Name Date Period Concepts to know for the Unit 3 test: Chemistry: Unit 3 - Atoms Test Review KEY 1. Summarize the major experimental evidence that led to the development of various atomic models, both historical and current. 2. Evaluate the limitations of using models to describe atoms. a. Aristotle: a. WRONG, four elements earth, air, water, fire b. Democritus: a. Everything is made of small indivisible particles, coined atomos c. John Dalton: a. All matter is made of atoms b. Compounds are combinations of 2+ kinds of atoms, atoms are rearranged in chemical reactions c. Atoms cannot be divided (FALSE because protons, neutrons, electrons exist) d. All atoms of a given element are identical (FALSE because isotopes with different # of neutrons exist), e. Atoms cannot be destroyed (FALSE because nuclear reactions change identity of atoms) f. Billiard ball model of the atom (INCORRECT because no protons, neutrons, or electrons) d. JJ Thompson: a. Cathode ray tube experiment b. Discovered electron c. Plum pudding model (INCORRECT because no nucleus) e. Robert Millikan: a. Oil drop experiment b. Discovered charge-to-mass ratio of electron f. Ernest Rutherford: a. Gold foil experiment b. Discovered nucleus c. Planetary model (INCORRECT because no energy levels) g. Niels Bohr: a. Discovered energy levels for electrons b. Bohr model 3. Discriminate between the relative size, charge, and position of protons, neutrons, and electrons in the atom. a. Discriminate between the relative size, charge, and position of protons, neutrons, and electrons in the atom. a. Proton: positive charge, 1 amu, found in nucleus b. Neutron: no charge, 1 amu, found in nucleus c. Electron: negative charge, 1/2000 amu, orbits nucleus
4. Generalize the relationship of proton number to the element s identity. a. # protons = atomic number = identifies the element 5. Relate the mass and number of atoms to the gram-sized quantities of matter in a mole. a. 1 mole = 6.02 x 10 23 particles (particles = atoms, molecules, doughnuts, etc.) b. Atomic mass and molar mass are the same numbers, just different units c. Determine atomic/molar mass from the periodic table d. For a compound, add the masses of all the parts a. H2O = 2H + O = 2(1.01) + 15.99 = 18.02 e. Atomic mass: units of amu, used for measuring the mass of a single particle (atom, molecule, etc.) f. Molar mass: units of g/mol, used for measuring the mass of a mole of particles g. To convert moles mass (g): multiply by molar mass (g/mol) h. To convert mass (g) moles: divide by molar mass (g/mol) 6. Use the periodic table to correlate the number of protons, neutrons, and electrons in an atom. a. Atomic number: of protons b. Mass number: of protons + number of neutrons c. of electrons: Same as # of protons in neutral atom a. # Electrons > # Protons NEGATIVE charge b. # Protons > # Electrons POSITIVE charge 7. Compare the number of protons and neutrons in isotopes of the same element. a. Isotopes: atoms with same number of protons and different number of neutrons b. Hyphen notation: Name-Mass # (E.g.: Helium-4) c. Nuclear symbol: 8. Recognize that radioactive particles and wavelike radiations are products of the decay of an unstable nucleus. a. Radioactive atoms decay through fission b. Nuclear becomes unstable when it becomes too big 9. Interpret graphical data relating half-life and age of a radioactive substance. In the graph to the left, the half-life (time it takes to lose 50% of the sample) is 7 seconds. In 21 seconds, three half-lives will have passed and only 1/8 of the original sample will remain.
10. Compare the mass, energy, and penetrating power of alpha, beta, and gamma radiation. a. Alpha: Helium-4 nucleus, low penetrating power b. Beta: Electron, intermediate penetrating power c. Gamma: High-energy radiation, high penetrating power 11. Evaluate and report the effects of nuclear radiation on humans or other organisms. a. Nuclear radiation can cause sickness, burns, death, etc. Available on the Test: Periodic Table Calculator 1. What is the atomic mass of each of the following elements or compounds? a. Nickel 58.693 amu b. H 2SO 4 (sulfuric acid) 2(1.01) + 32.07 + 4(15.99) = 98.05 amu 2. What is the molar mass of each of the following elements or compounds? a. Bromine 79.907 g/mol b. NH 3 (ammonia) 14.01 + 3(1.01) = 17.04 g/mol 3. How many moles are in 15.05 g cobalt, Co? 15.05 g Co 1 mol Co = 0.255 moles 58.933 g 4. How many grams are in 4.5 mol ozone (O 3)? Hint: Calculate the molar mass of O 3. Molar mass ozone = 3(15.99) = 47.997 g/mol 4.5 mol O 3 47.997 g = 215.99 g 1 mol 5. Os-182 has a half-life of 21.5 hours. How many grams of a 10.0 gram sample would have decayed after exactly three half-lives? 10.0 g / 2 = 5.0 g / 2 = 2.5 g / 2 = 1.25 g 1 st 2 nd 3 rd Half-lives
6. Look at the following diagram and complete the information about this atom: Atomic number: 2 of Protons: 2 of Neutrons: 1 of electrons: 2 Mass : 3 Element name: Helium Hyphen notation: Helium-3 Nuclear Symbol 2 3 He Proton Neutron 7. Complete the following table Element Name Nitrogen 7 Atomic of Protons 7 of Neutrons of Electrons Mass Hyphen Notation Nuclear Symbol 8 7 15 Nitrogen-15 7 15 N Calcium 20 20 22 18 42 Calcium-42 20 42 Ca 2+ Bromine 35 35 45 35 80 Bromine-80 80 35Br - Uranium 92 92 143 92 235 Uranium-235 92 235 U 8. Sketch each model of the atom. Describe the discovery that led to each model. a. Billiard ball model i. John Dalton s atomic theory ii. Everything is made of atoms iii. Atoms aren t divisible b. Plum pudding model i. Thomson ii. Cathode ray tube experiment iii. Discovery of electron c. Planetary model i. Rutherford ii. Gold foil experiment iii. Discovery of nucleus d. Bohr model i. Energy levels ii. Hydrgogen line spectrum my bad, we ll do this experiment in unit 4!
Practice Problems from the game: 1. What one number identifies an element? a. Protons / Atomic number 2. What is the relationship between electrons and protons in a neutral atom? a. Same number of each 3. Where are electrons located in an atom? a. Orbiting outside 4. How many electrons can be held in the first energy level? a. 2 5. How many electrons can be held in the second energy level? a. 8 6. Where are protons located in an atom? a. Nucleus, center 7. Where are neutrons located in an atom? a. Nucleus, center 8. Write the atomic number for Chlorine a. 17 9. Write the atomic number for Gold a. 79 10. Write the atomic number for Lead a. 82 11. Write the atomic number for Uranium a. 92 12. Write the atomic number for Calcium a. 20 13. Write the atomic number for Xenon a. 54 14. Define isotopes a. Atoms that have the same number of protons but different numbers of neutrons. 15. Define ions. a. Charged particles due to gain or loss of electrons. 16. Define proton. a. Positively charged particle found in the nucleus. 17. Define neutron. a. Neutral particle found in the nucleus, same size as a proton. 18. Define electron. a. Negatively charged particle found outside of the nucleus. 1/2000 size of proton. 19. Define fission. a. Atom splits apart. 20. Define fusion. a. Atoms fuse together. 21. Define half-life. a. Time it take half a radioactive substance to decay. 22. Define alpha decay. a. Helium-4 nucleus 23. Define beta decay. a. Electron 24. Define gamma decay. a. Energy 25. What material can block alpha decay? a. Paper 26. What material can block beta decay? a. Aluminum 27. What material can block gamma radiation?
a. Lead, concrete 28. Describe the plum pudding model of the atom. a. Negative plums suspended in positive matrix. 29. Describe the planetary model of the atom. a. Nucleus in center, electrons orbit outside. 30. Who conducted the gold foil experiment? a. Rutherford 31. What was discovered in the gold foil experiment? a. Nucleus 32. Who conducted the Cathode Ray Tube experiment? a. JJ Thomson 33. What was discovered in the cathode ray tube experiment? a. Electrons 34. What was discovered in the oil drop experiment? a. Mass-charge ratio of electrons. 35. Who conducted the oil drop experiment? a. Millikan 36. Who erroneously believed in the four elements Earth, Air, Fire, and Water? a. Aristotle 37. How is John Dalton important in modern atomic theory? a. 5 principles about reactions and identity of atoms, reintroduced concept of atoms 38. What is the mass number of Carbon-14 a. 14 39. What is the mass number of Helium-3? a. 3 13 40. What is the mass number of C 6 a. 13 41. What is the mass number of Calcium-42? a. 42 42. What is the atomic mass of Iron a. 55.847 43. What is the atomic mass of Calcium a. 40.078 44. What is the atomic mass of Neon a. 20.180 45. What is the atomic mass of Cobalt a. 58.933 46. What is the atomic mass of methane, CH 4 a. 16 47. What is the molar mass of Copper a. 63.546 48. What is the molar mass of Magnesium a. 24.305 49. What is the molar mass of Carbon Dioxide CO 2 a. 44 50. What is the molar mass of Ammonia, NH 3 a. 17.04 51. What is the molar mass of Copper chloride, CuCl 2 a. 134.452 52. What is the molar mass of propane C 3H 8? a. 44 53. How is atomic mass of an element calculated? a. From the periodic table 54. How is the molar mass of a compound such as H 2O or NaCl calculated? a. Sum of individual atomic masses
55. How many particles are in one mole of a substance? a. 6.02 x 10 23 56. Explain how you convert from GRAMS to MOLES a. Divide by the molar mass 57. Explain how you convert from MOLES to GRAMS a. Multiply by the molar mass 58. What form of radioactive decay has the most penetrating power? a. Gamma 59. Least, above? a. Alpha 60. What is the formula for density? a. Mass / volume 61. What is the formula for percent error? a. Actual-experimental / Actual