23 V Vanadium 50942 2 8 11 2. Periodic Table of Element Groups. File Electron Shell 020 Calcium Svg Wikimedia Commons Potassium Atom Electron Configuration Atomic Structure Also a single glutaraldehyde molecule may form direct cross links if the steric arrangement of adjacent peptides allow it. . Also the real electron configuration of an atom may differ from the prediction because of relativistic effects shielding etc. When an oxygen atom forms a single chemical bond it shares one of its own electrons with the nucleus of another atom and receives in return a share of an electron from that atom. Element Calcium Ca Group 2 Atomic Number 20 s-block Mass 40078. An electron shell is the set of allowed states that share the same principal quantum number n the number before the letter in the orbital label that electrons. Electron configuration was first conceived under the Bohr model of the atom and it is still common to speak o...