Here is an Interactive Table of Elements where you can learn more about each of the elements. Every atom would like to have an electron configuration like a noble gases. In noble gases the outer electron shell is complete. This makes the element chemically inert. It is not present in organisms because it is not chemically reactive.
Electrons move from one energy state to another but can only exist aft defineite energy levels.
The energy absorbed or released when electrons change states is in the form of electromagnetic radiation. The Bohr model was only able to explain the very simplest atoms, like hydrogen. Today's modern day theory is based on mathematics and the properties of waves. The wave model forms the basis for the Quantum Theory . This theory gives the probability of locating electrons in a particular location, unlike assuming electrons orbit the nucleus as in the Bohr model.