AP Chemistry Test Preview: Atomic 9. Which of the following properties generally Theory & Periodicity decreases across the periodic table from lithium to fluorine? Questions 1-4 refer to neutral atoms for which the (A) First ionization energy atomic orbitals are represented below. (B) Atomic mass (C) Electronegativity (D) Maximum value of the oxidation number (E) Atomic radius 10. The effective nuclear charge experienced by the outermost electron of Na is different than the effective nuclear charge experienced by the outermost electron of Ne. This difference best accounts for which of the following? (A) Na has a greater density at STP than Ne. (B) Na has a higher electronegativity than Ne. (C) Na has a higher melting point than Ne. (D) Na atoms require more energy to become 1– ions than Ne atoms. (E) Na atoms require less energy to become a 1+ ion than 1. Atom that is NOT in the ground state. Ne atoms 2. Metal that is commonly found as a 3+ ion. 3. Has the highest electron affinity. 4. Forms weak acid when combined with hydrogen. Question 11 refers to the following types of energy. Questions 5-6 refer to the atoms of the following elements. Assume that the atoms are in the ground state. (A) Activation energy (B) Free energy (A) S (C) Ionization energy (B) C (D) Electron affinity (C) Ga (E) Lattice energy (D) Sb (E) Br 11. The energy required to convert a ground-state atom 5. Non-metal atom that contains exactly one unpaired in the gas phase to a gaseous negative ion electron Questions 12-15 refer to atoms for which the occupied 6. The atom that contains only one electron in the atomic orbitals shown below. highest occupied energy sublevel. 7. In which of the following groups are the three species isoelectronic; i.e., have the same number of electrons? (A) Mg2+, Ca2+, Sr2+ (B) Ne, Ar+, Kr2+ (C) O2-, S2-, Cl- (D) S2-, Cl–, Ar (E) Li, Na, K 12. Represents an excited hydrogen atom. 8. The atomic mass of neon is 20.18. Given that only two naturally occurring isotopes of neon occur in 13. Represents a noble gas atom. abundance, 20Ne and 22Ne, the natural abundance of the 20Ne isotope must be approximately 14. Represents a ground state atom of iron. (A) 90 % (B) 70 % 15. Represents a metal atom that would exhibit (C) 50 % paramagnetism. (D) 25 % (E) 10 % Ionization Energies for element X (kJ mol¯1) 23. Which of the following sets of quantum numbers (n, First Second Third Fourth Fifth l, ml, ms) best describes the valence electron of 801 2427 3660 25,025 32,822 highest energy in a ground-state potassium atom (atomic number 19) ? 16. The ionization energies for element X are listed in (A) 4, 0, 0, 1/2 the table above. On the basis of the data, element X (B) 4, 0, 1, 1/2 is most likely to be (C) 4, 1, 1, 1/2 (A) Li (D) 4, 1, 2, 1/2 (B) Be (E) 4, 2, 0, 1/2 (C) B (D) C 24. The electron-dot structure (Lewis structure) for (E) N which of the following molecules would have one unshared pair of electrons on the central atom? 17. In the periodic table, as you move down column 7A (A) H2S (or 17 = the halogens) what happens to the atomic (B) NH3 radii? (C) CH4 (A) It remains constant. (D) HCN (B) It increases only. (E) CO2 (C) It increases, then decreases. (D) It decreases only. Ionization Energies for Element X (E) It decreases, then increases. Ionization Ionization Energy (kJ/mol) 1st 787 18. Which of the following is a conclusion drawn from 2nd 1,580 Millikan’s experiments in which charged droplets of 3rd 3,200 oil are observed and their speed while passing 4th 4,400 through an electric field is measured? 5th 16,000 (A) Atoms have equal numbers of positive and 6th 20,000 negative charges. 7th 24,000 (B) Electrons in atoms are arranged in shells. (C) The value of negative electric charges is a 25. The first seven ionization energies of element X are fundmental unit equal to 1.6 x 10–19 coulomb. shown in the table above. On the basis of these data, (D) electrons and protons in atoms have equal element X is most likely a member of which of the but opposite charges. following groups (families) of elements? (E) Electrons reside in a “cloud” that surrounds (A) Alkali earth metals the positively charged nucleus. (B) Boron group (D) Nitrogen group (C) Carbon group (E) Halogen group Questions 15-18 refer to the following list. 26. In which of the following are the chemical species (A) Heisenberg uncertainty principle correctly ordered from smallest radius to largest (B) Pauli exclusion principle radius? (C) Hund's rule (principle of maximum multiplicity) (A) B < C < N (D) Shielding effect (B) Ar < Xe < Kr (D) Na < Na+ < K 2- (E) Aufbau principle (C) Cl < S < S (E) K+ < Ca2+ < K 19. Indicates that an atomic orbital can hold no more 27. Of the following elements, which would be expected than two electrons to have chemical properties most similar to those of nitrogen, N? 20. Hypothetical “building up” of a atom’s electron (A) Br configuration by adding subatomic particles to the (B) Cl (D) P appropriate locations one at a time (C) S (E) Se 21. Can be used to predict that a gaseous nitrogen atom in its ground state is paramagnetic 22. Helps to explain the fact that valence electrons are less tightly bound to an atom than electrons in lower energy levels AP Chemistry Take Home FRQs: Atomic Structure & Periodicity 2007B.2. Answer the following problems about gases. (a) The average atomic mass of naturally occurring neon is 20.18 amu. There are two common isotopes of naturally occurring neon as indicated in the table below. Isotope Mass (amu) Ne-20 19.99 Ne-22 21.99 i. Using the information above, calculate the percent abundance of each isotope. ii. Calculate the number of Ne-22 atoms in a 12.55 g sample of naturally occurring neon. (b) A major line in the emission spectrum of neon corresponds to a frequency of 4.34 x 10 14 s-1. Calculate the wavelength, in nanometers, of light that corresponds to this line. (c) In the upper atmosphere, ozone molecules decompose as they absorb ultraviolet (UV) radiation, as shown by the equation below. Ozone serves to block harmful ultraviolet radiation that comes from the Sun. O3(g) O2(g) + O(g) UV A molecule of O3(g) absorbs a photon with a frequency of 1.00 x 10 15 s-1. i. How much energy, in joules, does the O3(g) molecule absorb per photon? ii. The minimum energy needed to break an oxygen-oxygen bond in ozone is 387 kJ mol-1. Does a photon with a frequency of 1.00 x 1015 s-1 have enough energy to break this bond? Support your answer with a calculation. 2006.8. Suppose that a stable element with atomic number 119, symbol Q , has been discovered. (a) Write the ground-state electron configuration for Q, showing only the valence-shell electrons. (b) Would Q be a metal or nonmetal? Explain in terms of electron configuration. (c) On the basis of periodic trends, would Q have the largest atomic radius in its group or would it have the smallest? Explain in terms of electronic structure. (d) What would be the most likely charge of the Q ion in stable ionic compounds? (e) Write a balanced equation that would represent the reaction of Q with water. (f) Assume that Q reacts to form a carbonate compound. (i) Write the formula for the compound formed between Q and the carbonate ion, CO 32 . (ii) Predict whether or not the compound would be soluble in water. Explain your reasoning. 2000.7. Answer the following questions about the element selenium, Se (atomic number 34). (a) Samples of natural selenium contain six stable isotopes. In terms of atomic structure, explain what these isotopes have in common, and how they differ. (b) Write the complete electron configuration (e.g., 1s2 2s2 … etc.) for a selenium atom in the ground state. Indicate the number of unpaired electrons in the ground-state atom, and explain your reasoning. (c) In terms of atomic structure, explain why the first ionization energy of selenium is i) less than that of bromine (atomic number 35), and ii) greater than that of tellurium (atomic number 52). (d) Selenium reacts with fluorine to form SeF4. Draw the complete Lewis electron-dot structure for SeF4 and sketch the molecular structure. Indicate whether the molecule is polar or nonpolar, and justify your answer. 2006B.7. Account for each of the following observations in terms of atomic theory and/or quantum theory. (a) Atomic size decreases from Na to Cl in the periodic table. (b) Boron commonly forms molecules of the type BX3. These molecules have a trigonal planar structure. (c) The first ionization energy of K is less than that of Na. (d) Each element displays a unique gas-phase emission spectrum. 2007B.6. First Ionization Second Ionization Third Ionization Energy (kJ mol-1) Energy (kJ mol-1) Energy (kJ mol-1) Element 1 1251 2300 3820 Element 2 496 4560 6910 Element 3 738 1450 7730 Element 4 1000 2250 3360 The table above shows the first three ionization energies for atoms of four elements from the third period of the periodic table. The elements are numbered randomly. Use the information in the table to answer the following questions. (a) Which element is most metallic in character? Explain your reasoning. (b) Identify element 3. Explain your reasoning. (c) Write the complete electron configuration for an atom of element 3. (d) What is the expected oxidation state for the most common ion of element 2? (e) What is the chemical symbol for element 2? (f) A neutral atom of which of the four elements has the smallest radius?