Chapter 4 Notes

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1. Subatomic Particles

Electrons

Negatively charged particle

Electron cloud around nucleus

Both a wave & particle like nature

Heisenberger Uncertainty Principle - t is impossible to simultaneously know the position and momentum of the electron

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2. The Electronic Structure of Atoms

Quantum Numbers

(n, l, ml, ms)

n = energy level (corresponds to row in periodic table)

l = angular momentum (0

ml = magnetic quantum number, (-l

ms = +1/2 or -1/2

Atomic Orbitals

s

spherical, symmetric

one orbital/level (2 electrons)

p

starts at the n = 2 shell

peanut shaped

three orbital/level (6 eletrons)

d

starts at the n = 3 shell

4 clover shaped + 1 peanut in a doughnut shaped

five orbital/level (10 electrons)

f

starts at the n = 4 shell

seven orbital/level (14 electrons)

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3. Electron Configurations

Pauli Exclusion Principle

No two electrons in an atom can have the same four quantum numbers

Visualize electrons in the orbital spinning in different directions

Aufbau Principle

The electron that distinguishes the element from the previous element enters the lowest energy atomic orbital available - filling the orbitals from the lowest to the highest

Hund's Rule

The most stable arrangement is the one with the greatest number of parallel spins