Honors Chemistry: Atomic Theory/Nuclear Test Review Particles of the Atom proton, neutron, electron…nucleons? charges, location, masses mass number, atomic number charged atoms = ions Isotopes same element (protons), different masses (neutrons) Complete Atomic Designation Average Atomic Mass radioactive isotopes o half-Life nuclear transmutation reactions o decay particles: alpha, beta, gamma, positron o emission/decay v. bombardment fission v. fusion E = mc2 History of the Atom (what resulted from each model?) Greeks John Dalton o Atomic Theory (know postulates) J.J. Thomson o cathode ray tube o plum-pudding model Rutherford o gold foil experiment Chadwick o discovered neturons Bohr o planetary model of the atom Name_______KEY_______________ Light Quantum Mechanical Model o electron cloud model o orbitals ground state v. excited state o absorption of energy light emission (emission spectrum) characteristics of waves o wavelength, frequency, crest, trough, amplitude o How does wavelength change v. frequency? v. energy? …frequency v. energy? calculations o c = λf, where c = 3.0 x 108 m/s o E = hf, where h = 6.63 x 10-34 J s Electron Configuration energy levels, types of orbitals, filling order (use Periodic Table) shorthand notation (using noble gases) orbital diagrams (filling order) o aufbau Principle o Hund’s Rule o Pauli Exclusion Principle valence electrons vs. kernel (core) electrons ion formation (losing/gaining e-) and octet rule Periodic Table s-block, p-block, d-block, f-block charges (+1, +2,…..2-, 1-) Atomic Structure Review Questions 1. Using your vocabulary and your notes, fill in the following blanks. Protons are POSITIVELY charged particles in the NUCLEUS of an atom. The protons have a mass of approximately ONE AMU. The number of protons in the nucleus, also called the ATOMIC NUMBER, is responsible for determining the type of atom, or the ELEMENT. The NEUTRONS are also in the nucleus with the protons, together their sum is the MASS NUMBER. Neutrons are almost equal in mass to the protons and are NEUTRAL in charge. NEUTERONS are responsible for creating isotopes. Outside the nucleus are the ELECTRONS which can be gained or lost to produce IONS. Positively charged ion are called CATIONS, while negatively charged ions are called ANIONS. 2. Using your vocabulary and your notes, complete the following table. Scientist Dalton Experiment/Observation Law of multiple proportions, atoms are indivisible, all atoms of an element are the same Discovery or Major Contribution Atomic Theory Model Cathode ray tube Electrons and + charges (plum-pudding model) Gold-Foil Experiment + Nucleus; Atom is mostly empty space. Electrons have only specific energy levels and distances from the nucleus that are allowed. Electrons in ORBIT at fixed distances from nucleus (planetary model) Math / probability s-, p-, d-, f-orbitals Quantum Mechanical Model Thomson Rutherford Bohr Various 3. The element Chemistrium (Ch) has 2 varieties, Ch-110 and Ch-112. Ch-110 has a % abundance of 73%. Find the average atomic mass of Ch. AAM = (% A)(mass A) + (% B)(mass B) AAM = (0.73)(110 amu) + (0.27)(112 amu) AAM = 80.3 amu + 30.24 amu AAM = 110.54 amu 4. The element rubidium (Rb) has an average atomic mass of 85.468 amu. Rubidium has two common isotopes, 85Rb and 87Rb. The average atomic mass of 85Rb is 85.00 amu and the abundance of is 72.2%, what is the average atomic mass of 87Rb? AAM = (% A)(mass A) + (% B)(mass B) 85.468 amu = (0.722)(85.00 amu) + (0.278)(x amu) 24.098 = 0.278 x x = 86.68 amu = 87Rb 5. Complete the following table: Atomic # Protons Neutrons Electrons Mass # Net Charge 23 23 28 18 51 5+ Complete Atomic Designation 51 V 5+ 23 209 83 83 126 80 209 3+ 83 178 72 72 106 68 178 4+ Bi 3+ Hf 4+ 72 6. Complete the chart below concerning the different types of radioactive decay: alpha composition helium nucleus beta fast-moving electron gamma positron high-energy wave + charged e- 0 symbol charge 2+ high 1~0 amu (0.00054 amu) low medium-low 1+ ~0 amu (0.00054 amu) low approx. mass ~ 4 amu approx. energy penetrating power low moderate very high moderate 0 amu 7. Complete the following transmutation reactions: e. Americium-240 decays by alpha emission and a. Radon-225 decays by beta emission: 225 86 Rn 0 1 e 225 87 then beta emission: 240 95 Fr b. Samarium-147 decays by alpha emission: 147 62 c. Sm 4 2 He 143 60 f. Tm 10 e 186 68 Al 0 1 e 25 12 He 0 1 e 236 94 Pu An alpha particle bombards an phosphorus-32 32 15 P 4 2 He 1 0 n 35 17 Cl g. An alpha particle bombards a fluorine-19 atom, Er producing a new atom and a proton: d. Aluminum-25 undergoes positron emission: 25 13 4 2 atom, producing a new atom and a neutron: Nd Thulium-186 undergoes electron capture: 186 69 Am 19 9 Mg F 4 2 He 1 1 p 22 10 Ne 8. What is the definition of half-life? The time it takes for half of a radioactive element to decay 9. The half-life of a substance is 9.7 ms. How long will it take for 25 % of the original amount to remain? 100% 50% 25% = 2 half-lives 9.7 ms x 2 half-lives = 19.4 ms 19 ms 10. If you originally had 100. g of a substance, how much will you have left after 4 half-lives? After 5 half-lives? 100. g 50.0 g 25.0 g 12.5 g 6.25 g 3.13 g 11. A given substance has a half-life of 2.0 x 109 years. If you buy 150. g of this substance, how much will be left after 12,000,000,000 years? 12 x 109 yr / 2.0 x 109 yr = 6 t1/2 150 (1/2)6 = 2.3438 2.34 g 12. What is the half-life of a substance, if after 5000 years, a 1800 g sample now masses 450 g? 1800 g 900 g 450 g = 2 t1/2 5000 yr / 2 = 2500 yr for every t1/2 13. The mass of a thorium-232 nuclide is 232.011 amu. What is the mass defect (in amu)? 90 p (1.00728 amu) 142 n0 (1.00866 amu) 233.88492 amu mass defect 233.88492 amu 232.011 amu 1.87392 amu 14. Calculate the energy produced by the thorium-232 nuclide (in J). 1 kg 1g 1.87392 amu 23 6 . 02 x 10 amu 1000 g 3.11282 x 1027 kg 2 E mc 3.11282 x 10 2 27 m kg 3 x 108 s 2.80154 x 10 10 J 15. Draw two light waves: one with a long wavelength and one with a short wavelength. Wavelength is inversely related to frequency and energy. So, a wave with a long wavelength would have both a lower frequency and a lower energy. The wave with a short wavelength would have a comparably larger frequency and energy. Remember that frequency and energy are directly related. Compare the frequency and energy of your two waves. 16. The following diagrams show energy changes within an atom as an electron either absorbs or emits energy. a. Which diagram shows energy being absorbed? Diagram I: energy is absorbed, causing an e- to be promoted from level 2 to level 5 (excited) …emitted as light (given off)? b. e- e- Diagram II: light is emitted as the e- falls from level 4 back down to level 2 I. c. II. Which diagrams shows the greatest change in energy? Diagram I: the difference in energy from levels 2 to 5 is greater than from levels 4 to 2. d. Assuming light is involved in both energy changes, which diagram illustrates light with a longer wavelength? Why? Diagram II: wavelength is inversely related to energy, so because this diagram has the smaller energy change, its resulting wave will have a longer wavelength 17. A photon of light has a wavelength of 3.20 x 103 cm. Find… λ = 3.20 x 101 or 32 m (must use m for these eq.) a. the frequency of the radiation. c = λ· f b. the energy of the photon. E = h·f 8 3.0 x 10 m/s = 32 m (f) E = 6.63 x 10-34 J·s (9,375,000 Hz) f = 9.4 x 106 Hz E = 6.2 x 10-27 J 18. Write the longhand and shorthand electron configurations for the following atoms: valence e- in red Longhand Shorthand a) boron B = 1s22s22p1 B = [He] 2s22p1 b) nitrogen N = 1s22s22p3 N = [He] 2s22p3 c) cadmium Cd = 1s22s22p63s23p64s23d104p65s24d10 Cd = [Kr] 5s24d10 d) sodium ion Na+ = 1s22s22p6 Na+ = [He] 2s22p6 or [Ne] e) phosphide ion P3- = 1s22s22p63s23p6 P3- = [Ne] 3s23p6 or [Ar] 19. For 18a and 18b, draw an orbital diagram below. You can use boxes for the orbitals and arrows for the electrons. 18a. 18b. 20. Look at your periodic table. For each of the following elements, answer the following: a. How many valence electrons does this element have? b. …core electrons? c. How many electrons would this element gain or lose to become more stable? Specify gain or lose. d. What charge would this element have after following the octet rule? H N O Br Mg Kr a. 1 5 6 7 2 8 b. 0 2 2 28 10 c. loses 1e- gains 3 e- gains 2 e- gains 1 e- loses 1e- d. 1+ 3- 2- 1- 2+ 28 neither gains nor loses 0