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electron within the orbital Definitions of numbers 1. Principal Quantum Number - n - This number describes the energy level that the electron occupies. It can have a value of 1-7 – This defines the "level" of the electron. X 2. Orbital Quantum Number – I – (Azimuthal) this number describes the shape of the orbital that the electron is found in. It can have a value from 0-3. This defines the "sublevel" of the electron. Also, the numbers can be replaced by letters according to the following: a. b. 0=s 1 = p 2= d 3 = f C. d. f orbital shapes: x Z Z 3. Magnetic Quantum Number - m₁ - this number describes the orientation of the electrons in the orbitals. This defines the "orbital" of the electron. There are 21+1 orbitals in each sublevel. This quantum number can have the following values: (-I to +I) a. b. C. d. If I = 0, m₁ can equal 0 If I = 1, m, can equal −1, 0, +1 If I = 2, m₁ can equal −2, -1, 0, +1, +2 If I = 3, m, can equal −3, -2, -1, 0, +1, +2, +3 4. Spin Quantum Number - m - this number describes the direction of spin of the electron in the orbital – electrons in the same level and sublevel must spin in opposite directions. This can have a value of +1/2 or −1/2 only. で Principal energy level 2 3 5 6 Sublevels sublevel available (2€ + 1) 1 1 3 S 8 р S S S S P Number of Total Number of electrons electrons orbitals in possible in possible for sublevel energy level [2(2€ + 1}] h# 1 3 5 1 3 5 7 13579 1 9 11 2 2 6 2 6 10 2 6 10 14 2 6 10 14 18 2 6 10 14 18 22 *These orbitals are not used in the ground state of any known element. 2 8 18 32 50 72 iv. According to the Pauli Exclusion Principle, no two electrons can have the same four quantum numbers in the same atom. Think of these as City, Street, House Number, and upstairs/downstairs apartment. No two people could have th same complete address, but they could live in the same city, on the same street, or even in the same house, but not the same apartment. V. W b. Orbital diagrams and electron configurations are models for electron arrangements. i. Orbital diagrams are used to show how electrons are distributed among the different sublevels and also to show the direction of spin. ii. For orbital diagrams, you must fill in orbitals in the same energy level with one electron each before pairing up any electrons. This is known as Hund's Rule. iii. Electron configurations are used to show similar information, but are a much more abbreviated form. How many electrons can go in any level? (Maximum) S = 2 iv. 1. 2. 3. 4. P = 6 d = 10 f = 14 13 25 3s 4s 5s 68 75 V. 2P 3p 4p 5p 6p 7p vii. What order do I fill the levels in? The Aufbau Principle states that when predicting an atoms ground state electron configuration, electrons will occupy the lowest energy orbital available first. 3d 4d 41 5d 5f ód This also could be written: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p 90004 2p 3p Number of Electrons Determine the Order of Filling Orbitals 3d 2P 28 3d 3p 38 2 4f 5f Ad 5d 6d Ap 5p 6p 48 58 68 Ap 7p 7s 4d 70 C. Electron configurations can be written in terms of noble gases i. Instead of writing out the long configurations that some of the larger elements would have, you can abbreviate by using the next smallest noble gas to the element in question to replace most of the electron configuration. ii. Only noble gases can be used for this. Don't replace part of an electron configuration with any other element. t iii. Example Configurations with the noble gas shortcut: 1. Cl 2. W 3. Ra 4. K 5. Zn 6. At 7. Cf III. Writing Lewis Structures or Lewis Dot Diagrams for elements a. b. This is a kind of short hand that illustrates how many outer shell electrons an atom contains. The purpose behind all of the configurations is because the number of electrons and their placement in the atom, strongly influences how the atom will react, bond and the properties it will demonstrate. C. Rules for writing dot diagrams: i. Write configuration. ii. How many e- are in the outer energy level? iii. Write the elements symbol. iv. Draw dots around the symbol to represent outer level electrons, each of the 4 sides represents an orbital. V. "s" electrons must be paired (1st two e-) vi. Other three sides cannot be paired until each has at least one e-. (Hund's Rule) o O O X O O "X" is being used to represent any possible element symbol. The circles are the possible placement of outer shell electrons. You would darken the dots for as many would apply to your element. で d. Example: ·Ö: e. Dot diagram examples: i. C ii. Br iii. Ar iv. H V. Mg vi. Ag vii. P viii. O IV. Exceptions to electron configuration using the Aufbau Diagram A half full level is the next stable thing to a full level. a. b. C. d. Some atoms will violate our predictions in order to achieve stability. This can occur in the transition metals when the predicted configuration ends in a d4 or d9. It will steal a single electron from the full s shell that came before it to obtain 2 half full shells or one half and one full shell. (s2 d4) becomes (s1 d5) and (s2 d9) becomes (s1 d10) e. Actual exceptions: * 5d1 fills before starting the 4f sequence * 6d1 fills before starting the 5f sequence Predicted configurations Cr:[Ar]4s2, 3d4 Cu:[Ar] 4s2, 3d9 Nb:[Kr]5s2,4d3 Mo: [Kr] 5s2, 4d4 Tc:[Kr] 5s2, 4d5 Ru[Kr] 5s2, 4d6 Rh[Kr] 5s2, 4d7 Pd[Kr] 5s2, 4d8 Ag[Kr] 5s2, 4d9 Pt[Xe] 6s2, 4f14, 5d8 Au[Xe] 6s2, 4f14, 5d9 Actual configurations Cr:[Ar] 4s1, 3d5 Cu[Ar] 4s1, 3d10 Nb:[Kr] 5s1, 4d4 Mo[Kr] 5s1, 4d5 Tc[Kr] 5s1, 4d6 Ru[Kr] 5s1, 4d7 Rh[Kr] 5s1, 4d8 Pd[Kr] 5s0, 4d10 Ag[Kr] 5s1, 4d10 Pt[Xe]6s1, 4f14, 5d9 Au[Xe] 6s1, 4f14, 5d10 Questions: 1. Make a chart, with the following columns: Quantum number name, symbol, possible values. Fill in the information for each of the four quantum numbers. 2. What is the reason that an element cannot have all four quantum numbers the same? 3. What is the rule which means "spread them out before you pair them up"? Distilling Information 1. Label the s, p, d, and f blocks in Table 3-4. 2. b. 3. Which guideline, Hund's rule or Pauli's exclusion principle, is violated in the following orbital diagrams? 1s2 ↑↓ 182 ↑ c. d. 28² ↑↓ 28² NNN 2p NN Table 3-4 Orbital Blocks of the Periodic Table 2p4 38² [Rn] 7s²5f²6d¹ e. [Kr] 5s24d105p4 List the element represented by each of the following electron configurations. a. 1s22s22p63s¹ b. 1s²2s²2p63s²3pᵒ4s²3dº 1s²2s22p63s²3p64s23d¹04p65s²4d¹ a. b. 4. List the element represented by each of the following orbital diagrams. N N N 3p a. b. c. 1s d. a. 1s b. 18 c. N 18 d. N 28 N 28 28 18 e. N NNN 4s motummurnaremogo 2s NNN 2p N NNN 2p 2s NNN 3s 2p NNN 2p 3s N 3s 3s NNN 3p NNN namumun 2p 3s ↑ 3p 3p NNN 3p 4s ↑↓ 48 NNNN 3d NNNNN 3d ઉત 4p VALENCE ELECTRONS The valence electrons are the electrons in the outermost principal energy level. They are always "s" or "s and p" electrons. Since the total number of electrons possible in s and p sublevels is eight, there can be no more than eight valence electrons. Determine the number of valence electrons in the atoms below. 1. fluorine 2. phosphorus 3. calcium 4. nitrogen 5. iron 6. argon 7. potassium 8. helium 9. magnesium 10. sulfur Example: carbon Electron configuration is 1s² 2s²2p² Carbon has 4 valence electrons. 11. lithium 12. zinc 13. carbon 14. iodine 15. oxygen 16. barium Name 17. aluminum 18. hydrogen 19. xenon 20. copper Name CHAPTER 5 atomic emission spectrum higher Section 5.2 Quantum Theory and the Atom In your textbook, read about the Bohr model of the atom. Use each of the terms below to complete the statements. Date electron energy levels STUDY GUIDE FOR CONTENT MASTERY frequencies lower 1. The lowest allowable energy state of an atom is called its 2. Bohr's model of the atom predicted the hydrogen's atomic emission spectrum. 3. According to Bohr's atomic model, the smaller an electron's orbit, the the atom's energy level. 4. According to Bohr's atomic model, the larger an electron's orbit, the the atom's energy level. h my 5. Bohr proposed that when energy is added to a hydrogen atom, its _____ moves to a higher-energy orbit. Class ground state of the lines in 6. According to Bohr's atomic model, the hydrogen atom emits a photon corresponding to the difference between the associated with the two orbits it transitions between. 7. Bohr's atomic model failed to explain the other than hydrogen. In your textbook, read about the quantum mechanical model of the atom. Answer the following questions. 8. If you looked closely, could you see the wavelength of a fast-moving car? Explain your answer. of elements 9. Using de Broglie's equation, λ = which would have the larger wavelength, a slow-moving proton or a fast-moving golf ball? Explain your answer. Name CHAPTER 5 Section 5.2 continued Date STUDY GUIDE FOR CONTENT MASTERY In your textbook, read about the Heisenberg uncertainty principle. For each item in Column A, write the letter of the matching item in Column B. Column A 10. The modern model of the atom that treats electrons as waves 11. States that it is impossible to know both the velocity and the position of a particle at the same time 12. A three-dimensional region around the nucleus representing the probability of finding an electron 13. Originally applied to the hydrogen atom, it led to the quantum mechanical model of the atom a. Class Column B Heisenberg uncertainty principle b. Schrödinger wave equation quantum mechanical model of the atom d. atomic orbital Answer the following question. 14. How do the Bohr model and the quantum mechanical model of the atom differ in how they describe electrons? In your textbook, read about hydrogen's atomic orbitals. In the space at the left, write the term in parentheses that correctly completes the statement. 15. Atomic orbitals (do, do not) have an exactly defined size. 16. Each orbital may contain at most (two, four) electrons. 17. All s orbitals are (spherically shaped, dumbbell shaped). 18. A principal energy has (n, n²) energy sublevels. 19. The maximum number of (electrons, orbitals) related to each principal energy level equals 2n². 20. There are (three, five) equal energy p orbitals. 21. Hydrogen's principal energy level 2 consists of (2s and 3s, 2s and 2p) orbitals. 22. Hydrogen's principal energy level 3 consists of (nine, three) orbitals. で Name CHAPTER 5 Aufbau principle lowest Section 5.3 Electron Configurations In your textbook, read about ground-state electron configurations. Use each of the terms below just once to complete the passage. (1) that gives the atom the (2). of electrons is the most (3). atom's (4). electron configuration Pauli exclusion principle The arrangement of electrons in an atom is called the atom's Complete the following table. Element 9. Helium STUDY GUIDE FOR CONTENT MASTERY Three rules define how electrons can be arranged in an atom's orbitals. The 10. 11. Neon Date (5). states that each electron occupies the lowest energy states that a maximum of two orbital available. The (6). electrons may occupy a single atomic orbital, but only if the electrons have opposite (7) (8). states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins occupy the same orbitals. .. Electrons in an atom tend to assume the arrangement possible energy. This arrangement arrangement and is called the Atomic Number 7 ground-state electron configuration Hund's rule spins stable 1s Class Orbitals 2s 2px 2py 2pz TL TL TL TL TL Electron Configuration 15² Name CHAPTER 5 Section 5.3 continued Date Answer the following questions. 12. What is germanium's atomic number? How many electrons does germanium have? STUDY GUIDE FOR CONTENT MASTERY 13. What is noble-gas notation, and why is it used to write electron configurations? 14. Write the ground-state electron configuration of a germanium atom, using noble-gas notation. Class In your textbook, read about valence electrons. Circle the letter of the choice that best completes the statement or answers the question. 15. The electrons in an atom's outermost orbitals are called a. electron dots. b. quantum electrons. c. valence electrons. d. noble-gas electrons. 16. In an electron-dot structure, the element's symbol represents the a. nucleus of the noble gas closest to the atom in the periodic table. b. atom's nucleus and inner-level electrons. c. atom's valence electrons. d. electrons of the noble gas closest to the atom in the periodic table. 17. How many valence electrons does a chlorine atom have if its electron configuration is [Ne]3s23p5? a. 3 a. valence electrons b. inner-level electrons b. 21 c. 5 d. 7 18. Given boron's electron configuration of [He]2s²2p¹, which of the following represents its electron-dot structure? a. Be. b. .B. c. B: d. Be 19. Given beryllium's electron configuration of 1s22s², which of the following represents its electron-dot structure? a. Be. d. Be b. .B. c. B: 20. Which electrons are represented by the dots in an electron-dot structure? c. only s electrons d. both a and c