is to say, unstable. Substances such as BH3 are referred to as electron-deficient molecules, and are very reactive towards electron-rich substances. B + 3 H B H Possible but highly reactive. Boron shares only 6 electrons. H H H Aluminum, which is also in group III, exhibits similar behaviour. Al + 3 H Al H Electron-deficient substance H H elecstrpp.dvi. 5. Electronic structure of the elements 1. 5. Electronic Structure of the Elements. Table 5.1. Reviewed 2011 by J.E. Sansonetti (NIST). The electronic configurations and the ionization energies are from the NIST database, “Ground Levels and Ionization Energies for the Neutral Atoms,” W.C. Martin, A. Musgrove, S. Kotochigova Iodine has 53 electrons and a configuration of 2, 8, 18, 18, 7. Why does the fourth shell not reach maximum and therefore it picks up 7 electrons and begins a new shell? Write the noble gas electron configuration for tellurium. - First shell: 2 electrons (2 x 1^2 = 2) - Second shell: 8 electrons (2 x 2^2 = 8) - Third shell: 18 electrons (2 x 3^2 = 18) Now, when we move to the fourth shell, according to the formula, it should hold a maximum of 32 electrons (2 x 4^2 = 32). However, the actual electron configuration of iodine only fills up to 18 electrons in the third Answer 1: Calcium has 20 electrons so the full electronic configuration is: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2. The 4s orbital is lower in energy than the 3d subshell and is therefore filled first. The shorthand version is [Ar] 4s 2 since argon is the nearest preceding noble gas to calcium which accounts for 18 electrons. The next largest atom, beryllium, has 4 electrons, so its electron configuration is 1s 2 2s 2. Now that the 2s subshell is filled, electrons in larger atoms start filling the 2p subshell. Thus, the electron configurations for the next six atoms are as follows: B: 1s 2 2s 2 2p 1; C: 1s 2 2s 2 2p 2; N: 1s 2 2s 2 2p 3; O: 1s 2 2s 2 2p 4; F: 1s 2 Iodine would have a standard electron configuration of 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^10 5p^5 The noble gas in the row above iodine is krypton. We can replace 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 with the symbol [Kr] and rewrite the noble gas configuration of iodine as [Kr] 5s^2 4d^10 5p^5 I hope this was helpful. Information • Atomic Number: 53 • Atomic Symbol: I • Atomic Weight: 126.9045 • Electron Configuration: 2-8-18-18-7 • Melting Point: 113.5oC • Boiling Point: 184oC. Properties • Iodine is a bluish-black solid that at room temperatures into a blue-violet gas with an irritating odor • It forms compounds with many elements, but is Elements Iodine (I) Iodine (I) Iodine is a chemical element of the periodic table with chemical symbol I and atomic number 53 with an atomic weight of 126.904 u and is classed as nonmetal and is part of group 17 (fluorine group). Iodine is solid at room temperature. Tellurium Periodic table Xenon Iodine in the periodic table Learn iodine atomic number, atomic mass of iodine and iodine uses. Login. Study Materials. Electron configuration [Kr] 4d 10 5s 2 5p 5: CAS number: 7553-56-2 AHkYM0p.