Unit 3: Atomic Structure Text Questions from Corwin. Ch How did the views of Democritus and Aristotle disagree with regard to matter?

Transcription

1 Unit 3: Atomic Structure Name: KEY Text Questions from Corwin Ch How did the views of Democritus and Aristotle disagree with regard to matter? D said matter was discontinuous (i.e., grainy ); A said matter was continuous What did Dalton offer for his ideas about the atom, which set him apart from the Greek thinkers? he presented convincing experimental evidence 3. Besides Boyle s experiments, what two other principles did Dalton employ in his model of the atom? the law of conservation of mass and the law of definite composition 4. Of Dalton s five statements about the atom, which two do we NOT believe in today? State those two. D s claims that atoms are indivisible and that all atoms of an element are identical Thomson s model of the atom was of a positively charged atom containing negatively charged electrons 6. What were two popular names given to Thomson s model? the plum-pudding model or the raisin-pudding model What did Rutherford conclude about WHY most of the alpha particles passed through the foil? the atom is largely empty space with electrons moving about 8. What two things did Rutherford reason about the nucleus? compared to the atom, the nucleus is tiny and has a very high density 9. Describe the model of the atom that Rutherford proposed in negative e- were distributed about a positively charged nucleus 10. The size of an atom compared to the size of its nucleus is similar to a kilometer compared to a centimeter 11. About how many years passed between Rutherford s work and the discovery of the neutron? What is the difference between the atomic number and the mass number? atomic # = # of p+; mass number = # of p+ plus n Write out a generic atomic notation, and identify all of the terms. Sy = element symbol; A = mass number; Z = atomic number 14. What are isotopes? atoms of the same element that have diff. #s of neutrons

2 What is an atomic mass unit equal to? 1/12 th the mass of the carbon-12 atom 16. Define atomic mass. the weighted average of all naturally occurring isotopes 17. What two things are needed to calculate an element s atomic mass? the mass of each isotope and their percent abundances 18. The atomic mass of carbon is _12.01_ amu, but no carbon atom weighs this amount. A carbon atom weighs either _12.000_ amu or _13.003_ amu. The atomic mass of carbon represents the mass of a _hypothetical_ average carbon atom. 19. From the periodic table, how can you identify the elements that are radioactive? there is a whole number in parentheses below the element symbol Wavelength refers to the distance light travels to complete one cycle 21. Frequency refers to the number of wave cycles completed in each second 22. What is the relationship between frequency and wavelength? as one increases/decreases, the other decreases/increases (i.e., an inverse relationship) 23. What is the relationship between frequency and energy? they are directly related (as one goes up/down, the other goes up/down) 24. What is the range of wavelengths that constitutes the visible spectrum? nm 25. How do the wavelengths of ultraviolet radiation and infrared radiation compare to visible wavelengths? UV has shorter than 400 nm wavelengths; IR has longer than 700 nm wavelengths 26. The continuous spectrum is also called the radiant energy spectrum 27. List at least four types of radiant energy that make up the continuous spectrum. gamma rays, X rays, microwaves, visible light, UV, IR, cosmic rays, radio waves What did Max Planck propose in 1900? that the energy radiated by a heated object was not continuous, but emitted in small bundles 29. Although radiant energy has a _wave_ nature, it also has a _particle_ nature. 30. What is a photon? an individual unit of light energy 31. With reference to Figure 5.10 The quantum concept of energy is analogous to the ball losing potential energy as it travels down the _stairs_ Bohr proposed that electrons orbit the nucleus just as planets orbit the Sun

3 33. What two things did Bohr suggest about electron orbits? that they were at a fixed distance from the nucleus and had a definite energy 34. According to Bohr, an energy level is a fixed-energy orbit 35. According to Bohr, electrons could be found only in _specific_ energy levels and _nowhere else_. 36. The paper that Bohr received: What did it show? that excited hydrogen gas emits separate emission lines of light, not a continuous band of color 37. An _emission_ spectrum is emitted when a gas is excited by an electrical _voltage_. The gas, which is sealed in a _discharge_ tube, emits light that can be separated into a _series_ of narrow _lines_ when passed through a _prism_. 38. Bohr realized that the emission spectrum of hydrogen was experimental _evidence_ to support his model of the atom. 39. In a hydrogen discharge tube, excited H atoms have electrons in a _high_ energy orbit. Because this is an _unstable_ state, the electron _drops_ to a lower level. In doing so, the electron _loses_ a definite amount of energy; this corresponds to a _photon_ of light energy. The energy of the _photon_ is _equal_ to the energy _lost_ by the electron as it _drops_ to a lower energy level. 40. How many photons are emitted when a single electron drops to a lower energy level? one 41. What did the further study of emission spectra reveal? that each element produced a unique set of spectral lines 42. This atomic fingerprint indicated that the energy levels must be unique for atoms of each element 43. In years after it was discovered to exist in the Sun where ELSE was helium found? in uranium ore Could Bohr explain the spectra of other elements, besides hydrogen? no 45. Within a main energy level, Bohr suggested the idea of energy sublevels 46. Write the designations AND what the designations stand for for the four types of energy sublevels. s (sharp), p (principal), d (diffuse), f (fine) 47. The type of sublevel determines what? the max # of e- in each energy sublevel 48. How many electrons can the following sublevels hold? s p d f Compared to those closer to the nucleus, electrons farther from the nucleus occupy higher energy levels

4 List the first twelve sublevels, in order of increasing energy. 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s 51. What is an electron configuration? a shorthand statement describing the location of electrons by sublevel 52. First, the _sublevel_ is written, followed by _superscript_ indicating the number of electrons 53. For a given element, WHAT corresponds to the number of electrons in a neutral atom? the atomic number 54. For neutral atoms, the _sum_ of the _superscripts_ equals the _atomic number_ of the element Why was it desirable that a more powerful atomic theory emerge in the 1920s? the behavior of electrons could not be fully explained by Bohr s model 56. What did Heisenberg state, in his uncertainty principal? you can t simultaneously & precisely measure both location & momentum/energy of a small particle 57. The more accurately the position of an electron is known the less precisely its energy can be determined 58. Following Bohr s model, the quantum mechanical model retained WHAT, but incorporated what ELSE? retained quantized energy levels, but incorporated uncertainty 59. How is the energy of an electron described, in the quantum mechanical model? in terms of the probability of it being within a certain spatial volume around the nucleus 60. What is an orbital? a region of high probability for finding an electron of a given energy 61. The shape of an s orbital is that of a _sphere_. A p orbital is shaped like a _dumbbell_. 62. Although all s orbitals are _spherical_, they are NOT all the same _size_. Similarly, all of the _dumbbell_-shaped p orbitals are NOT the same _size_.

5 Unit 3: Atomic Structure Name: Text Questions from Corwin Ch How did the views of Democritus and Aristotle disagree with regard to matter? What did Dalton offer for his ideas about the atom, which set him apart from the Greek thinkers? 3. Besides Boyle s experiments, what two other principles did Dalton employ in his model of the atom? 4. Of Dalton s five statements about the atom, which two do we NOT believe in today? State those two Thomson s model of the atom was of a positively charged atom containing 6. What were two popular names given to Thomson s model? What did Rutherford conclude about WHY most of the alpha particles passed through the foil? 8. What two things did Rutherford reason about the nucleus? 9. Describe the model of the atom that Rutherford proposed in The size of an atom compared to the size of its nucleus is similar to 11. About how many years passed between Rutherford s work and the discovery of the neutron? What is the difference between the atomic number and the mass number? 13. Write out a generic atomic notation, and identify all of the terms. 14. What are isotopes?

6 What is an atomic mass unit equal to? 16. Define atomic mass. 17. What two things are needed to calculate an element s atomic mass? 18. The atomic mass of carbon is amu, but no carbon atom weighs this amount. A carbon atom weighs either amu or amu. The atomic mass of carbon represents the mass of a average carbon atom. 19. From the periodic table, how can you identify the elements that are radioactive? Wavelength refers to 21. Frequency refers to 22. What is the relationship between frequency and wavelength? 23. What is the relationship between frequency and energy? 24. What is the range of wavelengths that constitutes the visible spectrum? 25. How do the wavelengths of ultraviolet radiation and infrared radiation compare to visible wavelengths? 26. The continuous spectrum is also called the 27. List at least four types of radiant energy that make up the continuous spectrum What did Max Planck propose in 1900? 29. Although radiant energy has a nature, it also has a nature. 30. What is a photon? 31. With reference to Figure 5.10 The quantum concept of energy is analogous to the ball losing potential energy as it travels down the Bohr proposed that electrons orbit the nucleus just as

7 33. What two things did Bohr suggest about electron orbits? 34. According to Bohr, an energy level is 35. According to Bohr, electrons could be found only in energy levels and. 36. The paper that Bohr received: What did it show? 37. An spectrum is emitted when a gas is excited by an electrical. The gas, which is sealed in a tube, emits light that can be separated into a of narrow when passed through a. 38. Bohr realized that the emission spectrum of hydrogen was experimental to support his model of the atom. 39. In a hydrogen discharge tube, excited H atoms have electrons in a energy orbit. Because this is an state, the electron to a lower level. In doing so, the electron a definite amount of energy; this corresponds to a of light energy. The energy of the is to the energy by the electron as it to a lower energy level. 40. How many photons are emitted when a single electron drops to a lower energy level? 41. What did the further study of emission spectra reveal? 42. This atomic fingerprint indicated that 43. In years after it was discovered to exist in the Sun where ELSE was helium found? Could Bohr explain the spectra of other elements, besides hydrogen? 45. Within a main energy level, Bohr suggested the idea of 46. Write the designations AND what the designations stand for for the four types of energy sublevels. 47. The type of sublevel determines what? 48. How many electrons can the following sublevels hold? s p d f 49. Compared to those closer to the nucleus, electrons farther from the nucleus occupy

8 List the first twelve sublevels, in order of increasing energy. 51. What is an electron configuration? 52. First, the is written, followed by indicating 53. For a given element, WHAT corresponds to the number of electrons in a neutral atom? 54. For neutral atoms, the of the equals the of the element Why was it desirable that a more powerful atomic theory emerge in the 1920s? 56. What did Heisenberg state, in his uncertainty principal? 57. The more accurately the position of an electron is known 58. Following Bohr s model, the quantum mechanical model retained WHAT, but incorporated what ELSE? 59. How is the energy of an electron described, in the quantum mechanical model? 60. What is an orbital? 61. The shape of an s orbital is that of a. A p orbital is shaped like a. 62. Although all s orbitals are, they are NOT all the same. Similarly, all of the -shaped p orbitals are NOT the same.