A168208 Irregular table of the number of electrons of the n-th element of the PSE in atomic shells, read by rows.

1, 2, 2, 1, 2, 2, 2, 3, 2, 4, 2, 5, 2, 6, 2, 7, 2, 8, 2, 8, 1, 2, 8, 2, 2, 8, 3, 2, 8, 4, 2, 8, 5, 2, 8, 6, 2, 8, 7, 2, 8, 8, 2, 8, 8, 1, 2, 8, 8, 2, 2, 8, 9, 2, 2, 8, 10, 2, 2, 8, 11, 2, 2, 8, 13, 1, 2, 8, 13, 2, 2, 8, 14, 2, 2, 8, 15, 2, 2, 8, 16, 2, 2, 8, 18, 1, 2, 8, 18, 2, 2, 8, 18, 3, 2, 8, 18, 4, 2

Offset: 1

Author

Paul Curtz, Nov 20 2009

Keywords

• nonn
• less
• tabf

Comments

For the n-th element in the periodic system of elements, row n of the table shows the occupancy of the K-shell, then the L-shell, then the M-shell etc.

Row sums are A000027(n). A093907(c) is the maximum number that may appear in column c.

How are rows defined when the n-th element has more than one possible electron configuration? For example, element no. 28 (Nickel) has two electron configurations, namely 2, 8, 16, 2 and 2, 8, 17, 1, and it is disputed which of them is the ground state configuration of Nickel. - Felix Fröhlich, Jun 02 2019

Examples

			From _Felix Fröhlich_, Jun 02 2019: (Start)
Irregular table starts as follows, where Z denotes the atomic number:
  Z  | Element name | Electrons per shell
  -----------------------------------------
   1 | Hydrogen     | 1
   2 | Helium       | 2
   3 | Lithium      | 2, 1
   4 | Beryllium    | 2, 2
   5 | Boron        | 2, 3
   6 | Carbon       | 2, 4
   7 | Nitrogen     | 2, 5
   8 | Oxygen       | 2, 6
   9 | Fluorine     | 2, 7
  10 | Neon         | 2, 8
  11 | Sodium       | 2, 8,  1
  12 | Magnesium    | 2, 8,  2
  13 | Aluminium    | 2, 8,  3
  14 | Silicon      | 2, 8,  4
  15 | Phosphorus   | 2, 8,  5
  16 | Sulfur       | 2, 8,  6
  17 | Chlorine     | 2, 8,  7
  18 | Argon        | 2, 8,  8
  19 | Potassium    | 2, 8,  8, 1
  20 | Calcium      | 2, 8,  8, 2
  21 | Scandium     | 2, 8,  9, 2
  22 | Titanium     | 2, 8, 10, 2
  23 | Vanadium     | 2, 8, 11, 2
  24 | Chromium     | 2, 8, 13, 1
  25 | Manganese    | 2, 8, 13, 2
  26 | Iron         | 2, 8, 14, 2
  27 | Cobalt       | 2, 8, 15, 2
(End)
		

Links

• Wikipedia, Electron configurations of the elements (data page)

Crossrefs

Cf. A173642.

Extensions

Redefined as an irregular table by R. J. Mathar, Dec 05 2009

Edited by Felix Fröhlich, Jun 02 2019