Atomic Theory and Models of the Atom. 1. An atom has 65 neutrons and a mass of 122 u. Write the proper nuclide symbol.

Transcription

1 PSI AP CHEMISTRY Summer Assignment Review Unit Free Response Classwork: Atomic Theory and Models of the Atom 1. An atom has 65 neutrons and a mass of 122 u. Write the proper nuclide symbol. 2. Atom A has 11 neutrons and Atom B also has 11 neutrons. Are these atoms isotopes? Explain. 3. Which component of Dalton s atomic theory reflects his understanding of the law of conservation of mass for chemical processes? Why? 4. The atomic masses of elements are generally not whole numbers. Explain why. 5. Gallium has two stable isotopes: Ga - 69 (68.92 u) and Ga-71 (70.92 u). Using the average atomic mass of gallium, what is the % abundance of the heavier of the two isotopes? 6. Naturally occurring chlorine is 75.78% Cl - 35 ( u) and 24.22% Cl - 37 ( u). Calculate the average atomic mass. 7. What conclusions were made from Rutherford s Gold Foil Experiment? How did this experiment change the atomic model? 8. Explain why the Bohr model was insufficient and how the quantum model explained this deficiency. How is the electron viewed differently in each model? 9. Consider the equations relating wavelength, frequency and energy of electromagnetic radiation. How is the energy of a photon related to its frequency and wavelength? 10. Calculate the frequency of an X ray that has a wavelength of 8.21 nm. 11. What is the frequency of a photon that has an energy of J 12. Provide a brief explanation for what each of the four quantum numbers describes.

2 Homework: 1. Radioactive americium is used in household smoke detectors and in bone mineral analysis. a) Give the number of electrons, protons, and neutrons in an atom of americium b) Write the proper nuclide symbol. 2. What characteristics do atoms of carbon-12, carbon-13, and carbon-14 have in common? IN what ways are they different? 3. Identify the isotope that has atoms with a) 117 neutrons, 77 protons, and 77 electrons b) 30 neutrons, 28 protons, and 28 electrons 4. How did the discovery of isotopes conflict with Dalton s atomic theory? 5. The average mass of any large number of atoms of a given element is always the same for a given element. Explain. 6.. Naturally occurring boron is 19.9% B - 10 (mass = u) and 80.1% B - 11 (mass = u). Calculate the average atomic mass. 7. Uranium has an atomic mass equal to It consists of two isotopes: uranium with an isotopic mass of u and uranium-238 with an isotopic mass of u. Calculate the % abundance of the uranium-235 isotope. 8. How did Rutherford interpret the deflection of α-particles in his gold foil experiment? Did these findings support or disprove the plum pudding model of the atom? Explain. 9. How does Bohr's model of the atom explain the existence of line spectra? How are spectral lines produced? 10. What is the energy of a photon that has a wavelength of 8.33 x 10-6 m? 11. What is the wavelength of a photon that has an energy of J 12. How does the quantum model describe the location of an electron? Periodic Table

3 Classwork: 1. An element is found to gain three electrons when it forms an ion. a) What group number would this element be found in? b) Is there enough information provided to determine what period it is in? 2. Look at the average atomic mass of Ar and K. a) Explain why early scientists might have been tempted to have K follow Cl on the periodic table. b) Propose two reasons as to why they placed Ar after Cl instead of K. 3. Identify the following elements: a) An alkali metal in the 5th period. b) A transition metal c) An atom in the 3rd period that forms a stable ion with a -1 charge. 4. Explain why atoms tend to gain or lose electrons relative to the number of valence electrons. 5. What ions are the following elements likely to form? a) Nitrogen b) Calcium c) Sulfur 6. Explain why the noble gases are inert (unreactive). 7. Why are the charges of transition metals (d-block) difficult to predict? 8. Write the formulas for the following binary ionic compounds. a) magnesium oxide b) manganese(ii) chloride c) calcium phosphide d) copper(i) sulfide 9. Write the formulas for the following polyatomic ionic compounds. a) potassium sulfate b) aluminum phosphate c) iron(iii) carbonate d) aluminum hydroxide 10. Aluminum reacts with a certain nonmetallic element to form a compound with the general formula Al 2X 3. Element X must be from which group on the periodic table? Homework:

4 1. What accounts for similarities of chemical properties for elements in the same group(family)? 2. Provide the group names for the elements in Group 1, 2, 17 and 18. Provide and example of an element in each of the above groups. 3. Identify the following elements: a) A halogen in the 3rd period. b) A metalloid c) An atom in the 4th period that forms a stable ion with a +1 charge. 4. Locate the following elements on the periodic table and indicate which orbital type is occupied by its valence electrons a) Lithium b) Silicon c) Copper 5. What ions are the following elements likely to form? a) Oxygen b) Sodium c) Bromine 6. A main group element in Period 4 forms the molecular compound H 2E and the ionic compound Na 2E. a) To which group does the element belong? b) Write the name and symbol of the element. 7. Write the formulas for the following binary ionic compounds. a) sodium sulfide b) cobalt(ii) chloride c) lithium nitride d) Tin(IV) oxide 8. Write the formulas for the following polyatomic ionic compounds. a) barium nitrate b) calcium phosphite c) iron(ii) chromate d) potassium permanganate 9. How many total ions (cations and anions) are present in the following ionic compounds? a) sodium acetate b) aluminum nitrate

5 c) Copper(II) chloride 10. The most common charge associated with silver in its compounds is +1. Indicate the formulas you would expect for the ionic compounds formed between silver and the following elements. a) iodine b) sulfur c) phosphorous Classwork: Mole Concept 1. Answer the following questions for the compound aluminum sulfate. a) What is the molar mass of this compound? b) What is the mass of a 1.5 mole sample? c) How many oxygen atoms are present in the 1.5 mol sample 2. What mass of rhodium contains as many atoms as there are in a) gallium atoms in 36.0 g gallium b) indium atoms in 36.0 g indium 3. a) Calculate the mass in grams, of mol of calcium nitrate. b) How many formula units of calcium nitrate are present? c) How many nitrate ions are present? 4. Carbon has two isotopes C-12 (99%) and C-13 (1%). a) How many atoms of C would be present in a 34 gram sample of pure diamond (pure carbon)? b) How many atoms of those are C-13 atoms? 5. A sample of Ni(CO) 4, a toxic transition-metal complex, has atoms of carbon. How many atoms of Ni does it contain? 6. How many grams of CO 2 are in 7.50 liters of CO 2 at STP? 7. Without doing any detailed calculations, rank the following samples in order of increasing number of atoms: 0.50 mol H 2O; 23 g Na; 6.0 x N 2 molecules. 8. A reaction produces grams of ammonia gas (NH 3). a) How many grams of N 2 must have reacted to produce this ammonia gas?

6 b) Assuming N 2 gas was the entire source of N and all of it was converted to ammonia, how many L of N 2 gas reacted assuming the reaction was carried out at STP conditions? b) How many L of ammonia were produced assuming the reaction was carried out at STP conditions? 9. Calculate the following quantities for 0.200L of a 0.400M Calcium Iodide (CaI 2) solution. a) moles of CaI 2 b) grams of CaI 2 required to prepare the solution b) moles of I What is the concentration (M) of a NaCl solution prepared by dissolving 9.3 g of NaCl in sufficient water to give 350 ml of solution? 11. a) How many moles of sodium ions are present in 150mL of a 0.75 M sodium phosphate solution? b) What is the molarity of sodium ions? Homework: 1. Answer the following questions for a 3.50g sample of C 6H 12O 6. a) What is the molar mass of this compound? b) How many moles are in the sample? c) How many hydrogen atoms are present in the sample? 2. a) Calculate the number of moles in 1.75 grams of sodium carbonate. b) How many formula units of sodium carbonate are present? c) How many sodium ions are present? 3. Boron has two isotopes B-10 (19.9%) and B-11 (80.1%). a) How many atoms of B would be present in a 50 gram sample of pure boron? b) How many atoms of those are B-10 atoms? 4. A sample of C 12H 22O 11 contains moles of carbon atoms. How many moles of hydrogen atoms are in the sample? 5. Without doing any detailed calculations, rank the following samples in order of increasing number of atoms: 3.0 x molecules H 2O 2; 2 mol CH 4; 32 g O 2 6. One component of smog is nitrogen monoxide, NO. A car produces about 8.0 g of this gas per day. What is the volume at STP? 7. A reaction produces 100 grams of water.

7 a) How many grams of H 2 must have reacted to produce this amount of water if 1 mol of H 2O is produced for every 1 mol of H 2 that reacts? b) Assuming H 2 gas was the entire source of H and all of it was converted to water, how many L of H 2 gas reacted assuming the reaction was carried out at STP conditions? c) How many molecules of H 2 reacted, assuming the reaction was carried out at STP conditions? 8. Calculate the following quantities for 343 ml of a 1.27M Na 2SO 4 solution. a) Moles of Na 2SO 4 b) grams of Na 2SO 4 required to prepare the solution b) moles of Na + 9. What is the molarity of a 750 ml solution containing 50.0 g KCl? 10. a) How many moles of hydroxide ions are present in 300mL of a 2.50M Ca(OH) 2 solution? b) What is the molarity of hydroxide ions? TEACHER KEY Atomic Theory and Models of the Atom Classwork: 1. An atom has 65 neutrons and a mass of 122 u. Write the proper nuclide symbol. 122 La 57

8 2. Atom A has 11 neutrons and Atom B also has 11 neutrons. Are these atoms isotopes? Explain. No! Isotopes will have differing numbers of neutrons. 3. Which component of Dalton s atomic theory reflects his understanding of the law of conservation of mass for chemical processes? Why? Atoms are rearranged in chemical processes, not created or destroyed. 4. The atomic masses of elements are generally not whole numbers. Explain why. The reported masses on the periodic table are averages of all of the isotopes of a particular element AND are standardized to C Gallium has two stable isotopes: Ga - 69 (68.92 u) and Ga-71 (70.92 u). Using the average atomic mass of gallium, what is the % abundance of the heavier of the two isotopes? 39.9% 5. Naturally occurring chlorine is 75.78% Cl - 35 ( u) and 24.22% Cl - 37 ( u). Calculate the average atomic mass u 7. What conclusions were made from Rutherford s Gold Foil Experiment? How did this experiment change the atomic model? The atom is mostly empty space with the positive protons densely packed together in the nucleus. Instead of having the electrons and protons mixed together, this had the electrons in orbit around the positively charged nucleus. 8. Explain why the Bohr model was insufficient and how the quantum model explained this deficiency. How is the electron viewed differently in each model? The Bohr model was not able to explain WHY the orbits were stable, the PES spectra of period 2 elements, and hyperfine spectral lines. The quantum model postulated stable orbitals IF we view the electron as a wave instead of as a particle. The quantum orbitals represent areas of high probability of finding an electron.

9 9. Consider the equations relating wavelength, frequency and energy of electromagnetic radiation. How is the energy of a photon related to its frequency and wavelength? The energy is inversely proportional to the wavelength and directly proportional to the frequency. 10. Calculate the frequency of an X ray that has a wavelength of 8.21 nm x /s 11. What is the frequency of a photon that has an energy of J 5.6 x /s 12. Provide a brief explanation for what each of the four quantum numbers describes. Principal Main energy level Azimuthal Orbital Magnetic Orientation of orbital Spin spin state of electron Homework: 1. Radioactive americium is used in household smoke detectors and in bone mineral analysis. a) Give the number of electrons, protons, and neutrons in a neutral atom of americium Protons = 95 Neutrons = 146 electrons = 95 b) Write the proper nuclide symbol. 241 Am What characteristics do atoms of carbon-12, carbon-13, and carbon-14 have in common? In what ways are they different? Same atomic number or number of protons. They each have different numbers of neutrons and atomic mass

10 3. Identify the isotope that has atoms with a) 117 neutrons, 77 protons, and 77 electrons Ir -177 b) 30 neutrons and an atomic mass of 58 Nickel How did the discovery of isotopes conflict with Dalton s atomic theory? Dalton postulated that atoms of the same element were all identical. Isotopes are atoms of the same element but differ in mass or # of neutrons. 5. The average mass of any large number of atoms of a given element is always the same for a given element. Explain. In a large sample, the number of atoms of each isotope will match the natural distribution or abundances of each. 6.. Naturally occurring boron is 19.9% B - 10 (mass = u) and 80.1% B - 11 (mass = u). Calculate the average atomic mass u 7. Uranium has an atomic mass equal to It consists of two stable isotopes: uranium -235 with an isotopic mass of u and uranium-238 with an isotopic mass of u. Calculate the % abundance of the uranium-235 isotope. 0.72% 8. How did Rutherford interpret the deflection of α-particles in his gold foil experiment? Did these findings support or disprove the plum pudding model of the atom? Explain. Rutherford believed the deflections were best explained by envisioning the protons being densely packed in a nucleus causing the deflection of the alpha particles. These findings did not support the plum pudding model as it predicted all alpha particles would move through the gold foil. 9. How does Bohr's model of the atom explain the existence of line spectra? How are spectral lines produced?

11 The Bohr model postulates discrete orbits where electrons can exist. The spectral lines are created when light is emitted when an electron moves from one orbit to a less energetic one. 10. What is the energy of a photon that has a wavelength of 8.33 x 10-6 m? 2.39 X J 11. What is the wavelength (in nm) of a photon that has an energy of J? 379 nm 12. How does the quantum model describe the location of an electron? The quantum model uses four numbers to represent the possible quantum states of an electron in the atom. These represent areas of high probability of locating the electron or in other words area of relatively high electron density. Periodic Table Classwork: 1. An element is found to gain three electrons when it forms an ion. a) What group number would this element be found in? Group 15 or 5A b) Is there enough information provided to determine what period it is in? No 2. Look at the average atomic mass of Ar and K.

12 a) Explain why early scientists might have been tempted to have K follow Cl on the periodic table. K is next if grouped by increasing atomic mass b) Propose two reasons as to why they placed Ar after Cl instead of K. K is not inert like the rest of the noble gases - Ar is. Secondly, Ar has the next highest atomic number, 1 less than K. 3. Identify the following elements: a) An alkali metal in the 5th period. Rb b) A transition metal Cr c) An atom in the 3rd period that forms a stable ion with a -1 charge. Cl 4. Explain why atoms tend to gain or lose electrons relative to the number of valence electrons. Atoms gain or lose electrons to obtain a full valence shell - which for most atoms is 8 (full s and p). 5. What ions are the following elements likely to form? a) Nitrogen N 3- b) Calcium Ca 2+ c) Sulfur S 2-6. Explain why the noble gases are inert (unreactive).

13 They have a full valence shell 7. Why are the charges of transition metals (d-block) difficult to predict? They can lose 2 electrons from their outermost s but then occasionally some of the d electrons are lost as well. 8. Write the formulas for the following binary ionic compounds. a) magnesium oxide MgO b) manganese(ii) chloride MnCl 2 c) calcium phosphide Ca 3P 2 d) copper(i) sulfide Cu 2S 9. Write the formulas for the following polyatomic ionic compounds. a) potassium sulfate K 2SO 4 b) aluminum phosphate AlPO 4 c) iron(iii) carbonate Fe 2(CO 3) 3 d) aluminum hydroxide Al(OH) Aluminum reacts with a certain nonmetallic element to form a compound with the general formula Al 2X 3. Element X must be from which group on the periodic table? Group 16 or 6A Homework:

14 1. What accounts for similarities of chemical properties for elements in the same group(family)? Same number of valence electrons 2. Provide the group names for the elements in Group 1, 2, 17 and 18. Provide and example of an element in each of the above groups. Group 1 = alkali metals Group 2 = alkaline earth metals Group 17 = Halogens Group 18 = noble gases 3. Identify the following elements: a) A halogen in the 3rd period. Cl b) A metalloid Si c) An atom in the 4th period that forms a stable ion with a +1 charge. K 4. Locate the following elements on the periodic table and indicate which orbital type(s) is occupied by its valence electrons a) Lithium 2s b) Silicon 3s and 3p c) Copper 4s 5. What ions are the following elements likely to form? a) Oxygen O 2- b) Sodium

15 Na + c) Bromine Br - 6. A main group element in Period 4 forms the molecular compound H 2E and the ionic compound Na 2E. a) To which group does the element belong? Group 16 or 6A b) Write the name and symbol of the element. Se 7. Write the formulas for the following binary ionic compounds. a) sodium sulfide Na 2S b) cobalt(ii) chloride CoCl 2 c) lithium nitride Li 3N d) Tin(IV) oxide SnO 2 8. Write the formulas for the following polyatomic ionic compounds. a) barium nitrate Ba(NO 3) 2 b) calcium phosphite Ca 3(PO 3) 2 c) iron(ii) chromate FeCrO 4 d) potassium permanganate KMnO 4

16 9. How many total ions (cations and anions) are present in the following ionic compounds? a) sodium acetate NaC 2H 3O 2 = 2 b) aluminum nitrate Al(NO 3) 3 = 4 c) Copper(II) chloride CuCl 2 = The most common charge associated with silver in its compounds is +1. Indicate the formulas you would expect for the ionic compounds formed between silver and ions of the following elements. a) iodine AgI b) sulfur Ag 2S c) phosphorous Ag 3P Mole Concept Classwork: 1. Answer the following questions for the compound aluminum sulfate. a) What is the molar mass of this compound? Al 2(SO 4) 3 = g/mol b) What is the mass of a 1.5 mole sample? 513 g c) How many oxygen atoms are present in the 1.5 mol sample 1.08 x O atoms 2. What mass of rhodium contains as many atoms as there are in a) gallium atoms in 36.0 g gallium 53.1 g b) indium atoms in 36.0 g indium 32.3 g

17 3. a) Calculate the mass in grams, of mol of calcium nitrate g b) How many formula units of calcium nitrate are present? 2.61 x formula units c) How many nitrate ions are present? 5.21 x nitrate ions 4. Carbon has two isotopes C-12 (99%) and C-13 (1%). a) How many atoms of C would be present in a 34 gram sample of pure diamond (pure carbon)? 1.71 x atoms C b) How many atoms of those are C-13 atoms? 1.71 x 1022 atoms C A sample of Ni(CO) 4, a toxic transition-metal complex, has atoms of carbon. How many atoms of Ni does it contain? 1.31 x 1024 atoms Ni 6. How many grams of CO 2 are in 7.50 liters of CO 2 at STP? 14.7 grams 7. Without doing any detailed calculations, rank the following samples in order of increasing number of atoms: 0.50 mol H 2O; 23 g Na; 6.0 x N 2 molecules. 23 g Na < 0.50 mol H 2O < 6.0 x N 2 molecules 8. A reaction produces grams of ammonia gas (NH 3). a) How many grams of N 2 must have reacted to produce this ammonia gas? grams b) Assuming N 2 gas was the entire source of N and all of it was converted to ammonia, how many L of N 2 gas reacted assuming the reaction was carried out at STP conditions? L

18 b) How many L of ammonia were produced assuming the reaction was carried out at STP conditions? 0.12 L ammonia 9. Calculate the following quantities for 0.200L of a 0.400M Calcium Iodide (CaI 2) solution. a) moles of CaI moles b) grams of CaI 2 required to prepare the solution b) moles of I grams moles I 10. What is the concentration (M) of a NaCl solution prepared by dissolving 9.3 g of NaCl in sufficient water to give 350 ml of solution? M 11. a) How many moles of sodium ions are present in 150mL of a 0.75 M sodium phosphate solution? moles Na b) What is the molarity of sodium ions? 2.25 M Homework: 1. Answer the following questions for a 3.50g sample of C 6H 12O 6. a) What is the molar mass of this compound? 180 g/mol b) How many moles are in the sample? moles c) How many hydrogen atoms are present in the sample?

19 1.4 x atoms H 2. a) Calculate the number of moles in 1.75 grams of sodium carbonate moles b) How many formula units of sodium carbonate are present? 9.9 x formula units c) How many sodium ions are present? 1.98 x sodium ions 3. Boron has two isotopes B-10 (19.9%) and B-11 (80.1%). a) How many atoms of B would be present in a 50 gram sample of pure boron? 2.78 x atoms B b) How many atoms of those are B-10 atoms? 5.54 x atoms B A sample of C 12H 22O 11 contains moles of carbon atoms. How many moles of hydrogen atoms are in the sample? moles H 5. Without doing any detailed calculations, rank the following samples in order of increasing number of atoms: 6.0 x molecules H 2O 2; 2 mol CH 4; 32 g O 2 32 g O 2 < 6.0 x molecules H 2O 2 < 2 mol CH 4 6. One component of smog is nitrogen monoxide, NO. A car produces about 8.0 g of this gas per day. What is the volume at STP? 5.97 L 7. A reaction produces 100 grams of water. a) How many grams of H 2 must have reacted to produce this amount of water if 1 mol of H 2O is produced for every 1 mol of H 2 that reacts? 11.1 grams H 2

20 b) Assuming H 2 gas was the entire source of H and all of it was converted to water, how many L of H 2 gas reacted assuming the reaction was carried out at STP conditions? L H 2 c) How many molecules of H 2 reacted, assuming the reaction was carried out at STP conditions? 3.3 x molecules H 2 8. Calculate the following quantities for 343 ml of a 1.27M Na 2SO 4 solution. a) Moles of Na 2SO moles b) grams of Na 2SO 4 required to prepare the solution grams b) moles of Na moles 9. What is the molarity of a 750 ml solution containing 50.0 g KCl? M 10. a) How many moles of hydroxide ions are present in 300mL of a 2.50M Ca(OH) 2 solution? 1.5 moles b) What is the molarity of hydroxide ions? 5 M