Name period AP chemistry Unit 2 worksheet Practice problems

Transcription

1 Name period AP chemistry Unit 2 worksheet Practice problems 1. What are the SI units for a. Wavelength of light b. frequency of light c. speed of light Meter hertz (s -1 ) m s -1 (m/s) 2. T/F (correct the statement if it is false) a. Visible light is a form of electromagnetic radiation. True b. The frequency of radiation increases as the wavelength increases. False, the frequency decreases as wavelength increases c. Ultraviolet light has a shorter wavelength than visible light. True d. Electromagnetic radiation and sound waves travel at the same speed. False, electromagnetic radiation travels at the speed of light 3. What is the wavelength of radiation that has a frequency for 5.11 x s -1? Would this be visible to the human eye? 5.87 x 10-4 m; no 4. Exited mercury atoms emit light at 489 nm. What is the frequency of this radiation? Predict the color associated with it x s -1 ; blue 5. Calculate the smallest increment of energy that can be emitted or absorbed at a wavelength of 812 nm x J 6. The most prominent line in the spectrum of neon is found at nm. Other lines are found at nm, nm, nm, and nm. Which of these lines represents the most energetic light? at nm 7. Is energy emitted or absorbed when the following electronic transitions occur in hydrogen? a. From n=4 to n=2 Emitted b. From an orbit of radius 2.12 A to one of radius 8.48 A. Absorbed 8. What are the similarities and differences between the hydrogen 1s and 2s orbitals? Same spherical shape, but 2s has a larger radial extension than the 1s 9. List in order of increasing energy: 4f, 6s, 3d,1s,2p 1s, 2p, 6s, 4f 10. Explain why the effective nuclear charge experienced by a 2s electron in boron is greater than that for the 2p electron. The 2p electron in boron is shielded from the full charge of the nucleus by the 2s electrons, so the 2p electron experiences a smaller effective nuclear charge

2 11. Explain why the effective nuclear charge experienced by a 2s electron in aluminum is greater than that for the 2s electron experienced by boron. Aluminum has more protons than boron so the 2s electron will experience a greater effective nuclear charge 12. Which should experience the greater nuclear charge, a 2p electron in oxygen or a 2p electron in neon? A 2p electron in neon experiences a greater effective nuclear charge 13. How many f orbitals have n=3? Two electrons in an atom both occupy the 1s orbital. What quantity must be different for the two electrons? They must have opposite spins 15. How many unpaired electrons are there in an atom of tin in its ground state? Of the following elements, which one is most likely to form an ion through the loss of two electrons? a. strontium b. sulfur c. sodium d. chlorine e. aluminum 17. An atom has two electrons with principal quantum number (n) = 1, eight electrons with principal quantum number (n) = 2 and seven electrons with principal quantum number (n) = 3. From this data, supply the following values (if insufficient information is given, say so). (a) The mass number. not enough info (b) The atomic number. 17 (c) The electron configuration. _1s 2 2s 2 2p 6 3s 2 3p What is the maximum number of electrons that can occupy each of the following a. 3d 10 b. 4s 2 c. 2 nd shell 8 d. n=3 18 e. 2p 6 f. 5f 14 g. One 2p orbital 2 h. n= Write the orbital notation (can use noble gas) for each of the following a. Sc b. Si [Ar] 4s 3d [Ne] 3s 3p c. Sn d. Mn _ _ _ _ _ [Kr] 5s 4d 5p [Ar] 4s 3d 20. Write the noble gas configuration for the following a. Rb b. Se c. Zn [Kr]5s 1 [Ar]4s 2 3d 10 4p 4 [Ar]4s 2 3d 10 d. Pb e. Mn f. N [Xe]6s 2 5d 10 4f 14 6p 2 [Ar]4s 2 3d 5 [He]2s 2 2p Write the full electronic configuration for argon 1s 2 2s 2 2p 6 3s 2 3p Identify the element from the electron configurations of atoms shown below. (3) (a) [Ne] 3s 2 3p 2 Si (b) [Ar] 4s 2 3d 7 Co (c) [Xe] 6s 2 Ba

3 23. Which element could be represented by the complete PES spectrum to the right? A. Li B. B C. N D. Ne 24. Which of the following best explains the relative positioning and intensity of the 2s peaks in the following spectra? a)be has a greater nuclear charge than Li and more electrons in the 2s orbital b)be electrons experience greater electron-electron repulsions than Li electrons c)li has a greater pull from the nucleus on the 2s electrons, so they are harder to remove d)li has greater electron shielding by the 1s orbital, so the 2s electrons are easier to remove 25. Which will be closer to the nucleus, the n=3 electron shell in Ar or the n=3 shell in Kr? Kr 26. Arrange the following atoms in order of increasing atomic radius: F, P, S, As and explain why. F, S, P, As (atoms get bigger when a shell is added or less protons in the same number of shells) 27. Arrange the following atoms in order of increasing atomic radius: Al, Nb, Se, F, Mn and explain why. F, Al, Se,Mn, Nb, (atoms get bigger when a shell is added or less protons in the same number of shells) 28. An element having the configuration [Xe]6s 1 belongs to the group: a. alkaline earth metals b. alkali metals c. halogens d. noble gases e. none of these 29. What is the trend in the first ionization energy as one proceeds down group 1? Explain how this relates to size of the atoms. It decreases, the atoms have more shells as you go down a group so they have a larger radius and the nucleus does not hold on to them as well. 30. Arrange the following pure solid elements in order of increasing electrical conductivity: P, Ag, and Sb P, Sb, Ag 31. Explain in terms of electron configurations, why hydrogen exhibits properties similar to both lithium and fluorine It has one valence electron like lithium, but only needs one valence electron to have a full shell like fluorine 32. Which of the following statements are true a. All are false b. the first ionization energy of fluorine is greater than the first ionization energy of oxygen c. as the atomic number increases within a group of the main group elements, the tendency is for first ionization energy to increase d. it is easier to remove an electron from Na + than from Na. e. all particles with the electron configuration [Ar]4s 2 have the same ionization energy. 33. Consider the element Scandium, atomic # 21. (a) If the electronic configuration of the element were constructed "from scratch", into which orbital (and into which shell) would the final electron be placed? 3d (b) When scandium forms an ion with a charge of +1, from which orbital (and from which shell) would the electron be removed? 4s

4 34. Based on their position on the periodic table, predict which atom of the following pairs will have the largest first ionization energies. In each case explain with electron configuration and effective nuclear charge a. O, Ne b. Mg, Sr c. K, Cr d. Br, Sb e. Ga, Ge Ne Mg Cr Br Ge Smaller atoms have a harder time losing their electrons because the valence electrons feel a greater effective nuclear charge so it takes more energy to remove the electron. 35. For each pair, which element will have greater metallic character a. Li or Be b. Li or Na c. Sn or P 36. Predict whether each of the following oxides is ionic or molecular: SO 2, MgO, Li 2 O, N 2 O, XeO 3 Molecular, ionic, ionic, molecular, molecular 37. Identify two positive and two negative ions that are isoelectronic with argon. (4) (a) Two Positive ions _K + Ca 2+ (b) Two Negative ions Cl - S Compare the elements sodium and magnesium with respect to the following properties a. Electron configuration 1s 2 2s 2 2p 6 3s 1 ; 1s 2 2s 2 2p 6 3s 2 b. Most common ionic charge+1; +2 c. First ionization energy magnesium has a higher first ionization energy d. Atomic radius magnesium is smaller than sodium 39. Compare the elements fluorine and chlorine with respect to the following properties a. Electron configuration b. Most common ionic charge c. Atomic radius 1s 2 2s 2 2p 5 ; 1s 2 2s 2 2p 6 3s 2 3p 5-1;-1 Chlorine is larger than fluorine 40. Why are monatomic cations smaller than their corresponding neutral atom? Lost one electron so the remaining electrons have less repulsion and a greater effective nuclear charge 41. Write the noble gas configuration a. Fe 3+ b. Ni 2+ [Ar]3d 5 [Ar]3d Which neutral atom is isoelectric with each of the following a. Cl - b. Se 2- c. Mg 2+ Ar Kr Ne 43. Arrange the atoms and ions in each of the following sets in order of increasing size a. Br -, Na +, Mg 2+ b. Ar, Cl -, S 2-, K + Mg, Na, Br K, Ar, Cl, S 44. What is a covalent bond? A bond that forms when atoms share electrons 45. What is an ionic bond? A bond that forms when atoms give and take electrons 46. What is a metallic bond? A bond that forms when nuclei are attracted to a sea of electrons 47. Why can metals conduct electricity? There are electrons moving around 48. Using the periodic table, select the most electronegative atom in each of the following sets a. B, Be, C, Si b. Zn, Ga, Ge, As c. Na, Mg, K, Ca C As Mg 49. Label each of the following as ionic, metallic, or covalent a. NaOH b. N 2 O c. KCl d. HF e. O 2 f. Al foil

5 ionic covalent ionic covalent covalent metallic 50. Which of the following forms molecules? a. K 2 CO 3 b. F 2 c. BaCl 2 d. H 2 O e. Fe 2 O How many protons, neutrons, and electrons are in the following a. 65 Zn 2+ b. 40 Ar c. 14 N 3- d. 23 Na + 30,35,28 18,22,18 7,7,10 11,12, Which ions are cations in the previous problem, which are anions? A,d 53. How is bonding in Cl 2 different than NaCl? In Cl 2, electrons are being shared, and in NaCl sodium gives an electron to chlorine 54. How many valence electrons does each of the following atoms have? a. C b. Ca c. H d. Pb e. Ar f. Cl The ionization energies for an element are listed below First second third fourth fifth 8 ev 15eV 80eV 109eV 141 ev Based on the ionization energies, the element is most likely to be a. Sodium b. magnesium c. aluminum d. silicon e. phosphorus 56. Which of the following contains only atoms that are diamagnetic in their ground state? a. Kr, Ca, and P b. Ne, Be, and Zn c. Ar, K, and Ba d. He, Sr, and C 57. Which of the following is the electron configuration of an excited atom that is likely to emit a quantum of energy? (A) 1s 2 2s 2 2p 6 3s 2 3p 1 (B) 1s 2 2s 2 2p 6 3s 2 3p 5 (C) 1s 2 2s 2 2p 6 3s 2 (D) 1s 2 2s 2 2p 6 3s 1 3p The bond energy of fluorine in 159 kj mol -1. i. Determine the energy, in J, of a photon of light needed to break an F-F bond x J ii. Determine the frequency of this photon in s x s -1 iii. Determine the wavelength of this photon in nanometers 750 nm b. Barium imparts a characteristic green color to a flame. The wavelength of this light is 551 nm. Determine the energy involved in kj/mol 220 kj/mol Review 59. Which of the following species contain more electrons than neutrons? a. 2 H b. 11 B c. 16 O 2- d. 19 F How many protons, neutrons, and electrons are in an 56 26Fe atom? Protons Neutrons Electrons a b c d Calculate the following to the correct number of significant figures. a.1.27g/5.296cm 3 b. 12.2mL mL c g g d. 0.1 m x 3.21m g/ml 12.6 ml g 0.3 m The density of pure silver is 10.5 g/cm 3. If 5.25 g of pure silver pellets are added to a graduated cylinder containing 11.2 ml of water, to what level will the water in the cylinder rise? 11.7 ml

6 63. Let s pretend you are holding two atoms of carbon that are isotopes. Describe what the two atoms have in common and what they have different. They have the same number of protons, but one would have more mass than the other one. 64. What is the mass, in grams, of 1.75 x molecules of caffeine, C 8 H 10 N 4 O 2? g 65. Determine the empirical formula of the compound with the following compositions by mass 10.4 percent C, 27.8 percent S, and 61.7 percent Cl CSCl Write a balanced net ionic reaction and label the reactants and products as weak, non, or strong electrolytes a. Silver nitrate + calcium chloride 2AgNO 3 + CaCl 2 2AgCl + Ca(NO 3 ) 2 2Ag + + 2Cl - 2AgCl Strong strong weak b. Hydrosulfuric acid + magnesium H 2 S + 2Mg 2MgS + H 2 Weak weak non c. Solid sodium oxide + water Na 2 O + H 2 O Na + + OH - Non strong