by 1°C. Tro's "Introductory Chemistry", Chapter 3

35. Some Chemical Properties Tro's "Introductory Chemistry", Chapter 3

36. Some Chemical Properties of Iron • Iron is easily oxidized in moist air to form rust. • When iron is added to hydrochloric acid, it produces a solution of ferric chloride and hydrogen gas. • Iron is more reactive than silver, but less reactive than magnesium. Tro's "Introductory Chemistry", Chapter 3

37. Practice—Decide Whether Each of the Observations About Table Salt Is a Physical or Chemical Property • Salt is a white, granular solid. • Salt melts at 801 °C. • Salt is stable at room temperature, it does not decompose. • 36 g of salt will dissolve in 100 g of water. • Salt solutions and molten salt conduct electricity. • When a clear, colorless solution of silver nitrate is added to a salt solution, a white solid forms. • When electricity is passed through molten salt, a gray metal forms at one terminal and a yellow-green gas at the other. Tro's "Introductory Chemistry", Chapter 3

38. Practice − Decide Whether Each of the Observations About Table Salt Is a Physical or Chemical Property • Salt is a white, granular solid = physical. • Salt melts at 801 °C = physical. • Salt is stable at room temperature, it does not decompose = chemical. • 36 g of salt will dissolve in 100 g of water = physical. • Salt solutions and molten salt conduct electricity = physical. • When a clear, colorless solution of silver nitrate is added to a salt solution, a white solid forms = chemical. • When electricity is passed through molten salt, a gray metal forms at one terminal and a yellow-green gas at the other = chemical. Tro's "Introductory Chemistry", Chapter 3

39. Changes in Matter • Changes that alter the state or appearance of the matter without altering the composition are called physical changes. • Changes that alter the composition of the matter are called chemical changes. • During the chemical change, the atoms that are present rearrange into new molecules, but all of the original atoms are still present. Tro's "Introductory Chemistry", Chapter 3

40. Changes in Matter, Continued • Physical Changes—Changes in the properties of matter that do not effect its composition. • Heating water. • Raises its temperature, but it is still water. • Evaporating butane from a lighter. • Dissolving sugar in water. • Even though the sugar seems to disappear, it can easily be separated back into sugar and water by evaporation. Tro's "Introductory Chemistry", Chapter 3

41. Changes in Matter, Continued • Chemical Changes involve a change in the properties of matter that change its composition. • A chemical reaction. • Rusting is iron combining with oxygen to make iron(III) oxide. • Burning results in butane from a lighter to be changed into carbon dioxide and water. • Silver combines with sulfur in the air to make tarnish. Tro's "Introductory Chemistry", Chapter 3

42. Is it a Physical or Chemical Change? • A physical change results in a different form of the same substance. • The kinds of molecules don’t change. • A chemical change results in one or more completely new substances. • Also called chemical reactions. • The new substances have different molecules than the original substances. • You will observe different physical properties because the new substances have their own physical properties. Tro's "Introductory Chemistry", Chapter 3

43. Phase Changes ArePhysical Changes • Boiling = liquid to gas. • Melting = solid to liquid. • Subliming = solid to gas. • Freezing = liquid to solid. • Condensing = gas to liquid. • Deposition = gas to solid. • State changes require heating or cooling the substance. • Evaporation is not a simple phase change, it is a solution process. Tro's "Introductory Chemistry", Chapter 3

44. Practice—Classify Each Change as Physical or Chemical • Evaporation of rubbing alcohol. • Sugar turning black when heated. • An egg splitting open and spilling out. • Sugar fermenting. • Bubbles escaping from soda. • Bubbles that form when hydrogen peroxide is mixed with blood. Tro's "Introductory Chemistry", Chapter 3

45. Practice—Classify Each Change as Physical or Chemical, Continued • Evaporation of rubbing alcohol = physical. • Sugar turning black when heated = chemical. • An egg splitting open and spilling out = physical. • Sugar fermenting = chemical. • Bubbles escaping from soda = physical. • Bubbles that form when hydrogen peroxide is mixed with blood = chemical. Tro's "Introductory Chemistry", Chapter 3

46. Different Physical Property Technique Boiling point Distillation State of matter (solid/liquid/gas) Filtration Adherence to a surface Chromatography Volatility Evaporation Density Centrifugation and decanting Separation of Mixtures • Separate mixtures based on different physical properties of the components. • Physical change. Tro's "Introductory Chemistry", Chapter 3

47. Distillation Tro's "Introductory Chemistry", Chapter 3

48. Filtration Tro's "Introductory Chemistry", Chapter 3

49. Law of Conservation of Mass • Antoine Lavoisier • “Matter is neither created nor destroyed in a chemical reaction.” • The total amount of matter present before a chemical reaction is always the same as the total amount after. • The total mass of all the reactants is equal to the total mass of all the products. Tro's "Introductory Chemistry", Chapter 3

50. Conservation of Mass • Total amount of matter remains constant in a chemical reaction. • 58 grams of butane burns in 208 grams of oxygen to form 176 grams of carbon dioxide and 90 grams of water. butane + oxygen  carbon dioxide + water 58 grams + 208 grams  176 grams + 90 grams 266 grams = 266 grams Tro's "Introductory Chemistry", Chapter 3