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Name: ____________________________________________________________________________________ UNIT 3 Particle Composition, Pt. 1: Atoms What’s in an atom of an element? How is it arranged? Ongoing questions | How are the properties of invisible particles responsible for visible changes? | What are particles and how can we model their physical behavior? The configuration of subatomic particles within an atom is responsible for the atom’s identity, chemical and physical properties, and behavior. October 10 – October 27, 2016 Quizzes: _________________________________________ Test date: ________________________________________ Key topics and vocabulary Key scientific skills Atomic model development: the scientists o Democritus and Dalton o Thomson o Rutherford o Bohr o Schrodinger Rutherford’s Gold Foil experiment Subatomic particles o Proton o Neutron o Electron Isotopes and mass number Average atomic mass Electron configuration o Energy level o Orbitals o Ground state vs. excited state Bright line spectra [email protected] Modeling using diagrams Mathematically manipulating equations Making predictions based on patterns Stating relationships Reference Tables || PERIODIC TABLE! Table S Table C (conversions) mslongshouseofscience.weebly.com OCTOBER: BLUE & ORANGE CLASSES SUNDAY 9 MONDAY 10 No School TUESDAY WEDNESDAY THURSDAY 13C FRIDAY 11 A 12 B 3.1 Atomic Theory Intro 3.2 Electrons and 3.3 Rutherford precision and the nucleus 3.4 Isotopes RA: 3.1 Regents RA: 3.2 Regents RA: 2.4 Regents RA: 3.3 Regents Chemistry work period 14 D SAT. 15 3.3 Rutherford simulation PS3 Due! 16 17 E 18 S 19 A 20 B 21 C 3.5 Average atomic mass 3.6 Bohr and energy levels 3.7 Ground vs. excited state 3.8 Bright line spectra 3.9 Schrodinger and a Mini-Quiz RA: 3.5 Regents RA: 3.6 Regents RA: 2.7 Regents RA: 3.8 Regents RA: 3.9 Regents 3.5 M&Mium mass lab 23 3.7 Flame test/spectra lab 24 D 25 E 26 S 3.10 Suborbital configuration 3.11 Element profile miniproject 3.12 Unit 3 Review RA: 3.10 Regents PS4 Due! 3.10 Periodic Table structure RA: 3.11 Regents 22 Chemistry work period 27 A Unit 3 Test 28 B 29 OCTOBER: RED CLASS SUNDAY 9 MONDAY 10 No School TUESDAY WEDNESDAY THURSDAY 11 A 12 B 13C 3.1 Atomic Theory Intro 3.2 Electrons and 3.3 Rutherford precision and the nucleus RA: 3.1 Regents RA: 3.2 Regents FRIDAY 14 D SAT. 15 3.4 Isotopes RA: 2.4 Regents Chemistry work period RA: 3.3 Regents 3.3 Rutherford simulation PS3 Due! 16 17 E 18 S 19 A 20 B 21 C 3.5 Average atomic mass 3.6 Bohr and energy levels 3.7 Ground vs. excited state 3.8 Bright line spectra 3.9 Schrodinger and a Mini-Quiz RA: 3.5 Regents RA: 3.6 Regents RA: 2.7 Regents RA: 3.8 Regents RA: 3.9 Regents 3.5 M&Mium mass lab 23 3.7 Flame test/spectra lab 24 D 25 E 26 S 3.10 Suborbital configuration 3.10 Periodic Table structure 3.12 Unit 3 Review RA: 3.10 Regents PS4 Due! RA: 3.10 Regents 3.11 Element profile miniproject 22 Chemistry work period 27 A Unit 3 Test Chemistry work period 28 B 29 UNIT Atomic Theory: Democritus and Dalton 3.1 What’s so special about atoms? Chemistry hasn’t been around forever, but postulations about how life and the universe work have. Hey, ladies. I’m Democritus. I like long walks on Greece’s beaches and philosophical arguments…in 400 B.C. I propose: Democritus was scientifically snubbed by philosophers of the day (you may be familiar with Plato and Aristotle). His ideas went disregarded for almost 1200 years, until John Dalton, an English scientist, decided to make a series of scientific claims based on experimental evidence surfacing about the structure and composition of matter: Just how small is an atom? Find an atom’s RADIUS on ___________________________: How big is that compared to a meter stick? Use _______________________________ to help: 3.1 Regents Practice 1. Locate the atomic radii of the following elements on Table S. Convert each radius into meters using Table C. Element Radius (pm) 2. Sample A contains molecules at STP. Radius (m) Br Explain, in terms of the composition, why sample A represents a pure substance. Na __________________________________________ __________________________________________ S __________________________________________ U 230 x 10-12 OR 2.30 x 10-10 __________________________________________ __________________________________________ __________________________________________ Use the information below to answer questions 3 and 4. 3. Classify potassium aluminum sulfate as an element, compound, or mixture. Justify your answer in terms of types of atoms and chemical bonds. _______________________________________________________________________________________________ _______________________________________________________________________________________________ 4. Can potassium aluminum sulfate be physically or chemically separated? Justify your answer in terms of types of matter. _______________________________________________________________________________________________ _______________________________________________________________________________________________ UNIT The Electron and Precision 3.2 How can we discuss super-precise, super-tiny measurements? Dalton’s ideas were far from perfect. However, they provided a basis for future experimentation to try and learn more about the stuff that makes up everything. J.J. Thomson was one such scientist who tried to add more detail to the model of the atom proposed by Dalton. Gas sample To explain his findings, Thomson upended one of Dalton’s claims. We CAN, in fact, break an atom down into smaller parts—subatomic particles called electrons. Subatomic particle: Electron: Those electrons must be embedded in some positively charged sphere (to keep things neutral), kind of like chocolate chips embedded within a plain cookie. HOLD UP: We’re getting to a point where we have to talk about precision in measurement. All this atomic stuff is on a SUPER tiny scale, so every number we can measure counts. Hence, here comes the concept of significant figures: Number of significant figures: Look for the first nonzero number! 23 0.145 0.0145 200 200. 50 times 0.103 42 times 0.023 3.2 Regents Practice Use the information below to respond to questions 1 through 3. 1. Identify the negatively charged particle Thomson discovered. _____________________________________________ 2. What does it mean to have “uniform density”? _______________________________________________________________________________________________ _______________________________________________________________________________________________ 3. What does it mean to be “electrically neutral”? _______________________________________________________________________________________________ _______________________________________________________________________________________________ Use your knowledge of significant figures to respond to questions 4 through 7. 4. The mass of an electron can be reported using a few different units/comparative values. Identify the number of significant figures in each measurement. a. 0.000548597 amu : _________________________ sig figs b. 9.109 x 10-31 kg (ignore the “x 10-31” in your count of sig figs): ___________________________________ sig figs c. 2.00 x 10-30 lbs (ignore the “x 10-30” in your count of sig figs): ____________________________________ sig figs d. 1840 times smaller than any other subatomic particle: ____________________________________ sig figs e. 1840. times smaller than any other subatomic particle ____________________________________ sig figs 5. Which mass measurement contains four significant figures? (1) 0.086 g (2) 0.431 g (3) 1003 g (4) 3870 g 6. The measurement 0.41006 g, rounded to three significant figures, is expressed as (1) 0.41 g (2) 0.410 g (3) 0.4100 g (4) 0.4101 g 7. A sample of a gas to be used in a cathode ray tube has a mass of 0.04161 grams and a volume of 3.8 cubic centimeters. To which number of significant figures should the calculated density of the sample be expressed? (1) 5 (2) 2 (3) 3 (4) 4 UNIT Rutherford and the Nucleus 3.3 How can we learn more about the structure of something we can’t even see? Thomson’s model opened doors for waves of scientists to see if there was more hidden inside the atom than just tiny electrons. Trouble is, when the atom is so small, it’s hard to see much. Ernest Rutherford came up with a way to indirectly “see” the inside of an atom: LET’S SHOOT STUFF AT A GOLD ATOM AND SEE WHAT HAPPENS! Rutherford’s ____________________ Experiment If Thomson is actually right, this experiment will be super boring. Why? Experimental Result (Observation) Explanation of Result (Conclusion) Dalton’s observations (and subsequent conclusions) led him to add more detail to the developing model of the atom: 3.3 Regents Practice 1. A student conducts a chemical reaction and observes the results. Which of the following statements contained in a student’s laboratory report is a conclusion? (1) A gas is evolved (created). (2) The gas is insoluble (does not dissolve) in water. (3) The gas is hydrogen. (4) The gas burns in air. 2. As a result of the gold foil experiment, it was concluded that an atom (1) Contains protons, neutrons, and electrons (2) Contains a small, dense, nucleus (3) Has positrons and orbitals (4) Is a hard, indivisible sphere 3. The gold foil experiment led to the conclusion that each atom in the foil was composed mostly of empty space because most alpha particles directed at the foil (1) Passed through the foil (2) Remained trapped in the foil (3) Were deflected by the nuclei in gold atoms (4) Were deflected by the electrons in gold atoms 4. An experiment in which alpha particles were used to bombard thin sheets of gold foil led to the conclusion that an atom is composed mostly of (1) Empty space and has a small, negatively charged nucleus (2) Empty space and has a small, positively charged nucleus (3) A large, dense, positively charged nucleus (4) A large, dense, negatively charged nucleus 5. State one conclusion about the internal structure of the atom that resulted from the gold foil experiment. _______________________________________________________________________________________ _______________________________________________________________________________________ 6. State one conclusion from Rutherford’s experiment that contradicts one conclusion made by Thomson. _______________________________________________________________________________________ _______________________________________________________________________________________ UNIT Isotopes and Mass Number 3.4 How can atoms of the same element be different? Rutherford’s new model of the atom (and the ensuing discovery of the neutron) shook up the way we think about what makes each element of the Periodic Table unique. We now know that each atom is made up of three different subatomic particles. Each of these subatomic particles contributes something unique to the atom. Subatomic Particle Charge Location Mass Electron Proton Neutron Nuclear charge: Net charge: What’s more, all this information gave us a way to start arranging and describing atoms on a nice, organized Table: 14 𝐶 6 Element symbol Fill in the missing element symbols and circle the two isotopes. 32 16 ____ 34 17 ____ In terms of subatomic particles, explain what makes the two species isotopes. 34 16 ____ 3.4 Regents Practice 1. The atomic number of an atom is always equal to the number of its (1) protons, only (2) neutrons, only (3) protons plus neutrons (4) protons plus electrons 7. Which subatomic particle will be attracted by a positively charged object? (1) proton (2) neutron (3) electron (4) positron 2. Which particles are found in the nucleus of an atom? (1) electrons, only (2) neutrons, only (3) protons and electrons (4) protons and neutrons 8. Which two particles have approximately the same mass? (1) proton and neutron (2) proton and electron (3) neutron and electron (4) neutron and an alpha particle 3. What is the total number of neutrons in an atom of an element that has a mass number of 19 and an atomic number of 9? (1) 9 (2) 10 (3) 19 (4) 28 9. Which statement about one atom of an element identifies the element? (1) The atom has 1 proton. (2) The atom has 2 neutrons. (3) The sum of the number of protons and neutrons in the atom is 3. (4) The difference between the number of neutrons and protons in the atom is 1 4. A neutral atom contains 12 neutrons and 11 electrons. The number of protons in this atom is (1) 1 (2) 11 (3) 12 (4) 23 5. Which statement is true about a proton and an electron? (1) They have the same masses and the same charges. (2) They have the same masses and different charges. (3) They have different masses and the same charges. (4) They have different masses and different charges. 6. Which statement concerning elements is true? (1) Different elements must have different numbers of isotopes. (2) Different elements must have different numbers of neutrons. (3) All atoms of a given element must have the same mass number. (4) All atoms of a given element must have the same atomic number. 10. What is the charge of the nucleus in an atom of oxygen-17? (1) 0 (2) -2 (3) +8 (4) +16 11. The nucleus of an atom of cobalt-58 contains (1) 27 protons and 31 neutrons (2) 27 protons and 32 neutrons (3) 59 protons and 60 neutrons (4) 60 protons and 60 neutrons 12. An atom of carbon-12 and an atom of carbon-14 differ in (1) Atomic number (2) Mass number (3) Nuclear charge (4) Number of electrons 13. Isotopes of an element must have different (1) Atomic numbers (2) Mass numbers (3) Numbers of protons (4) Numbers of electrons UNIT Average Atomic Mass 3.5 How can we discuss the mass of a large sample of atoms of an element? We’ve determined that the mass of an atom comes from its ___________________ and __________________ Check out the Periodic Table, though. What’s the deal with the decimal? We can’t have partial protons or neutrons! Average atomic mass: I’m an element sample that has 2% of my atoms with a mass of 14 (amu). All my other atoms weigh in at 12 amu. Can we just report my atomic mass on the Periodic Table as 13 amu and call it a day? Why or why not? Identify the most abundant isotope of fluorine. How do you know? Do all fluorine atoms have this mass? 3.5 Regents Practice 1. The atomic mass of an element is defined as the weighted average mass of that element’s (1) Most abundant isotope (3) Naturally occurring isotopes (2) Least abundant isotope (4) Natural and artificial isotopes 2. The atomic masses and the natural abundances of the two naturally occurring isotopes of lithium are shown in the table below. Which numerical setup can be used to determine the atomic mass of lithium? (1) (0.075)(6.02 u) + (0.925)(7.02 u) (2) (0.925)(6.02 u) + (0.075)(7.02 u) (3) (7.5)(6.02 u) + (92.5)(7.02 u) (4) (92.5)(6.02 u) + (7.5)(7.02 u) Hydrogen has three isotopes with mass number of 1, 2, and 3 and has an average atomic mass of 1.00794 amu. Use this information to answer questions 1 and 2. 3. This information about hydrogen indicates that (1) equal numbers of each isotope are present (2) more isotopes have an atomic mass of 2 or 3 than of 1 (3) more isotopes have an atomic mass of 1 than of 2 or 3 (4) isotopes have only an atomic mass of 1 4. To what number of significant figures is the average atomic mass of hydrogen expressed? (1) 1 (2) 3 (3) 5 (4) 6 The table below gives information about two isotopes of element X. 5. In terms of subatomic particles, state one difference between the two isotopes of element X. _______________________________________________________________________________________________ _______________________________________________________________________________________________ 6. Would you expect the atomic mass of element X to be closer to 10 amu or 11 amu? Explain your answer. _______________________________________________________________________________________________ _______________________________________________________________________________________________ 7. Calculate the average atomic mass of element X. A correct answer should include a numerical setup and a calculated result. UNIT Bohr Diagrams and Energy Levels 3.6 How did we first conceptualize the arrangement of electrons? Despite all the progress made in describing the structure of an atom, a good chemist is never satisfied. Niels Bohr was one of those unsatisfied chemists. What’s the deal with those electrons? Why so messy? Through a series of experiments that we’ll conceptually analyze in the next two lessons, Bohr was able to come to the conclusion that electrons are organized (configured) in energy levels (shells) that get progressively farther from the nucleus. Energy level (shell): Energy level 1 can hold up to _______ total electrons Energy level 2 can hold up to _______ total electrons Energy level 3 can hold up to _______ total electrons Energy level 4 can hold up to _______ total electrons Write the electron configuration and draw the Bohr diagram for boron. Indicate which electrons have the most energy. 3.6 Regents Practice 1. Compared to the energy and charge of the electrons in the first shell of a Be atom, the electrons in the second shell of this atom have (1) less energy and the same charge (2) less energy and a different charge (3) more energy and the same charge (4) more energy and a different charge 2. What is the total number of protons in an atom with the electron configuration 2-8-18-32-18-1? (1) 69 (2) 79 (3) 118 (4) 197 3. Which element has an atom with the electron configuration 2-8-8-2? (1) Mg (2) Ni (3) Ca (4) Ge 4. Which atom in the ground state has an outermost electron with the most energy? (1) Cs (2) K (3) Li (4) Na 5. How do the energy and location of an electron in the third shell of an atom compare to the energy and location of an electron in the first shell of the same atom? (1) In the third shell, an electron has more energy and is closer to the nucleus (2) In the third shell, an electron has more energy and is farther from the nucleus (3) In the third shell, an electron has less energy and is closer to the nucleus (4) In the third shell, an electron has less energy and is farther from the nucleus Use the information below to answer questions 6 through 8. 6. State the atomic number and the mass number of this element. Atomic number: _____________________________ Mass number: ________________________________ 7. State the number of electrons in each shell in this atom in the ground state. Number of e- in first shell: _____________________ Number of e- in second shell: ____________________ 8. State one way in which the Bohr model agrees with the Thomson model. _______________________________________________________________________________________________ _______________________________________________________________________________________________ UNIT Ground versus Excited State 3.7 How do electrons change when they’re hit with added energy? Bohr’s conclusions about the structure of the atom came from the analysis of hydrogen atoms (and a lot of ensuing math). He “hit” hydrogen atoms with a surge of energy and observed the resulting changes. Here’s the overview of what he concluded he’d seen: Step 1: Start with an atom in its “regular” state Step 2: Add energy to “excite” an electron to a higher energy state Step 3: Watch as electron releases energy in the form of light as it returns to its more stable “ground state” e- config: ________________ e- config: __________________ e- config: ____________________ ________________________ __________________________ ____________________________ Ground state: Excited state: 3.7 Regents Practice 1. Which electron configuration represents the electrons of an atom in an excited state? (1) 2-1 (2) 2-7-4 (3) 2-8-7 (4) 2-4 3. Which electron configuration represents the electrons of a sulfur atom in an excited state? (1) 2-6-6 (2) 2-7-7 (3) 2-8-4 (4) 2-8-6 2. What must occur when an electron in an atom returns from a higher energy state to a lower energy state? (1) A specific amount of energy is released (2) A random amount of energy is released (3) A specific amount of energy is absorbed (4) A random amount of energy is absorbed 4. During a flame test, a lithium salt produces a characteristic red flame. This red color is produced when electrons in excited lithium atoms (1) Are lost by the atoms (2) Are gained by the atoms (3) Return to lower energy states within the atoms (4) Move to higher energy states within the atoms An atom in an excited state has an electron configuration of 2-7-2. 5. Write the electron configuration of this atom in the ground state. _______________________________________ 6. Explain, in terms of subatomic particles, why this excited atom is electrically neutral. _______________________________________________________________________________________________ _______________________________________________________________________________________________ 7. Using the Bohr model, describe the changes in electron energy and electron location when an atom changes from ground state to excited state. _______________________________________________________________________________________________ _______________________________________________________________________________________________ _______________________________________________________________________________________________ An atom of fluorine-19 has an electron configuration of 2-6-1. 8. Explain why the number of electrons in the second and third shells show that this atom is in an excited state. _______________________________________________________________________________________________ _______________________________________________________________________________________________ _______________________________________________________________________________________________ 9. What is the total number of neutrons in this atom? ____________________________________________________ 10. Write an isotopic notation of this isotope of this element. Your response must include the atomic number, the mass number, and the symbol of this isotope. UNIT Bright Line Spectra 3.8 How can we use the behavior of electrons to design and discover? The structure of atoms of each element is consistent across the entire universe. Read that sentence again, because it’s kind of mind-boggling. Helium here on Earth is exactly the same as helium on the Sun, which, in turn, is exactly the same as helium from the most distant star we can detect. The elements are the common building blocks of the Universe. Each element also leaves a characteristic “fingerprint” that we can detect as an atom moves from excited state back down to ground state Bright-line spectrum: This “fingerprint” is more precise than the color seen on a flame test (just heating and observing), since a bright-line spectrum breaks down the visible light into its component wavelengths. Let’s take a look at what that means/looks like: In terms of electrons and energy states, explain how the lines in the bright-line spectra were generated. Which elements make up the mixture? How can you tell? 3.8 Regents Practice 1. A specific amount of energy is emitted when excited electrons in an atom in a sample of an element return to the ground state. This emitted energy can be used to determine the (1) Mass of the sample (2) Volume of the sample (3) Identity of the element (4) Number of particles of the element 2. The bright-line spectrum of sodium is produced when energy is (1) Absorbed as electrons move from higher to lower electron shells (2) Absorbed as electrons move from lower to higher electron shells (3) Released as electrons move from higher to lower electron shells (4) Released as electrons move from lower to higher electron shells 3. The diagram below represents the bright-line spectra of four elements and a bright-line spectrum produced by a mixture of three of these elements. Which element is not present in the mixture? (1) A (3) X (2) D (4) Z Fireworks that contain metallic salts such as sodium, strontium, and barium can generate bright colors. A technician investigates what colors are produced by the metallic salts by performing flame tests. During a flame test, a metallic salt is heated in the flame of a gas burner. Each metallic salt emits a characteristic colored light in the flame. 4. State how bright-line spectra viewed through a spectroscope can be used to identify the metal ions in the salts used in the flame tests. _______________________________________________________________________________________________ _______________________________________________________________________________________________ _______________________________________________________________________________________________ 5. Explain, in terms of electrons, how a strontium salt emits colored light. _______________________________________________________________________________________________ _______________________________________________________________________________________________ _______________________________________________________________________________________________ 6. Explain why the electron configuration of 2-7-1-1 represents a sodium atom in an excited state. _______________________________________________________________________________________________ _______________________________________________________________________________________________ UNIT Schrodinger and the Orbital 3.9 How did modern physics upend the model of the atom? Bohr’s atomic model is so neat, tidy, and precise. Heck, the Regents chemistry curriculum likes the Bohr model so much it’s almost all they use. Unfortunately, life ain’t neat, tidy, or precise. Erwin Schrodinger gets that. That’s why he came through with some quantum physics to rock your world and, once more, transform our thinking about atomic structure. Oh you need me? I’ll be right over here…probably. Schrodinger maintained that electrons were still organized by their energies; however, he recognized that we can’t know exactly where they are. We can just give our best guess. Orbital: There will be a multiple-choice question on Part A of the Regents exam in June asking you about what an orbital is. Be ready for it. 3.9 Regents Practice 1. According to the wave-mechanical model, an orbital is defined as the (1) Circular path for electrons (2) Circular path for protons (3) Most probable location of electrons (4) Most probable location of protons 2. An orbital of an atom is defined as the most probable location of (1) An electron (2) A neutron (3) A positron (4) A proton 3. The modern model of the atom show that electrons are (1) Orbiting the nucleus in fixed paths (2) Found in regions called orbitals (3) Combined with neutrons in the nucleus (5) Located in a solid sphere covering the nucleus 4. Which phrase describes an atom? (1) A positively charged electron cloud surrounding a positively charged nucleus (2) A positively charged electron cloud surrounding a negatively charged nucleus (3) A negatively charged electron cloud surrounding a positively charged nucleus (4) A negatively charged electron cloud surrounding a negatively charged nucleus 5. Which group of atomic models is listed in historical order from the earliest to the most recent? (1) Hard-sphere model, wave-mechanical model, electron-shell model (2) Hard-sphere model, electron-shell model, wave-mechanical model (3) Wave-mechanical model, electron-shell model, hard-sphere model (4) Electron-shell model, wave-mechanical model, hard-sphere model Unit 3 Review Questions 6. Compared to the charge of a proton, the charge of an electron has (1) A greater magnitude and the same sign (2) A greater magnitude and the opposite sign (3) The same magnitude and the same sign (4) The same magnitude and the opposite sign 7. Which notation represents an atom of sodium with an atomic number of 11 and a mass number of 24? (1) 24 11𝑁𝑎 (2) 11 24𝑁𝑎 (3) 13 11𝑁𝑎 (4) 35 11𝑁𝑎 8. Which statement concerning elements is true? (1) Different elements must have different numbers of isotopes. (2) Different elements must have different numbers of neutrons. (3) All atoms of a given element must have the same mass number. (4) All atoms of a given element must have the same atomic number. UNIT 3.10 9. Elements on the modern Periodic Table are arranged in order of increasing (1) Atomic mass (2) Atomic number (3) Number of neutrons (4) Number of outermost electrons 10. Each diagram below represents the nucleus of a different atom. Which diagrams represent nuclei of the same element? (1) D and E, only (2) D, E, and Q (3) Q and R, only (4) Q, R, and E Suborbitals, Electron Configuration, and the Periodic Table How can the arrangement of electrons provide insight to the arrangement of the PT? In order to better understand why the Periodic Table and its elements look the way they do, we’re going to dig a bit deeper into Schrodinger’s model. These ideas are at the heart of advanced chemistry and explain near EVERYTHING. Schrodinger tells us that each of Bohr’s energy levels actually contains a specific number of “sublevels.” Currently, we have only observed 4 types of sublevels, abbreviated with letters: s, p, d, and f. Each sublevel has a different size/shape and fits a different number of orbitals. Each orbital can hold up to 2 electrons. It’s kind of like a weird hotel. The energy level tells you what floor you’re on. The sublevel tells you which wing—each wing has a different number of available rooms (orbitals). Each room can hold 2 occupants (electrons). Sublevel (“wing”) s p d f # of Orbitals (“rooms”) 1 3 5 7 Max # of electrons (“occupants”) 2 6 10 14 Have you ever wondered why the Periodic Table looks like a weird castle-like thing? Check out the size of the “blocks” that make up the different sections of the Periodic Table: 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 7s 7p (no more level-6 sublevels have been observed yet) (no more level-7 sublevels have been observed yet) Let’s “translate” electron configurations from your Reference Table into richer Schrodinger-based configurations. Element Bohr e- Configuration Schrodinger e- Configuration He (helium) Be (beryllium) F (fluorine) K (potassium) Fe (iron) Kr (krypton) Which sublevels do the maximum 8 total electrons of energy level 2 come from? _____________ and ______________ Which sublevels do the maximum 18 total electrons of energy level 3 come from? ________, ________, and ________ The concept of energy levels is stressed in Regents Chemistry; however, the concept of sublevels provides a more powerful and accurate understanding of the Periodic Table and the behavior of its elements. 3.10 Regents Practice 1. Compared to the maximum number of electrons that can occupy the d sublevel, the maximum number of electrons that can occupy the p sublevel (1) Is smaller by 2 electrons (2) Is smaller by 4 electrons (3) Is greater by 2 electrons (4) Is greater by 4 electrons 4. Which sublevels are occupied in the outermost energy level of an argon atom in the ground state? (1) 3s and 3d (2) 3s and 3p (3) 2s and 3p (4) 2p and 3d 2. The total number of orbitals in the d sublevel is (1) 1 (2) 3 (3) 5 (4) 7 5. Which of the following elements has all of its sublevels completely filled? (1) Li (2) B (3) N (4) Ne 3. Which element has atoms in the ground state with a sublevel that is only half-filled? (1) Helium (2) Beryllium (3) Nitrogen (4) Neon 6. What is the total number of occupied sublevels in an atom of chlorine in the ground state? (1) 1 (2) 3 (3) 5 (4) 9 7. Write the electron configuration, using Bohr AND sublevel notation, for the following elements Element Bohr e- Configuration Schrodinger e- Configuration N (nitrogen) Mg (magnesium) As (astatine) Al (aluminum) Tc (technetium) 8. Compare the properties of the model of the atom proposed by Thomson with those of the wave-mechanical model of the atom as described by Schrodinger. Regents Practice Answer Key 3.1 3.3 1. Element Br Radius (pm) 117 Na 160. S 104 U 230. Radius (m) 117 x 10-12 OR 1.17 x 10-10 160 x 10-12 OR 1.60 x 10-10 104 x 10-12 OR 1.04 x 10-10 230 x 10-12 OR 2.30 x 10-10 2. All particles are the same; Sample A has only one type of molecule (made by chemically bonding 2 different atoms); Sample A is not a mixture 3. Potassium aluminum sulfate is a compound because it is composed of more than one type of atom chemically bonded in a fixed proportion. 4. Potassium aluminum sulfate can be chemically, not physically, separated because it is a compound (meaning it has different types of atoms connected by chemical bonds that could be broken). 3.2 1. Electron 2. Mass is spread equally over the entire volume— no areas are packed/condensed more tightly than others 3. The amount of positive and negative charge is equal (“cancels out”) 4. a. 6 b. 4 c. 3 d. 3 e. 4 5. 3 6. 2 7. 2 (limited by the 2 sig figs of the volume…the “weakest link”) 1. 2. 3. 4. 5. 3 2 1 2 The atom is made mainly of empty space OR The atom contains a small, dense positively charged center (nucleus) 6. Positive charge is concentrated in the nucleus, not uniformly throughout the atom OR The atom is mostly empty space, not uniform positive charge 3.4 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 1 4 2 2 4 4 3 1 1 3 1 2 2 3.5 1. 2. 3. 4. 5. 3 1 3 4 The two isotopes of element X have a different number of neutrons 6. The atomic mass of element X should be closer to 11 amu because the isotope with a mass of 11 is more abundant than the isotope with a mass of 10. 19.91 7. 𝐴𝑡𝑜𝑚𝑖𝑐 𝑚𝑎𝑠𝑠 = ( 100 ) (10.01) + 80.09 ( )(11.01) 100 𝐴𝑡𝑜𝑚𝑖𝑐 𝑚𝑎𝑠𝑠 = (0.1991)(10.01) + (0.8009)(11.01) 𝐴𝑡𝑜𝑚𝑖𝑐 𝑚𝑎𝑠𝑠 = 1.992991 + 8.817909 Atomic mass = 10.81 (4 sig figs in problem) 3.6 3.8 1. 2. 3. 4. 5. 6. 3 2 3 1 2 Atomic number: 4 Mass number: 9 7. First shell: 2 Second shell: 2 8. Both models include electrons; both models are electrically neutral 3.7 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 2 1 2 3 2-8-1 The atom has the same number of negatively charged electrons as it does positively charged protons. When an atom changes from ground state to excited state, one of its electrons absorbs a specific amount of energy and moves from a lower energy level/shell to a higher energy level/shell. One electron has moved into the third shell before the lower-energy second shell was full. 10 19 9𝐹 1. 2. 3. 4. 3 3 3 The bright-line spectra “fingerprint” seen through a spectroscope can be compared to the known spectra “fingerprints” of metal ions. Shared spectral lines show that a metal ion must be present in the tested salt. 5. A strontium salt absorbs a specific amount of energy, changing one of its electrons from its ground state to a higher-level excited state. The atom emits colored light when an excited electron releases energy when returning back to its ground state from a higher energy level/shell. 6. The ground state of a sodium atom is 2-8-1. The second shell is no longer full; an electron has been excited to a higher energy level. 3.9 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 3 1 2 3 2 4 1 4 2 2 3.10 1. 2. 3. 4. 5. 6. 7. 2 3 3 2 4 3 (1s, 2s, 2p, 3s, and 3p are occupied) Bohr e- Configuration Element Schrodinger e- Configuration N (nitrogen) 2-5 1s22s22p3 Mg (magnesium) 2-8-2 1s22s22p63s2 As (astatine) 2-8-18-5 1s22s22p63s23p64s23d104p3 Al (aluminum) 2-8-3 1s22s22p63s23p1 Tc (technetium) 2-8-18-13-2 1s22s22p63s23p64s23d104p65s24d5 8. While Thomson suggested that electrons were embedded in a uniform sphere of positive charge, Schrodinger’s wave-mechanical model describes electrons as being most likely to exist in orbitals that surround the nucleus—a positively charged, dense center of the atom.