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Chapter 5 Electrons in Atoms

Chapter 5 Electrons in Atoms. Anything in black letters = write it in your notes (‘knowts’). 5.1 – Revising the Atomic Model. Rutherford’s Planetary Model of the Atom. Electrons moving around a tiny nucleus. Problems with Rutherford’s Model

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Chapter 5 Electrons in Atoms

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  1. Chapter 5 Electrons in Atoms Anything in black letters = write it in your notes (‘knowts’)

  2. 5.1 – Revising the Atomic Model Rutherford’s Planetary Model of the Atom Electrons moving around a tiny nucleus

  3. Problems with Rutherford’s Model • Did not explain the chemical properties of the elements. • Did not explain atomic spectra (…later…) • e- would spiral into the nucleus, but they don’t

  4. The Bohr Model ~1913 Electrons are found only in specific locations (or energy levels) around the nucleus. To move from one energy level to another, an e- must gain or lose a quantum of energy. Niels Bohr

  5. The energy levels in atoms are unequally spaced, like the rungs in this unusual ladder. The higher energy levels are closer together.

  6. Electron cloud The Quantum Mechanical Model The modern description of e- in atoms. Similar to Bohr Model except the exact location of an electron is impossible to know Electrons are likely to be found in electron ‘clouds’ around the nucleus We will use the Bohr model in this class…

  7. Atomic orbital – Most probable place for e- to be. Orbitals can hold 2 e- maximum. The orbitals are named s, p, d & f

  8. S (1 type) p (3 types) d (5 types) There are 7 types of f orbitals Don’t worry about these shapes…

  9. x 2 2 x 2 6 x 2 10 x 2 14 Each orbital can hold 2 e- maximum

  10. This chart is on page 132 1s(1 orbital) 2 8 2s(1 orbital), 2p(3 orbitals) 3s(1 orbital), 3p(3 orbitals), 3d(5 orbitals) 18 4s(1 orbital), 4p(3 orbitals), 4d(5 orbitals), 4f(7 orbitals) 32

  11. ASSIGN: Read 5.1 Lesson Check 5.1 (#1-7) page 132

  12. 5.2 – Electron Arrangement in Atoms Aufbau Principle – e- occupy the orbitals of lowest energy first. Pauli Exclusion Principle – Hund’s Rule – we will not cover

  13. 6p 5d 4f 6s 5p 4d 5s 4p 3d 4s 3p 3s Increasing energy 2p 2s E- fill the lowest energy orbitals first Notice the 4s fills before the 3d 1s Aufbau Diagram (p. 135)

  14. Another Aufbau Diagram (write this one down!) Aufbauprinzip, (german) "building-up principle”

  15. Electron Configuration – shows how e- are arranged in an atom Example:Write the electron configuration for N How many e-? Use Aufbau Diagram 7 # of e- in orbitals 1s 2s 2p 2 2 3

  16. Your turn… Write the electron configuration for a) boron b) silicon c) sulfur

  17. Chapter 5 QUIZ!! RIGHT LEFT 1. What is the maximum number of electrons that can go into p orbital d orbital 2. What is the maximum number of electrons in the p orbitals d orbitals 3. Write the electron configuration for N Mg Cl Mg K C

  18. Can you see how the periodic table can be used as an Aufbau Diagram?

  19. ASSIGN: Read 5.2 Answer questions #8-14 page 136,137

  20. Low energy ( = 700 nm) High energy ( = 380 nm) Frequency  (s-1) 3 x 106 3 x 1012 3 x 1022 10-8 10-14 102 5.3 – Atomic Emission Spectra and the Quantum Mechanical Model The Electromagnetic Spectrum (p. 139)

  21. A prism separates light into the colors it contains. White light produces a rainbow of colors. Screen Prism Slit Light bulb

  22. Light from a helium lamp produces discrete lines. Screen Slit Prism Helium lamp

  23. The lines that result are unique for each element and are called its atomic emission spectrum.

  24. Bohr’s Model explained the emission spectra When an atom absorbs energy an electron jumps to a higher energy level (excited state). The electron returns to the lower energy level, emitting a photon with a definite energy. The photon’s energy shows up as a line in the emission spectrum.

  25. Chapter 5 Quick Quiz • Explain the main difference between the Bohr Model and the Quantum Model of the atom. • An atomic orbital can hold a maximum of _____ electrons. • How many types of s, p, d, and f orbitals are there? • s = ______, p = _______, d = ______, f = ______ • What is the maximum e- capacity of the • s orbitals ____, p orbitals ____, d orbitals ____, f orbitals ____

  26. Write the electron configuration for the following elements. • Helium (Z = 2) • Strontium (Z = 38) • Aluminum (Z = 13) • Chlorine (Z=17) • Silver (Z = 47) • Arsenic (Z = 33)

  27. Write the electron configuration for the following elements. • Helium (Z = 2) • Strontium (Z = 38) • Aluminum (Z = 13) • Chlorine (Z=17) • Silver (Z = 47) • Arsenic (Z = 33)

  28. Chapter 5 Things to Know… Rutherford  Bohr  Quantum Mechanical Models, Energy Levels, Atomic Orbitals (s, p, d, f) , Aufbau Principle & Diagram, Electron Configurations, Explanation of Atomic Emission Spectra

  29. Big Sale at the Nuclear Mall today! Make sure to get the closest parking stall. Nuclear Mall 1s 2p 2s 2p 3p 3s 3p 3d 3d 4p 4s 4p 4d 4d

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