24-25 Chemistry Midterm Review Answers PDF

1. What are the steps to the scientific method? Define them Observation, and ask a question do research,construct hypothesis,test your experiment, results. Conclusion, communicate. 2. do we do in each of the steps? Observation and ask a question must be testable something you must do experiment to f...

1. What are the steps to the scientific method? Define them Observation, and ask a question do research,construct hypothesis,test your experiment, results. Conclusion, communicate. 2. do we do in each of the steps? Observation and ask a question must be testable something you must do experiment to figure out, do research you want to know as much as humanly possible,construct hypothesis an educated guess based on your background research about what the answer to your question,test your experiment identify your variables, results is where you report what happened in the experiment. Conclusion is whether your results align with hypothesis or not. Communicate is when you tell others. 3. What is the difference between quantitative and qualitative data? Quantitative data is the one that can be measured(numbers) and qualitative is descriptive and cannot be measured with numbers. 4. Difference between independent and dependent variables and prove at least 3 examples. An independent variable is changed in an experiment. The dependent variable is what you measure in the experiment. Examples: A.​ Independent variable: Amount of sunlight; Dependent variable: Plant growth. B.​ Independent variable: Exercise duration; Dependent variable: Heart rate. C.​ Independent variable: Temperature; Dependent variable: Ice cream sales. 5. For a graph, what variable is the x axis and which is the y axis? Independent variable is x axis and dependent variable is usually y 6. Relationship between your results and conclusion. Results are written in conclusion when you compare with your hypothesis and say whether you predicted or not. 7. What are some ways we can communicate our results? By written, presentation , or other ways. 8. 0.005g/mL 9. 25000g 10. 1200mL 11. What is matter broken down into (the whole diagram) 12. What is a pure substance? Is a substance that has constant composition and properties 13. What is an element? Is a pure substance that cannot be broken down by ordinary means. 14. What is the difference between a mixture and a pure substance? mixture is matter that is made up of only one type of atom and pure substance is matter that is made up of more than one type of atom 15. What is the chemical symbol, atomic number, # of protons and electrons, and atomic mass of all the following: Iron, Argon, Americium, Francium, Bromine, Radium, Nobelium, Iodine, Potassium, Gold, Silver, Caesium. Radium atomic number: 88 chemical symbol: Ra atomic mass: 226 u protons: 88 neutrons: 138 Nobelium atomic number: 102 chemical symbol: No atomic mass: 259u protons: 102 neutrons:157 Iodine atomic number: 53 chemical symbol: I atomic mass: 126.90447 u protons: 53 neutrons: 74 Potassium atomic number: 19 Chemical symbol: K atomic mass: 39.0983 u protons: 19 neutrons: 20 Gold atomic number: 79 chemical symbol: Au atomic mass: 196.967u protons: 79 neutrons: 118 Silver atomic number:47 chemical symbol: Ag atomic mass:107.8682 u protons: 47 neutrons: 61 Caesium atomic number: 55 Chemical symbol: Cs atomic mass:132.90545 u protons: 55 neutrons:78 16. Why are some chemical symbols structured differently? it is determined by their atomic structure 17. What is a compound? (Give examples) consists of two or more elements chemically bonded in a fixed ratio ex. salt,water,sand, hyaluronic acid 18. What is required for breaking down a compound? a chemical change is required 19. What is electrolysis used for? to purify metals or extract them from a solution or break down substances into their individual components 20. Can compounds be more stable than individual elements? chemical bonds are formed when electrons in different atoms interact with each other to make an arrangement that is more stable than when the atoms are apart 21. What is an atom? composed of protons, which have a positive charge, and neutrons, which have no charge is a particle in element is smallest unit of an element 22. What is a molecule? A molecule is the combination of two or more atoms. 23. What is the difference between a molecule and a compound? A molecule is a group of two or more atoms held together by chemical bonds while a compound is a substance formed by two or more elements which are chemically united in a set way. 24. What is a mixture? A mixture is a substance that contains two or more pure substances that are NOT chemically combined. 25. What are the types of mixtures and the difference between them? There are two types of mixtures which are heterogeneous and homogeneous mixtures. Heterogeneous mixtures are mixtures that do not blend smoothly throughout and in which the individual substances remain distinct. Homogeneous mixtures are mixtures that have a constant composition throughout and are always just one phase. 26. Give 3 examples of heterogeneous mixtures and homogeneous mixtures. Heterogeneous - pizza, soup, and sand in water. Homogeneous - air, sugar, and water. 27. What is the difference between a solute and solvent? Solute is the substance that is being dissolved, Solvent is the dissolving medium. 28. Identify the solute and solvent in the following mixtures: chocolate milk, sugar water, iced tea, lemonade, jello, coffee, salted boiling water. Chocolate milk - solute: coca powder, solvent: milk, Sugar water - solute: sugar, solvent: water, iced tea - solute: tea, solvent: water, lemonade - solute: lemon juice and sugar, solvent: water, jello - solute: gelatin, solvent: water, coffee - solute: coffee powder, solvent: water, salted boiling water - solute: salt, solvent: water 29. What are the different states of matter, how are the particles arranged, and list them in lowest to highest energy output? There are three main states of matter: solid, liquid and gas. This physically changes the substance, but it does not change any chemical properties. Solid: Has the least kinetic energy. Molecules move slower than those of a liquid or gas. Liquid: Has more kinetic energy than a solid but less than a gas. 30. What is a physical property? A physical property is a characteristic of matter than can be observed or measured without changing the sample’s composition. 31. List 3 examples of physical properties. Volume, mass, and size 32. What is a chemical property? A chemical property is the ability or inability of a substance to combine with or change into more substances. 33. List 3 examples of chemical properties? Ability to burn, Ability to tarnish, Decompose 34. What is the difference between extensive and intensive properties? Extensive Properties are dependent on the amount of substance present. Intensive Properties are independent of the amount of density of a substance present. 35. What processes can cause a physical change? Grinding, cutting, crushing, bending 36. How do chemical changes occur? Energy can be either released or absorbed in the form of light or heat 37. What is the difference between exothermic and endothermic? Exothermic is a chemical reaction that releases energy in the form of heat. Endothermic is a chemical change that absorbs energy In the form of heat. 38. What is water made up of? 3 atoms: 1 oxygen and 2 hydrogen that are connected by covalent bonds 39. What gives water its special properties? The polarity of water 40. What is cohesion? The tendency of water molecules to stick together because of hydrogen bonding 41. What is adhesion? Water molecules sticking to something other than water due to the attraction of charges 42. What is capillary action? The tendency of water to move along the surface of a substance due to adhesion. 43. What is surface tension? A special form of cohesion that causes the surface of water to resist rupture (the reason certain insects can walk on water and certain lizards can run on water). 44. Why is water a universal solvent? Because of the partial charge within the water molecule. 45. What makes water have polarity? Water consists of a positive hydrogen side and negative oxygen side. 46. What is the difference between hydrophobic and hydrophilic? Hydrophobic = water fearing, while Hydrophilic = water loving. 47. What did Aristotle believe matter was made of? Earth, fire, and water. 48. What does the law of conservation of mass state? Mass is conserved in any process. 49. What is an atom? The smallest particle of matter that retains the properties of the element. 50. What is an electron? Particles with a negative charge. 51. Who identified the electron? Robert Millikan. 52. What charge does an electron have? Negative. 53. What is an isotope? distinct nuclear species of the same chemical element 54. What is the atomic mass? mass of an atom 55. What is radioactivity? the emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei 56. What is radiation? the rays and particles emitted by the radioactive material 57. Who created the “Table of Simple Substances”? Antoine Lavoisier 58. Who came up with the law of octaves? John Newlands 59. What is the law of octaves? he noticed that the properties repeated every 8th element 60. What did Mendeleev’s periodic table show that was ahead of his time? The two could be combined in a single framework, elements that were undiscovered 61. What were Henry Moseley contributions to the classification of elements? Arranged the elects in the periodic table according to atomic numbers 62. How many periods are on the periodic table? 7 periods 63. How many groups are on the periodic table? 18 64. Which groups of elements on the periodic table are referred to as representative elements? Groups 1&2 13-18 65. What are groups 3-12 referred to as on the periodic table? Transition elements 66. What are metals? Shiny, smooth, clean, solid at room temp, good conductors 67. What are alkali metals? Group 1 elements (except hydrogen), reactive and exist as compounds with other elements 68. What are transition elements divided into? Inner transition metals 69. What are the two sets of inner transition metals? Lanthanide and Actinide 70. What are the elements in group 17 known as? Halogens 71. What determines the chemical properties of elements? Electron configuration 72. List the 4 orbitals, how many electrons they can hold, their energy levels, and location on the periodic table. S-P-D-F; s: 2 p:6 d:10 f:14. 73. How many valence electrons do group 2 elements have? 2 74. What is Aufbau’s principle? Electrons fill lower energy atomic orbitals before filling higher energy orbitals 75. What is an electron cloud? Spherical surface within which there is a 90% chance to find an electron 76. What is atomic size? How close an atom lies to a neighboring atom 77. What is an ion? An atom or a bonded group of atoms that have either a positive or negative charge 78. What is ionization energy? The energy required to remove an electron from a gaseous atom 79. How does the charge of an atom change if it gains or loses an electron? If an atom gains electrons, its overall charge becomes negative. If an atom loses electrons, its overall charge becomes positive. 80. What is Planck’s constant? 6.63*10^-34 Js 81. Copper has 2 isotopes: Cu-65 (abundance = 30.8%, mass = 64.92) and Cu-63 (abundance = 69.2%, mass = 62.93). Calculate the atomic mass of copper. 63.55 amu 82. When electrons move between energy levels, what is produced? 83. What is the electron configuration of the following: Boron, Fluorine, Sodium, Magnesium, Sulfur, Aluminum, Chlorine, Calcium, Titanium, Nickel, Silver, Xenon, Tin, Iodine Boron- 1s2 2s2 2p1 Fluorine- 1s2 2s2 2p5 Sodium- 1s2 2s2 2p6 3s1 Magnesium- 1s2 2s2 2p6 3s2 Sulfur- 1s2 2s2 2p6 3s2 3p4 Aluminum- 1s2 2s2 2p6 3s1 3p1 Chlorine- 1s2 2s2 2p6 3s2 3p5 Calcium- 1s2 2s2 2p6 3s2 3p6 4s2 Titanium- 1s2 2s2 2p6 3s2 3p6 4s2 3d2. Nickel- 1s2 2s2 2p6 3s2 3p6 4s2 3d8 Silver- 1s2 2s2p6 3s2p6d10 4s2p6d10 5s1 Xenon- 1s2 2s2p6 3s2p6d10 4s2p6d10 5s2p6 Tin- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p2 Iodine- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p5