Chemistry Final Study Guide KEY Unit 2: Matter & Its Properties, Lesson 1: Physical and Chemical Properties & Changes 1. Define physical properties. The characteristics of a substance that can be observed without changing the identity of the substance. 2. Give three examples of physical properties. Color, shape, size, texture, volume, mass, density 3. Define physical changes. A change in any physical property of a substance, not in the substance itself. 4. What question should you ask yourself to determine if a physical change has occurred? (What would be the answer to that question in order for it to be a physical change?) Was a new substance formed? (No = physical change) 5. Give two examples of physical changes. Breaking the piece of clay; Stretching the rubber band 6. Define chemical properties. Describe how substance can form new substances. 7. Define chemical changes. The change of one substance into another substance. 8. What question should you ask yourself to determine if a chemical change has occurred? (What would be the answer to that question in order for it to be a chemical change?) Was a new substance formed? (Yes = chemical change) 9. Give two examples of chemical changes. A piece of wood burning; Iron fencing rusting; Silver spoon tarnishing; Cooking 10. What is the only true indication that a chemical change has occurred? A new substance was formed. 11. List the five signs that a chemical change may have occurred. Production of an odor; Change in temperature; Change in color; Formation of bubbles; Formation of a solid (precipitate) Unit 2: Matter & Its Properties, Lesson 2: States of Matter 12. What are the three main states of matter? Solid, liquid, gas 13. How can you tell the difference between the three states of matter?
14. When changing states of matter, are you observing a physical or chemical change? Why? Physical change because no new substance was formed. 15. Define melting. The process by which a solid becomes a liquid. 16. What is the melting point of ice? 0 C 17. Define freezing. The process by which a liquid becomes a solid. 18. What is the freezing point of water? 0 C 19. What is the difference between the melting point and freezing point? Explain. They are the same (0 C) however moving in opposite directions (melting = temperature increasing; freezing = temperature decreasing). 20. Define evaporation. A process by which a liquid becomes a gas. 21. Define boiling. The process by which a liquid becomes a gas through the production of bubbles. 22. What is the boiling point of water? 100 C 23. Define condensation. The process by which a gas changes into a liquid. Unit 2: Matter & Its Properties, Lesson 3: Particle Movement 24. Define kinetic energy. The energy of motion. 25. How do the particles of matter behave differently in the three states of matter? Solid particles are not free to move around very much. They vibrate back and forth in the same position and are held tightly together by forces of attraction. Liquid particles move much more freely than particles in a solid. They are constantly sliding around and tumbling over each other as they move. Gas particles are far apart and move around at high speeds. Particles might collide with one another, but otherwise they do not interact much. 26. How is the average kinetic energy different in a substance that has a high temperature different than a substance that has a low temperature? A substance that has a high temperature has particles that move very fast and has a high average kinetic energy. The substance feels hot. A substance that has a low temperature has particles that move very slow and has a low average kinetic energy. The substance feels cold.
Unit 2: Matter & Its Properties, Lesson 4: Density 27. Define density. A measure of the amount of mass present in a given volume of a substance 28. What is the formula for density? 29. How are the molecules of an object related to its density? Density describes how closely packed matter is. The most closely packed particles are, the more density. 30. What is the density of CO gas if 0.196 g occupies a volume of 100 ml? m = 0.196 g D = m/v v = 100 ml D = 0.196 g / 100 ml D = 0.00196 g/ml Answer: 0.00196 g/ml 31. A block of wood 3 cm on each side has a mass of 27 g. What is the density of the block? (Hint, don t forget to find the volume of the wood.) l = 3 cm v = l x w x h D = m/v w = 3 cm v = 3 cm x 3 cm x 3cm D = 27 g / 27 cm 3 h = 3 cm v = 27 cm 3 D = 1 g/cm 3 m = 27 g Answer: 1 g/cm 3 32. An irregularly shaped stone was lowered into a graduated cylinder holding a volume of water equal to 2 ml. The height of the water rose to 7 ml. If the mass of the stone was 25 g, what was its density? vi = 2 ml v = vf vi D = m / v vf = 7 ml v = 7ml 2 ml D = 25 g / 5 ml m = 25 g v = 5ml D = 5 g/ml Answer: 5 g/ml 33. Silver has a density of 10.5 grams/cm 3 and gold has a density of 19.3 g/cm 3. Which would have the greater mass, 5cm 3 of silver or 5cm 3 of gold? D (silver) = 10.5 g/cm 3 D (gold) = 19.3 g/cm 3 v (silver) = 5 cm 3 v (gold) = 5 cm 3 m (silver) = D x v m (gold) = D x v m (silver) = 10.5 g/cm 3 x 5 cm 3 m (gold) = 19.3 g/cm 3 x 5 cm 3 m (silver) = 52.5 g m (gold ) = 96. 5 g Answer: gold Unit 3: Atomic Structure & The Periodic Table, Lesson 1: Atoms 34. Define an atom. The smallest unit of matter
35. Define an element. A substance that contains only a single type of an atom 36. Give some examples of elements. Silver, Oxygen, Hydrogen, Helium, Aluminum, Gold 37. Identify the parts of an atom, and define each. Atoms are composed of three types of particles: protons, neutrons, electrons. The protons and neutrons make up the nucleus of the atom, whereas the electrons move around the outside of the atom. The negative electrons stick around the nucleus because they are attracted to the positively charged protons. 38. Where is most of the mass of an atom located? Explain. Electrons are much less massive than protons or neutrons. Therefore, most of the atom s mass is in the nucleus. 39. What does the atomic number tell us? The number of protons in it nucleus 40. What does the atomic mass number tell us? The total number of protons and neutrons in an atom s nucleus Unit 3: Atomic Structure & The Periodic Table, Lesson 2: Elements, Compounds, & Mixtures 41. Explain what an isotope is. An atom of the same element that has a different number of neutrons 42. What are valence electrons? Where can you find them? An electron in an atom that can form a chemical bond with another atom. A valence electron is typically found in the outermost electron shell. Valence electrons can only be found in atoms that do not have a full outermost electron shell. 43. Define an ion. An ion is an atom that has lost or gained one or more electrons. 44. Describe how an atom can be a positive ion or a negative ion. A positive ion has lost an electron. A negative ion has gained an electron. 45. What is the difference between an element, compound, and mixture? Elements are a pure substance, made of only one type of atom. The substances in mixtures remain the same substances (physical change). Compounds are new substances formed by atoms that bond together (chemical change). Mixtures can be separated by physical means. Compounds can be separated only by breaking the bonds between atoms (chemical change). 46. Give an example of a compound. H2O, NaCl 47. What is an example of a mixture? H20 + NaCl
Unit 3: Atomic Structure & The Periodic Table, Lesson 3: The Periodic Table 48. What four items of information are included in each square on the periodic table? (Be sure that you are able to locate elements on the periodic table, if given some of this information.) 49. What does the atomic mass tell us? Atomic mass - The average mass of all the element s isotopes 50. Who published the first periodic table? In what year? Russian chemist Dmitri Mendeleev came up with a system in the 1869 51. How is the modern periodic table organized? Elements with similar properties are found in columns (not rows). The elements are arranged by their atomic number, not by atomic masses. 52. What are rows on the periodic table called? Periods 53. What are columns on the periodic table called? Groups / Families 54. What information does the periodic table tell us? (Hint: there s more than one thing!) Groups: Similar physical and chemical properties; same number of electrons in outer shell Periods: As you move from left to right, additional electrons are added. Unit 3: Atomic Structure & The Periodic Table, Lesson 4: Classification 55. What are the three regions of the periodic table? Metals = left/center Nonmetals (except hydrogen) = right Metalloids = in between 56. List properties of metals. Are solids at room temperature (except Mercury) Can be shaped easily Shiny Good conductors 57. List properties of nonmetals. Many are a gas at room temperature (Bromine is a liquid) Dull surfaces Not easily shaped Generally poor conductors
58. What is a metalloid? An element that has properties of both metals and nonmetals 59. Which two groups on the periodic table are the reactive metals? What are they called? Group 1 (alkali metals) and Group 2 (alkaline earth metals) 60. Which groups on the periodic table are the transition metals? Groups 3-12 61. Where are positive ions typically located on the periodic table? Why? Groups 1-2 because they can easily give away an electron 62. Where are negative ions typically located on the periodic table? Why? Group 17 because they can easily take an electron 63. Using four different physical properties, describe the trends of the periodic table. Density: With each period, the elements are at the right and left edges of the row are least dense. The elements in the middle of the row are the most dense. Hardness: Dense elements tend to be hard. Hardness means a material can t be scratched or dented easily. Conductivity: Elements on the right side of the table (nonmetals) tend to be poor conductors. Elements in the middle and left side of the table (metals) tend to be good conductors. Melting / Boiling Points: Elements on the right side of the table (nonmetals) tend to have lower melting and boiling points. Elements in the middle and left side of the table (metals) tend to have higher melting and boiling points. Unit 4: Chemical Reactions, Lesson 1: Chemical Bonds 64. What is the chemical formula for carbon dioxide? For water? For table salt? CO2 H2O NaCl 65. Define an ion. An ion is an atom that either gains or loses one or more electrons 66. What is an ionic bond? Ions typically form in pairs when one atom transfers one or more electrons to another atom. 67. In general, between what types of elements do ionic bonds form? A metal and a nonmetal 68. What is a molecule? A group of atoms held together by covalent bonds 69. What is a covalent bond? A pair of shared electrons between two atoms 70. In general, between what types of elements do covalent bonds form? Two nonmetals
71. Fill in the number of bonds: a. Group 17 = 1 covalent bond b. Group 16 = 2 covalent bonds c. Group 15 = 3 covalent bonds d. Carbon & Silicon = 4 covalent bonds 72. What is a metallic bond? Metal atoms bond together by sharing their electrons with one another. 73. What two properties of metals are determined by their metallic bonds? Good conductors because of the free movement of electrons Malleable because atoms can slide past one another Unit 4: Chemical Reactions, Lesson 2: Chemical Reactions 74. Define a chemical reaction. Produces new substances by changing the way in which atoms are arranged 75. Circle the reactants. Underline the products: CH4 + O2 à CO2 + H2O 76. Identify signs that a chemical change took place. Production of an odor Production of light Change in temperature Change in color Formation of a gas (bubbles) Formation of a precipitate (a solid) 77. State the Law of Conservation of Energy. Energy cannot be created or destroyed 78. What is the difference between an exothermic reaction and an endothermic reaction? Exothermic reaction - A reaction in which energy is released; Endothermic reaction - A reaction in which energy is absorbed 79. What evidence would indicate an exothermic reaction took place? Temperature increases 80. What evidence would indicate an endothermic reaction took place? Temperature decreases 81. What four factors can change the rate of a chemical reaction? Concentration - A high concentration of reactants means a large number of particles that can collide and react = faster reaction Surface area Increasing the surface area of the material increases the rate of the reaction = faster reaction Temperature - The rate of a reaction can be increased by making the particles move faster (increasing temperature = faster reaction) Catalysts - A catalyst is a substance that increases the rate of a chemical reaction but is not itself consumed in the reaction.
82. State the Law of Conservation of Mass. In a chemical reaction, atoms are neither created nor destroyed 83. According to the Law of Conservation of Mass, the total mass of reactants is equal to the total mass of products. 84. Balance the following chemical equation: N2 + 3H2 à 2NH3 (Be sure to practice others!) Unit 4: Chemical Reactions, Lesson 3: Solutions 85. What is a solution? A mixture of two or more substances that is identical throughout 86. Define an acid. A substance that can donate a hydrogen ion (a proton) to another substance 87. Describe characteristics of an acid. They taste slightly sour when dissolved in water and produce a burning or itchy feeling on the skin. 88. Define a base. A substance that can accept a hydrogen ion from another substance 89. Describe characteristics of a base. They tend to taste bitter, rather than sour, and often feel slippery to the touch. 90. On an atomic level, the difference between acids and bases is that acids donate protons and bases accept protons. 91. When using litmus paper, an acid turns the paper red whereas a base turns the paper blue. 92. Explain how to read a ph scale. The acidity of a solution depends on the concentration of H+ ions in the solution. This concentration is often measured on the ph scale. A ph scale usually has a range from 0-14. Numbers below 7 indicate acidic solutions. A concentrated strong acid has a low ph value. Number above 7 indicate basic solutions. A concentrated strong base has a high ph value. Neutral compounds like pure water have a ph of 7. Unit 4: Chemical Reactions, Lesson 4: Chemistry of Living Things 93. Define biochemistry. The study of the substances and processes occurring in living organisms 94. Identify the six most common elements in living things. Carbon Hydrogen Oxygen Nitrogen Phosphorus Sulfur
95. What are the two most important compounds for living things? Water and salt 96. What is the most important element for living things? Carbon 97. Explain the difference between an organic compound and an inorganic compound. A compound based on carbon. All living things (organisms) are organic because they contain carbon. Any compound that do not contain carbon. But it also includes some carbon-containing compounds that are not found in living things. 98. What are the four major groups of organic molecules in living things (biomolecules)? Provide functions for each. Carbohydrates include sugars and starches. They are found in goods, like pasta and bread. Contains: carbon, hydrogen, and oxygen; Functions: chemical energy for cells; structural materials of plants Lipids are fats or oils. Contains: carbon, hydrogen, and oxygen. Animals store chemical energy in fat; plants store chemical energy in oils. Some lipids are important parts of cell structure. Proteins are necessary for many functions in the body, including the formation of muscle tissue. Contains: carbon, hydrogen, oxygen, nitrogen, sulfur, and others. There are at least 100,000 proteins in your body, each with a different structure that gives it a specific function: o Structural materials o Control chemical reactions o Transport substances within cells o Part of the immune system and protect you from infections Some proteins that curl up into a shape of a ball are enzymes. They are necessary for many chemical reactions in your body. Without enzymes, these reactions would occur too slowly to keep you alive. Nucleic acids are the molecules that carry the genetic code for all living things. Examples: DNA and RNA. Contains: carbon, hydrogen, oxygen, nitrogen, and phosphorus. Each of the cells in your body contains a complete set of nucleic acids. This means that each cell has all the instructions necessary for making any protein in your body.