Quantum Theory

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Quantum Theory
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First Model

• Good until Rutherford there was a positively
  charged nucleus

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Rutherfords Model

• How are the e-s arranged?
• Why arent they pulled into nucleus?
• Why dont all elements behave the same way?

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Neils Bohr

• Worked with H to create the next model of the
  atom

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Bohrs Planetary Atomic Model

• e-s move in circular orbits (paths) and e-s
  are considered particles
• Each orbit has its own energy level (n1,
  n2,n3,n4,etc)
• Smaller orbitsless energy
• Larger orbitsmore energy
• As long as an e- stays in its allowed orbit, it
  will not emit or absorb energy
• This is why we dont see light if we are not
  exposing it to heat!

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Energy Levels

• e-s change energy levels one at a time
• Ground state is lowest allowed
• If it jumps from lower to higher, it will absorb
  energy and become excited
• e- needs energy to move from lower to higher
  energy levels

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Excited State
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What goes upmust come down!

• When an e- moves from higher to lower energy
  level, it will release energy that we can see as
  light and it becomes de-excited
• Every time an e- drops, it emits light

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Goodbut not great

• Bohrs model was good
• But only worked for H

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DeBroglies Theory

• Proposed e-s moved in wave-like motions

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Heisenberg Uncertainty Principle

• Based on the idea that it is impossible to know
  the exact location of the e-
• We dont know exactly where the e- is in orbit
• We dont know the exact velocity
• Supports DeBroglies theory that the orbit
  behaves like a wave

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Schrodingers Quantum Mechanical Model of the
Atom modern model

• Dense, positively charged nucleus
• e-s treated as waves, not particles
• Orbits are no longer described
• Good probability of finding the e- in an atomic
  orbital
• Atomic Orbital 3D region around a nucleus that
  describes e- probable location

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Atomic orbital

• 3D area where there is a HIGH probability of
  finding an electron
• n is a principal energy level that can be
  divided into sublevels
• The higher the principal energy level, the
  farther the e- is from the nucleus

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Sublevels

• n 1 1 sublevel
• n 2 2 sublevels
• n 3 3 sublevels
• n 4 4 sublevels
• Sublevels are divisions of the principal energy
  levels that contain orbitals
• Labeled s,p,d,f

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s,p,d,f

• Sublevel s has 1 orbital
• Sublevel p has 3 orbitals
• Sublevel d has 5 orbitals
• Sublevel f has 7 orbitals

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Examples

• n 1 has 1 sublevel 1s
• n 2 has 2 sublevels 1s,2p
• n 3 has 3 sublevels 1s,2p,3d
• n 4 has 4 sublevels 1s,2p,3d,4f

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Orbitals

• An orbital is a space that can hold a MAX of 2 e-
  at a time

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Putting it all together

• The principal energy levels are divided into
  sublevels that are divided into orbitals that
  hold a MAX of 2 e- per orbital
• e-s only occupy one orbital at a time
• They could occupy the others if they become
  excited

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Electron Configuration

• A. Shows how much energy an e- has (1s is lower
  energy than 2s, 2p is higher than 2s, etc.)
• B. how electrons are distributed within the
  orbitals of the sublevels in a principal energy
  level (are the e- in the s, p, d, or f sublevel)
• Series of numbers, letters, and superscripts

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Aufbau Principle

• Follow to write e- configuration
• states that electrons will occupy the lowest
  principle energy level, sublevel, and orbitals
  FIRST because these are the most stable (closest
  to the ground state).

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The Aufbau Order Memorize!
Notice 4s is filled before 3d Need of e- to
follow this!
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Oh my gosh!!!!!

• Have you had enough yet??????????
• Dont hate me too much!