5.3. Electron Arrangement in Atoms http://www.ck12.org
TABLE5.7:(continued)
Element Name Symbol Atomic Number Electron Configuration
Gadolinium Gd 64 [Xe] 4 f^75 d^16 s^2
Terbium Tb 65 [Xe] 4 f^96 s^2
Dysprosium Dy 66 [Xe] 4 f^106 s^2
Holmium Ho 67 [Xe] 4 f^116 s^2
Erbium Er 68 [Xe] 4 f^126 s^2
Thulium Tm 69 [Xe] 4 f^136 s^2
Ytterbium Yb 70 [Xe] 4 f^146 s^2
Lutetium Lu 71 [Xe] 4 f^145 d^16 s^2
Hafnium Hf 72 [Xe] 4 f^145 d^26 s^2
Tantalum Ta 73 [Xe] 4 f^145 d^36 s^2
Tungsten W 74 [Xe] 4 f^145 d^46 s^2
Rhenium Re 75 [Xe] 4 f^145 d^56 s^2
Osmium Os 76 [Xe] 4 f^145 d^66 s^2
Iridium Ir 77 [Xe] 4 f^145 d^76 s^2
Platinum Pt 78 [Xe] 4 f^145 d^96 s^1
Gold Au 79 [Xe] 4 f^145 d^106 s^1
Mercury Hg 80 [Xe] 4 f^145 d^106 s^2
Thallium Tl 81 [Xe] 4 f^145 d^106 s^26 p^1
Lead Pb 82 [Xe] 4 f^145 d^106 s^26 p^2
Bismuth Bi 83 [Xe] 4 f^145 d^106 s^26 p^3
Polonium Po 84 [Xe] 4 f^145 d^106 s^26 p^4
Astatine At 85 [Xe] 4 f^145 d^106 s^26 p^5
Radon Rn 86 [Xe] 4 f^145 d^106 s^26 p^6The seventh period starts with francium (Fr) and the 7ssublevel. This is followed by the 5fand 6dsublevels. The
seventh period is incomplete and consists largely of artificial and very unstable elements. Electron configurations
for the known seventh period elements are listed below (Table5.8).
TABLE5.8: Electron Configurations of Seventh-Period Elements
Element Name Symbol Atomic Number Electron Configuration
Francium Fr 87 [Rn] 7 s^1
Radium Ra 88 [Rn] 7 s^2
Actinium Ac 89 [Rn] 6 d^17 s^2
Thorium Th 90 [Rn] 6 d^27 s^2
Protactinium Pa 91 [Rn] 5 f^26 d^17 s^2
Uranium U 92 [Rn] 5 f^36 d^17 s^2
Neptunium Np 93 [Rn] 5 f^46 d^17 s^2
Plutonium Pu 94 [Rn] 5 f^67 s^2
Americium Am 95 [Rn] 5 f^77 s^2
Curium Cm 96 [Rn] 5 f^76 d^17 s^2
Berkelium Bk 97 [Rn] 5 f^97 s^2
Californium Cf 98 [Rn] 5 f^107 s^2
Einsteinium Es 99 [Rn] 5 f^117 s^2
Fermium Fm 100 [Rn] 5 f^127 s^2
Mendelevium Md 101 [Rn] 5 f^137 s^2
Nobelium No 102 [Rn] 5 f^147 s^2