The Bohr model of lithium contains a nucleus and two shells, the first with two electrons and the second with one electron. Because of electron affinity, the two electrons in the first shell are relatively close together. The nucleus includes three protons and four neutrons, according to ChemicalElements.com
GreenPlanetSolarEnergy.com uses the analogy of an onion to describe Bohr models of atoms. The orbitals are like the layers of the onion that surround a solid core scientists call the nucleus. Only the outer layer of the onion turns brown as only the outer electron shells allow the atom to react. Each of these shells has the ability to contain a certain number of electrons. With lithium, the two electrons fill the inner shell, but the outer shell has room for an additional seven electrons for a total of eight.
With its almost empty outer shell, elemental lithium is highly reactive and does not occur in its free form in nature. In the chemical laboratory, the metal is stored in paraffin oil to reduce it reaction with water in the form of moisture from the air. The metal burns easily at room temperature creating a bright white flame. In flame tests, lithium compounds create a bright red color.