Chapter 13 Electrons

• Models of the Atom• Electron Arrangement• Physics and the Quantum Mechanical

Model

Chapter 13.1 Models of the Atom

• The atom was considered a solid indivisible mass originally

http://www.youtube.com/watch?v=uhgd9VM9rsM

Thomson Model

• Plum – Pudding Atom: Negatively charged electrons stuck into a lump of positively charged material.

Rutherford Model

• Electrons surround a dense nucleus made of protons and neutrons. The rest of the atom was empty space

Bohr Model (Planetary Model)

• Electrons are arranged in concentric circular paths (orbits) around the nucleus.

• Patterned after the motion of the planets • Electrons have a fixed energy

Quantum Mechanical Model

• Primarily a mathematical model • Restricts electron to certain energy levels• No defined path for electrons• Gives a percent chance of finding an

electron in a certain space

http://www.youtube.com/watch?v=xqNSQ3OQMGI

Quantum

• Amount of energy required to move an electron from its current energy level to the next highest energy level

Fixed Energy Levels

• Rungs of a Ladder• Garden Steps

Orbits

• S orbital• P orbital• D orbital • F orbital

Chapter 13.2 Electron Arrangement

• Electron Configurations• Exceptional Electron Configurations

Electron Configurations

• The way in which electrons are arranged around the nuclei of an atom.

• Three Rules:– Aufbau Principle– The Pauli Exclusion Principle– Hund’s Rule

Aufbau Principle

• Electrons enter orbitals of lowest energy first.

• Some orbitals overlap between different energy levels

The Pauli Exclusion Principle

• An atomic orbital may describe at most two electrons

• One or two electrons may occupy one orbital

• They will have opposite spins (shown by opposite arrows)

Hund’s Rule

• When electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with parallel spins.