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The Downfall of Classical Physics. Niels Bohr – Quantum Mechanics. Niels Bohr applies Quantum Mechanics to Rutherford’s model and proposes that electrons are located around the nucleus in energy levels. . The Rise of Quantum Physics.
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Niels Bohr – Quantum Mechanics Niels Bohr applies Quantum Mechanics to Rutherford’s model and proposes that electrons are located around the nucleus in energy levels.
The Rise of Quantum Physics Spectral lines can be explained by the movement of electrons from one energy level to another.
ENERGY LEVEL (n) • “Rings” of Bohr’s planetary model • 7 possible energy levels • Maximum number of electrons in each energy level = 2n2 • 1st level: • 2nd level: • 3rd level: 2 8 18
ENERGY SUBLEVELS • 4 types of sublevels: • s • p • d • f • Every energy level begets a new sublevel • Energy level 1: 1 sublevel (s) • Energy level 2: 2 sublevels (s, p)
ORBITALS • s sublevel = 1 s orbital • p sublevel = 3 p orbitals • d sublevel = 5 d orbitals • f sublevel = 7 f orbitals
MAGNETIC SPIN • “Spin up” • “Spin down”
RULES FOR ELECTRONS • An orbital can hold a maximum of TWO electrons • Pauli exclusion principle • Aufbauprinciple • Hund’s rule
Pauli Exclusion Principle • no two electrons can have the same “address” • Energy level • Sublevel • Orbital • Spin
AufbauPrinciple • Electrons will fill the orbitals with the lowest amount of energybefore filling in orbitals that have more energy • Order is: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p
Hund’s Rule • Electrons will not share an orbital of the same energy if there is an empty orbital with that energy is available
Orbital Diagrams Orbital Spin 1 s Energy level Sublevel
Draw an orbital diagram for carbon: 1s 2s 2p
How to draw orbital diagrams • Use periodic table to figure out where to end (energy level and sublevel of last electron) • Draw boxes (orbitals) for all energy levels and sublevels up to the ending point • 1 box for s, 3 boxes for p, 5 boxes for d, 7 boxes for f • Fill boxes with electrons (2 per orbital) with opposite spins • Follow Hund’s rule when in the p, d, or f sublevels
Electron configurations • Based on orbital diagrams • Use numbers and superscripts along with s, p, d and f to show location of electrons in atoms • Coefficient = energy level • Letter = sublevel • Superscript = # of electrons in sublevel
Example: Energy level 2 electrons 1s2 sublevel
Write an electron configuration for nitrogen: 1s 2s 2p 1s22s22p3
Practice • Draw the orbital diagram for oxygen • Write the electron configuration for oxygen 1s 2s 2p 1s22s22p4
Shortcuts!! • Shortcut (shortened) Notation: • Use closest Noble Gas before the element • For bromine: • Closest Noble Gas before the element: • Argon: • Shortcut Notation: 1s22s22p63s23p6 4s23d104p5 1s22s22p63s23p6 [Ar] 4s23d104p5b
What is the electron configuration of potassium? • 1s22s22p63s23p63d1 • 1s22s22p23s23p24s1 • 1s22s22p63s23p3 • 1s22s22p63s23p64s1
Each period number in the periodic table corresponds to _______ A) an atomic mass B) an energy level C) an energy sublevel D) an atomic number