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“Electrons in Atoms” ECN

“Electrons in Atoms” ECN. Why was the Quantum Mechanical Model Developed?. Bohr and Rutherford’s models did not fully explain the atom Energy is “quantized” - It comes in chunks. A quantum is the amount of energy needed to move from one energy level to another.

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“Electrons in Atoms” ECN

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  1. “Electrons in Atoms”ECN

  2. Why was the Quantum Mechanical Model Developed? • Bohr and Rutherford’s models did not fully explain the atom • Energy is “quantized” - It comes in chunks. • A quantum is the amount of energy needed to move from one energy level to another. • Since the energy of an atom is never “in between” there must be a quantum leap in energy.

  3. How is the QMM Described? • Has energy levels for electrons. • Orbits are not circular. • It can only tell us the probability of finding an electron a certain distance from the nucleus.

  4. Where are the Electrons in the QMM? • The atom is found inside a blurry “electron cloud” • An area where there is a chance of finding an electron. • Think of fan blades

  5. How are the energy levels arranged? # of shapes (orbitals) Maximum electrons Starts at energy level 2 s 1 1 6 p 3 2 10 5 3 d 14 7 4 f

  6. http://www.d.umn.edu/~pkiprof/ChemWebV2/AOs/index.html

  7. What are Electron Configurations ?… • …the way electrons are arranged in various orbitals around the nuclei of atoms. Three rules tell us how: • Aufbau principle- electrons enter the lowest energy first. • Pauli Exclusion Principle- at most 2 electrons per orbital - different spins • Hund’s Rule- When electrons occupy orbitals of equal energy, they don’t pair up until they have to.

  8. What do the ECN numbers mean? Number of electrons 1s2 Energy Level (period) Orbital block

  9. ECN Number of electrons 1s2 Energy level (Period) Orbital block

  10. What is the ECN order? • 1s2 • 2s22p6 • 3s23p6 • 4s23d104p6 • 5s24d105p6 • 6s24f145d106p6 • 7s25f146d107p6

  11. Changing the energy • Let’s look at a hydrogen atom, with only one electron, and in the first energy level.

  12. Changing the energy • Heat, electricity, or light can move the electron up to different energy levels. The electron is now said to be “excited”

  13. Changing the energy • As the electron falls back to the ground state, it gives the energy back as light

  14. Changing the energy • They may fall down in specific steps • Each step has a different energy

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