Atomos, Teorías Atómicas, Teoría Cuántica, Masa Atómica e Isotopos

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Atomos, Teorías Atómicas, Teoría Cuántica, Masa Atómica e Isotopos

  1. 1. Chapter 4 Atoms and Elements 4.3 Atom- smallest particle of The Atom an element that retains the characteristics of that element Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings 1
  2. 2. Chapter 4 Atoms and Elements 4.1 Elements and Symbols Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings 2
  3. 3. Elements Elements are • Pure substances that cannot be separated into simpler substances by ordinary laboratory processes. gold carbon aluminum Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings 3
  4. 4. Sources of Some Element Names Some elements are Table 4.1 named for • planets, • mythological figures, • minerals, • colors, • scientists, and • places. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings 4
  5. 5. Symbols of Elements A symbol • Represents the name of an element. • Starts with a capital letter. Examples: C carbon Co cobalt N nitrogen Ca calcium F fluorine Al aluminum O oxygen Mg magnesium 5
  6. 6. Learning Check Select the correct symbol for each: A. calcium 1) C 2) Ca 3) CA B. sulfur 1) S 2) Sl 3) Su C. iron 1) Ir 2) FE 3) Fe 7
  7. 7. Solution Select the correct symbol for each: A. calcium 2) Ca B. sulfur 1) S C. iron 3) Fe 8
  8. 8. Learning Check Select the correct name for each symbol: A. N 1) neon 2) nitrogen 3) nickel B. P 1) potassium 2) phosphorus 3) phlogiston C. Ag 1) silver 2) agean 3) gold 9
  9. 9. Solution Select the correct name for each: A. N 2) nitrogen B. P 2) phosphorus C. Ag 1) silver 10
  10. 10. Subatomic Particles Atoms contains subatomic particles • Protons positive (+) charge. • Neutrons are neutral. • Electrons negative (-) charge. ( very small mass) Like charges repel and unlike charges attract. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings 14
  11. 11. Structure of the Atom An atom consists • nucleus (protons and neutrons) • large empty space around the nucleus (electrons) Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings 15
  12. 12. Particles in the Atom Table .5 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings From page 107 do exercises 4.15 to 4.22 (don´t do 4.17) 16
  13. 13.  Newest - the atom has no definite shape and electrons don´t have precise orbits, they are in clouds  It´s a theory based on the quantum. A quantum is a specific amount of energy that can cause an electron to change its level.
  14. 14. A quantum of energy move an electron up in its energy level.
  15. 15. And... a quantum of energy is released when an electron moves down an energy level.
  16. 16. The 4 quantum numbers describe the electron´s energy level shape. N= level. distance from nucleus L=shape geometry. Sublevel (s,p,d,f) M= magnetic #, orientation of the electron S= spin of e-
  17. 17. Electron configuration  Start at the beginning of each arrow, and follow it all to the end 1st Quantum # =n= the # of sub-levels If n=1 one sublevel (s) n=2 2 sublevels (s, p) n=3 3 sub-levels (s, p, d) n=4 4 sub-levels (s, p, d, f)
  18. 18. Electron Configuration  How electrons are distributed among the energy levels . He:1s2  The large number "1" refers to the principle quantum number "n" (the energy level).  electrons occupy an "s" or spherical orbital.  The exponent "2" is the total number of electrons in that orbital
  19. 19.  Sublevel # of orbitals Maximum number of electrons s 1 2 p 3 6 d 5 10 f 7 14  The valence shell or outer shell (highest energy level) is the responsible for how an element reacts to form compounds.  Find the electron configuration of: Cl, Na, Cr, Ne, Fe
  20. 20. Principles of Aufbau, Pauli’s exclusion and Hund’s rule to write electronic configurations  3 Rules for filling orbitals  Aufbau principle: Electrons enter the orbital of lowest energy first  Pauli exclusion principle: Only 2 electrons in an orbital and they cannot have the same spin, up or down. (PS: S orbitals are spheric, P orbitals are like dumbbells )  Hund´s Rule: When electrons occupy equal energy levels, one electron enters each orbital until all the orbitals contain one electron with parallel spin. Then you can add more electrons to the orbital with opposite spin.  Using the 3 rules do the electron conf, of Mg, O , Cu, and Cr
  21. 21.  Return to previous page  Aufbau Diagram of Principal Energy Levels, Sublevels and Orbitals  7s  6p  5d  4f  6s  5p  4d  5s  4p   3d  4s  3p   3s  2p  2s   1s  Each box represents an atomic orbital which can hold up to 2 electrons with opposite spins.
  22. 22. 12 24 Mg __ ___ __ __ __ __ 1s2 2s2 2p6 3s2 8 16 O __ __ __ __ __ 1s2 2s2 2p6 29 63 Cu __ __ __ __ __ __ __ __ __ __ 1s2 2s2 2p6 3s2 3p6 4s2 ___ ___ ___ ___ ___ 3d10
  23. 23. Ions  Ion: group of atoms that has a positive or negative charge;  cations - ions with a positive charge: Metals tend to form cations anions - ions with a negative charge. Nonmetals tend to form anions  Table salt, sodium chloride NaCl in water forms the ions: Na+ and Cl-  Try to figure out why Na is a cation and Cl is an anion  11 17  23 Na 35 Cl  Do p67 problem  Do electron configuration of: Na +1, Cl -1, Mg +2, O-2 Read exercise from page 44, do problems from page 50 # 39-43
  24. 24. Lewis dot diagram  Another way of showing electron configuration is the Lewis or electron dot diagrams.  Write the elements symbol and draw a group of 1-8 dots, which shows the electrons in the outer or valence shell. (for H and He only 2 e- )  example : oxygen  you need to know how many electrons are in the valence shell. The electron configuration of oxygen is 1s2 2s2 2p4    You fill in one valence electron on each side of the elemental symbol, and then double up as many sides as needed  The electrons that are unpaired are the ones that take part in chemical reactions.  Try drawing the dot diagrams for Li, Na, Cl, H, He, B, N , KCl, NH3, CaBr2, H2O, CH4, AlF3
  25. 25. Chapter 4 Atoms and Elements 4.4 Atomic Number and Mass Number 32S, 33S, 34S, 36S 16 16 16 16 Copyright © 2008 by Pearson Education, Inc. 30 Publishing as Benjamin Cummings
  26. 26. Atomic Number The atomic number • Is specific for each element. • Is the same for all atoms of an element. • Is equal to the number of protons in an atom. • Appears above the symbol of an element. Atomic Number 11 Symbol Na 31
  27. 27. Atomic Numbers and Protons Examples: • Hydrogen has atomic number 1, every H atom has one proton. • Carbon has atomic number 6, every C atom has six protons. • Copper has atomic number 29, every Cu atom has 29 protons. • Gold has atomic number 79, every Au atom has 79 protons. 32
  28. 28. Atomic Models Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings 33
  29. 29. Learning Check State the number of protons in each. A. A nitrogen atom 1) 5 protons 2) 7 protons 3) 14 protons B. A sulfur atom 1) 32 protons 2) 16 protons 3) 6 protons C. A barium atom 1) 137 protons 2) 81 protons 3) 56 protons 34
  30. 30. Solution State the number of protons in each. A. A nitrogen atom 2) atomic number 7; 7 protons B. A sulfur atom 2) atomic number 16; 16 protons C. A barium atom, 3) atomic number 56; 56 protons 35
  31. 31. Electrons in An Atom • An atom of any element is electrically neutral; the net charge of an atom is zero. • In an atom, the number of protons is equal to the number of electrons. number of protons = number of electrons • For example, an atom of aluminum has 13 protons and 13 electrons. The net charge is zero. 13 protons (13 +) + 13 electrons (13 -) = 0 36
  32. 32. Mass Number The mass number • Represents the number of particles in the nucleus. • Is equal to the Number of protons + Number of neutrons Table 4.6 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings 37
  33. 33. Learning Check An atom of zinc has a mass number of 65. A. How many protons are in this zinc atom? 1) 30 2) 35 3) 65 B. How many neutrons are in the zinc atom? 1) 30 2) 35 3) 65 C. What is the mass number of a zinc atom that has 37 neutrons? 1) 37 2) 65 3) 67 38
  34. 34. Solution An atom of zinc has a mass number of 65. A. How many protons are in this zinc atom? 1) 30 (atomic number 30) B. How many neutrons are in the zinc atom? 2) 35 (65 – 30 = 35) C. What is the mass number of a zinc atom that has 37 neutrons? 3) 67 (30 + 37 = 67) 39
  35. 35. Learning Check An atom has 14 protons and 20 neutrons. A. Its atomic number is 1) 14 2) 16 3) 34 B. Its mass number is 1) 14 2) 16 3) 34 C. The element is 1) Si 2) Ca 3) Se 40
  36. 36. Solution An atom has 14 protons and 20 neutrons. A. It has atomic number 1) 14 B. It has a mass number of 3) 34 (14 + 20 = 34) C. The element is 1) Si (Atomic number 14) 41
  37. 37. Chapter 4 Atoms and Elements 4.5 Isotopes and Atomic Mass 24Mg 25Mg 26Mg 12 12 12 Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings 42
  38. 38. Isotopes Isotopes • Atoms of the same element that have same number of protons, but different numbers of neutrons, so……different mass numbers. 43
  39. 39. Examples isotopes
  40. 40. Learning Check Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of the following. 12C 13C 14C 6 6 6 protons ______ ______ ______ neutrons ______ ______ ______ electrons ______ ______ ______ 45
  41. 41. Solution Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of the following. 12C 13C 14C 6 6 6 protons 6 p+ 6 p+ 6 p+ neutrons 6 n 7n 8n electrons 6 e- 6 e- 6 e- 46
  42. 42. Ions  Ion: atom(s) that has a positive or negative charge  cations – ions with a positive charge, give electrons, Metals tend to form cations anions – ions with a negative charge. receive electrons , Nonmetals tend to form anions  Table salt, sodium chloride NaCl in water forms the ions: Na+ and Cl -  Try to figure out why Na is a cation and Cl is an anion  Do protons,,neutrons and electrons of : Na +1, Cl -1, Mg +2, O-2

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