Integrated SequencePhysics Chemistry Organic Biology

Web Resources

Chem1 Virtual Textbook - Periodic Properties
Well written and illustrated introduction to the periodic properties.

HyperPhysics - Ionization Energy and Electron Affinity

Purdue University - Size of Atoms
Excellent, comprehensive discussion of atomic radius. A bit more detailed than the typical MCAT preparation, so treat some sections as reading comprehension.

Purdue University - Ionization Energy and Electron Affinity
Comprehensive well-designed tutorial.

PY106 Notes - Electric energy and potential
Well-expressed and illustrated introduction to these crucial concepts. Includes an illustration of the concept of electric potential energy in the context of the ionization energy of an atom.

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Special points of emphasis

Work, Energy, and Power


Atomic Theory

Periodic Properties


One of our consistent themes in this MCAT course is how helpful classical electrodynamics can be to understanding chemistry. While quantum electrodynamics provides a better model in many ways, plain old Coulomb's Law does provide useful insight into the periodic properties of atomic radius, ionization energy, and electron affinity. Without trying to be perfectly rigorous, imagine mechanical work against electrostatic force to visualize the energy transformations of the atom represented by each periodic property.

This is fine as long as one does not forget that the events are quantized. Atomic radius decreases as you move rightward on the table. Imagine the stronger, more positive nucleus, pulling the electrons tighter with a stronger electrostatic force. Ionization energy increases moving rightward. Imagine how it would take more work to pull an electron in a given shell away from a nucleus with more protons. You are using imaginative visualization to build your intuition.

The classical picture can help you as long as you know its limitations. Do not be afraid to move between thinking about the periodic properties as if they were describing a simple electrostatic system and the understanding that the periodic properties describe a quantum electrodynamic system.

The WikiPremed MCAT Course is a free comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum.

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