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Electrons In Atoms

Electrons In Atoms. Electromagnetic Radiation. Form of energy that exhibits both wavelike behaviors and particle behaviors . Electromagnetic Spectrum. Shows all forms of electromagnetic radiation. Quanta. Electrons gain/lose energy in set increments only

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Electrons In Atoms

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  1. Electrons In Atoms

  2. Electromagnetic Radiation • Form of energy that exhibits both wavelike behaviors and particle behaviors

  3. Electromagnetic Spectrum • Shows all forms of electromagnetic radiation

  4. Quanta • Electrons gain/lose energy in set increments only • Each set amount of energy is called a quantum • Lost energy is released as electromagnetic radiation, with more energy = higher frequency

  5. Photoelectric Effect • Emission of electrons from metal’s surface when light of specific frequency shines on surface light e- METAL

  6. Wrap-Up #1 • If electrons will only be emitted by light of high energy, which of the following is more likely to release electrons? • Blue light with low intensity (dim) • Red light with high intensity (bright) • Radio waves with high intensity

  7. Bohr Model – Electron States • Ground State • Lowest energy state of an electron • Where the electron is “naturally” • Excited State • State when an electron gains energy • Only exists while energy is being absorbed by the atom • Glow in the dark materials – the electrons absorb energy from light and re-release it as light when its surroundings are dark

  8. Bohr Model E1 = lowest energy level E3 > E2 > E1 E1 E2 E3

  9. in ground state, no energy radiated in excited state, electrons jump to higher energy level (because they’ve absorbed energy from an external source) electrons go from high E level to low E level photon emitted Ground State to Excited State 4 6 5 4 3 3 2 Energy of atom 2 1 1

  10. Atomic Orbitals • Volume surrounding the nucleus in which an electron is 90% likely to be found

  11. Principle Quantum Number (n) • Indicates the energy level an electron is on • Use periodic table to tell • The period number corresponds to the principle quantum number (n = 1,2,3…)

  12. Energy Orbitals • Shape of orbital that tells the path of the electrons • 4 orbitals: s, p, d, f • The letter tells you the shape of the orbital

  13. s orbital • Shape: electrons travel in a sphere

  14. s orbital 3s 1s 2s The greater the energy level, the bigger the orbital

  15. p orbital • Shape: dumbbell or figure 8 shaped

  16. d orbital • Shape – double dumbbells or a dumbell with a ring around it

  17. Electron Configuration • Description of the arrangement of electrons in an atom • Allows us to visualize where the electrons in an atom can be found

  18. Rules Governing Electron Configurations 1) Aufbau Principle – electrons occupy lowest energy orbital available - fill up level 1 first, then level 2, etc. 2) Pauli Exclusion Principle – there is a max number of electrons that occupy a single orbital (2) and they must have opposite spin

  19. Rules Governing Electron Configurations 3) Hund’s Rule – if orbitals have equal energy, one e- will go in each orbital before doubling up 1 2 3 5 6 4

  20. Rules Governing Electron Configurations 3b) Hund’s Rule – all electrons in singly occupied orbitals must have the same spin Yes Yes Yes NO NO NO

  21. Blocks On Periodic Table s s p d f

  22. Divisions of Orbitals • s orbital – 1 sublevel (2 e- max) • p orbital – 3 sublevels (6 e- max) • d orbital – 5 sublevels (10 e- max) • f orbital – 7 sublevels (14 e- max)

  23. Orbital Diagram • Nitrogen • How many electrons? 7 1s 2s 2p

  24. Orbital Diagram • Silicon • How many electrons? 14 1s 2s 2p 3s 3p

  25. Wrap-Up #2: Orbital Diagram • Copper • How many electrons? 29 1s 2s 2p 3s 3p 4s 3d

  26. Electron Configuration Notation • Oxygen (8 e-) • Sulfur (16 e-) • Vanadium (23 e-) 2 2 4 2s 2p 1s 2 2 6 2 4 2s 2p 3s 3p 1s 2 2 6 2 6 2 3 2s 2p 3s 3p 4s 3d 1s

  27. Noble Gas Notation • Rule: start from previous noble gas, then write the configuration • Oxygen • Sulfur • Vanadium 2 4 [He] 2s 2p 2 4 [Ne] 3s 3p 2 3 [Ar] 4s 3d

  28. Valence Electrons • Electrons in outer most energy level - located in highest s & p orbitals N: Mg: Se: 2 2 3 5 valence e- 1s 2s 2p 2 2 6 2 2 valence e- 1s 2s 2p 3s 2 2 6 2 6 2 10 4 1s 2s 2p 3s 3p 4s 3d 4p 6 valence e-

  29. Electron Dot Structure • Shows valence electrons in a diagram • Nitrogen (5 v.e.) • Magnesium (2 v.e.) • Selenium (6 v.e.) N Mg Se

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