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Atomic Theory Unit 1 Mr. Marash At the conclusion of the Unit you will be able to: Use models to describe the structure of the atom Describe scientific experiments and explain how they relate to the structure of an atom Determine the number of protons, neutrons and electrons in an atom or an ion given its mass number Calculate the mass number given protons and neutrons Calculate the atomic mass given relative abundance Determine the most abundant isotope given atomic mass Distinguish between ground state and excited state based on electron configuration Identify an element by comparing bright line spectra to a given spectra Determine the number of valence and non-valence electrons of an atom given its electron configurations Draw Lewis Dot (electron dot) diagrams of atoms and ions Interpret and write isotopic notation Compare and contrast the subatomic particles in terms of charge, mass and location in the atom Distinguish between chemicals changes and physical changes Frame of Reference Activity Example: Chemistry> Directions: 1. Use the word Chemistry to generate at least 4 words or phrases that relate to Chemistry and write them in the circles. It can be anything you know 2. Then in the squares write down how you know that word or phrase. Daily Essential Question:____________________________________________________________________ Daily Essential Question:____________________________________________________________________ What Makes up an atom?? Read Pages 113-114, starting with “The proton and the neutron” and answer the following questions 1. Compare and contrast a proton and a neutron, in terms of charge and mass (mention both charge and mass in your answer). ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ 2. Compared to a proton, an electron has a) the same charge and mass b) the opposite charge and the same mass c) the opposite charge and less mass d) the opposite charge and greater mass 3. Which statement best describes the nucleus? a) it contains most of the mass of the atom and occupies the most volume of the atom b) it contains most of the mass of the atom, but occupies a small percentage of the volume of the atom c) it contains a small percentage of the mass of the atom and occupies a small percentage of the volume of the atom d) it contains a small percentage of the mass of an atom, but occupies the most volume of the atom. Cite evidence from the text to support your answer for #3. 4. ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ 5. Draw a model (diagram) of the atom. Label nucleus, proton, neutron, and electron cloud 6. What did you learn from this reading that you did not know before? Daily Essential Question:____________________________________________________________________ What Makes up an atom?? I. Structure of an Atom A. What is an Atom i. ii. iii. B. Subatomic Particles (Table O in reference Table) Particle Proton Neutron Electron Symbol Charge Mass Location Daily Essential Question:____________________________________________________________________ As time elapsed, how did the model of the atom evolve? II. The History of Atomic Theory The word atom comes from the Latin words ATOMOS (TRANSLATION ___________________________________________________________________) A. Dalton-1803 (Reference: Textbook p. 104-105) 1. Experimental Evidence Law of Conservation of Mass Law of Definite Properties Law of Multiple Proportions 2. What were the conclusions of Dalton’s Experiments? 3. What is Dalton’s Model of the Atom? a. b. c. 4. Picture of Dalton’s Model Solid Sphere (Kinda like a marble) Daily Essential Question:____________________________________________________________________ As time elapsed, how did the model of the atom evolve? B. J.J. Thomspon- 1897 (Textbook p. 107-110) 1. Cathode Ray Experiment 2. Experimental evidence a b 3. What were the conclusions of Thompson’s Experiment? a. b. 4. The PLUM PUDDING MODEL (or Yogurt and Granola) a. b. 5. Picture of Thompson’s Model Daily Essential Question:____________________________________________________________________ As time elapsed, how did the model of the atom evolve? C. Ernest Rutherford – 1909 (Textbook p. 111-113) 1. The Gold Foil Experiment- Rutherford shot alpha particles, which are positively (+) charged, at a sheet of gold foil. 2. Experimental Evidence a b 3. If you shot positive particles at atoms and only some were deflected what conclusion would you make? Make your prediction below. (Hint: Opposites attract) 4. What did Rutherford’s model look like? a. b. c. 5. Draw the Rutherford model As time elapsed, how did the model of the atom evolve? Daily Essential Question:____________________________________________________________________ D. Niels Bohr – 1913 (Textbook p. 146-148) 1. Analyzed _____________________________ of hydrogen a. Emission Spectra is _____________________________________________ 2. Experiment Evidence 3. How could this happen? (Conclusions) a. b. 4. What did Bohr’s model look like? a. b. c. 5. Picture of The Bohr Model 6. Practice Regents Questions Daily Essential Question:____________________________________________________________________ 1. Which of the following did Rutherford’s Gold Foil experiment prove? 4. According to the Wave-Mechanical Model, a. That the atom was a uniformly dense sphere. a. electrons are found in areas of high probability called orbitals b. That the atom is mostly empty space with a dense, positive core. b. electrons travel around the nucleus in circular paths called orbits c. That most the atom consists of a uniform positive “pudding” with small negative particles called electrons embedded throughout. c. electrons are found in areas of high probability called orbits d. That electrons travel around the nucleus in well-defined paths called orbits. 2. J.J. Thomson’s Cathode Ray Tube experiment led to the discovery of a. the positively charged subatomic particle called the electron b. the positively charged subatomic particle called the proton c. the positively charged subatomic particle called the electron d. the negatively charged subatomic particle called the electron d. electrons travel around the nucleus in random paths called orbitals 5. Which of the following does not follow Dalton’s Postulates? a. All atoms of a given element are identical b. All atoms look like a simple sphere c. Compounds are formed by combinations of 2 or more different elements d. Atoms of different elements have different properties and masses 6. When electrons in an atom gain or absorb enough energy, they can a. jump to the ground state 3. According to the Bohr Model, a. electrons are found in areas of high probability called orbitals b. electrons travel around the nucleus in circular paths called orbits c. electrons are found in areas of high probability called orbits d. electrons travel around the nucleus in random paths called orbitals b. fall back to the ground state c. jump to an excited state d. fall back to an excited state 7. When excited electrons lose or emit enough energy, they can a. jump to the ground state b. fall back to the ground state c. jump to an excited state d. fall back to an excited state How do I Differentiate Between Atoms? Daily Essential Question:____________________________________________________________________ III. Atomic Number and Mass Number a. Atomic Number X QUESTION: How many protons are in the following atoms? Oxygen (O) Cholrine (Cl) Calcium (Ca) Mercury (Hg) QUESTION: Which element has: 15 protons 25 protons 38 protons 82 protons b. Mass Number X How do I Differentiate Between Atoms? Reminder to yourself: How do you figure this out? Daily Essential Question:____________________________________________________________________ QUESTION: How many protons, neutrons and electrons are in the following? 55Fe Element Sodium-23 P-31 *** Take note of the different notations used to represent an element*** Proton Count Neutron Count Electron Count Putting it all together For the following symbols, identify the number of p,n,e, atomic number, mass number and element symbol. Symbol Protons Neutrons Electrons Atomic # Mass # Element 7 3𝑋 2 1𝑋 79 32𝑋 Different Forms of Elements Daily Essential Question:____________________________________________________________________ IV. Isotopes Example Element 12C Proton Count 13C 14C What two things stay the same for isotopes? Neutron Count Electron Count V. Atomic Mass A. B. QUESTIONS: 1. If there exists 25% of Cl-37 and 75% of Cl-35 what is the atomic mass of chlorine? 2. Copper has two isotopes, Cu-63 and Cu-65. There is 69.2% copper-63 and 30.8% copper 65. What is the atomic mass of copper? Different Forms of Elements Daily Essential Question:____________________________________________________________________ 3. Atomic mass can also be identified as the MOST ABUNDANT isotope. a. Which isotope is more abundant Na-22 or Na-23? b. Hydrogen has three isotopes, H-1, H-2 and H-3. Which one is most abundant? VI. Ions 1. A. B. C. 2. QUESTIONS: Fill in the table below Daily Essential Question:____________________________________________________________________ Element Protons Electrons Na+ ClMg2+ S2Write the symbols for an ion with 9p and 10 e _______________________ 13p and 10 e_____________________ 24p and 21 e______________________ 7p and 10 e_______________________ What is the charge on a magnesium ion that has lost two electrons? _______ What is the charge on a fluoride ion that has gained one electron? _______ Give the correct chemical symbol for the ion formed when oxygen gains 2 electrons: _______ Give the correct chemical symbol for the ion formed when sodium loses one electron: _______ Back to the Bohr-Ring Model Daily Essential Question:____________________________________________________________________ Warm-up: How did Bohr improve upon Rutherford’s Atomic model? Look back in your notes if you need to. VII. Energy Levels A. B. Energy Level (n) n= Number of electrons 1 n= n= n= C. n= D. What Happens when Electrons Change Energy Levels? Daily Essential Question:____________________________________________________________________ VIII. Electron configuration A. Ground State of atomsExamples: B. Ground State of ions- Na Ge Au Ar O Fe Examples: C. Na+ Cl- Se2- Sr2+ Rb+ O2D. How can you tell the if the electron configuration is for ground state or excited state? Questions: 2-1:_____________________ 2-8-2:___________________ 2-0-1:___________________ 2-8-8-2:_________________ 2-7-3:___________________ 2-8-17-6:________________ IX. Bohr Models- Daily Essential Question:____________________________________________________________________ C. Bohr Diagrams – 1. Look up electron configuration of element (if you are working with an ion, add/subtract the proper amount of electrons from outer shell of configuration) 2. Draw nucleus (with a square) and write correct number of protons and neutrons inside. 3. Using rings or shells, place the proper number of orbits around your nucleus. 4. Using either an “x” or a dot to represent your electrons, place the correct number of electrons in the area that would correspond to the number 12 on the face of a clock in the orbit closest to the nucleus only. 5. Place one “x” or one dot at a time around your 2nd orbit in the areas that would correspond to the numbers 12, 3, 6, and 9 on the face of a clock. 6. If there are any electrons remaining in your configuration, pair them up with electrons you have already placed. Questions/Practice: Carbon e- configuration_____________ F- e- configuration____________ Daily Essential Question:____________________________________________________________________ Na+ e- configuration_____________ Ar e- configuration_____________ Al e- configuration_____________ S2- e- configuration______________ X. Lewis Dot Diagrams Daily Essential Question:____________________________________________________________________ A. Valance Electrons- Examples: Mg ________________ C__________________ B. Lewis Dot Diagrams- Steps to Draw a Lewis Dot Diagram 1. Write the element’s symbol 2. Retrieve electron configuration from Periodic Table. The last number in the configuration is the___________________________ 3. Using either an “x” or a dot to represent your electrons, place that many electrons in the next orbit in the areas that would correspond to the numbers 12, 3, 6, and 9 on the face of a clock. 4.If you are working with an ION you must adjust the valence electrons (add or subtract electrons) in the configuration before constructing your Dot Diagram. Your final diagram must include brackets and the charge on the ion. Practice: Daily Essential Question:____________________________________________________________________ Argon Nitrogen N3- Oxygen Silicon Sodium Na+1 O2- 1. What is the advantage to using the Bohr model as opposed to the Lewis model? a. The Bohr model provides more information than the Lewis model. b. The Bohr model is less bulky than the Lewis model. c. The Bohr model shows the valence electrons. d. The Bohr model shows how many bonds atoms of an element can form. 2. What is the advantage to using the Lewis model as opposed to the Bohr model? a. The Lewis model provides more information than the Bohr model. b. The Lewis model is less bulky than the Bohr model. c. The Lewis model shows the valence electrons. d. The Lewis model shows how many bonds atoms of an element can form. 3. What is the maximum number of electrons an atom or an ion can have in its valence shell? a. 2 c. 6 b. 4 4. 8 XI. Physical and Chemical Changes Daily Essential Question:____________________________________________________________________ A. Physical and Chemical Properties 1. Physical properties — a. Intensive property Examples: b. Extensive property – Examples: 2. Chemical properties — Examples: B. Physical and Chemical Changes 1. Physical change – Examples: 2. Chemical change – Daily Essential Question:____________________________________________________________________ Example: 3. Four signs of a possible chemical change a. b. c. d. A precipitate is Daily Essential Question:____________________________________________________________________ Vocab review: Atomic mass Atomic mass unit Atomic Number Atomic Radius Bohr’s model Bright-line/ Emission Spectra Cathode ray Chemical Change Chemical Property Dalton’s Model Electron Electron Configuration Energy level Excited state Gold foil Experiment Ground state Ion Isotope Lewis dot Diagram Mass number Neutron Daily Essential Question:____________________________________________________________________ Nucleus Nucleon Orbital Physical Change Physical Property Proton Rutherford’s Model Subatomic Particles Thomson’s Model Valence Electron WaveMechanical Model