Encyclopedia of Earth
Encyclopedia of Earth: Biogeochemistry: Phosphorus Cycle
Article explaining what the phosphorus cycle is, where it occurs, its place in the biotic world, and the environmental impact of human activities on the phosphorus cycle. (Published: October 8, 2009)
Science Struck
Science Struck: Ground State vs. Excited State of an Atom
Explains what Bohr's model of the atom is, the characteristics of the ground and excited states of an atom, and the electron configuration for each in the example of Phosphorus.