Periodic table (electron configurations)

  • Configurations of elements 109 and above are not available. Predictions from reliable sources have been used for these elements.
  • Grayed out electron numbers indicate subshells that are filled to their maximum.
  • The bracketed noble gas symbols on the left represent the inner configurations that are the same in each period. Written out these are:
He, 2, helium : 1s2
Ne, 10, neon : 1s2 2s2 2p6
Ar, 18, argon : 1s2 2s2 2p6 3s2 3p6
Kr, 36, krypton : 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
Xe, 54, xenon : 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6
Rn, 86, radon : 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6
Og, 118, oganesson : 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p6
  • Note the non-linear shell ordering, which comes about due to the different energies of smaller and larger shells.

References

See list of sources at Electron configurations of the elements (data page).

Electron configuration

In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. For example, the electron configuration of the neon atom is 1s2 2s2 2p6, using the notation explained below.

Electronic configurations describe each electron as moving independently in an orbital, in an average field created by all other orbitals. Mathematically, configurations are described by Slater determinants or configuration state functions.

According to the laws of quantum mechanics, for systems with only one electron, a level of energy is associated with each electron configuration and in certain conditions, electrons are able to move from one configuration to another by the emission or absorption of a quantum of energy, in the form of a photon.

Knowledge of the electron configuration of different atoms is useful in understanding the structure of the periodic table of elements. This is also useful for describing the chemical bonds that hold atoms together. In bulk materials, this same idea helps explain the peculiar properties of lasers and semiconductors.

Electron shell

In chemistry and atomic physics, an electron shell, or a principal energy level, may be thought of as an orbit followed by electrons around an atom's nucleus. The closest shell to the nucleus is called the "1 shell" (also called "K shell"), followed by the "2 shell" (or "L shell"), then the "3 shell" (or "M shell"), and so on farther and farther from the nucleus. The shells correspond with the principal quantum numbers (n = 1, 2, 3, 4 ...) or are labeled alphabetically with letters used in the X-ray notation (K, L, M, …).

Each shell can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the nth shell can in principle hold up to 2(n2) electrons. Since electrons are electrically attracted to the nucleus, an atom's electrons will generally occupy outer shells only if the more inner shells have already been completely filled by other electrons. However, this is not a strict requirement: atoms may have two or even three incomplete outer shells. (See Madelung rule for more details.) For an explanation of why electrons exist in these shells see electron configuration.The electrons in the outermost occupied shell (or shells) determine the chemical properties of the atom; it is called the valence shell.

Each shell consists of one or more subshells, and each subshell consists of one or more atomic orbitals.

Index of chemistry articles

Chemistry (from Egyptian kēme (chem), meaning "earth") is the physical science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions.Below is a list of chemistry-related articles. Chemical compounds are listed separately at list of organic compounds, list of inorganic compounds or list of biomolecules.

Open shell

In the context of atomic orbitals, an open shell is a valence shell which is not completely filled with electrons or that has not given all of its valence electrons through chemical bonds with other atoms or molecules during a chemical reaction. Atoms generally reach a noble gas configuration in a molecule. The noble gases (He, Ne, Ar, Kr, Xe, Rn) are less reactive and have configurations 1s2 (He),

1s22s22p6 (Ne), 1s22s22p63s23p6 (Ar), etc.

For molecules it signifies that there are unpaired electrons. In molecular orbital theory, this leads to molecular orbitals that are singly occupied. In computational chemistry implementations of molecular orbital theory, open shell molecules have to be handled by either the restricted open-shell Hartree–Fock method or the unrestricted Hartree–Fock method.

Likewise a closed shell or closed shell configuration is obtained with a completely filled valence shell. This configuration is very stable. In another meaning a closed shell configuration corresponds to a state where all molecular orbitals are either doubly occupied or empty (a singlet state). Open shell molecules are more difficult to study computationally

Periodic table (disambiguation)

The periodic table is a tabular arrangement of the chemical elements, ordered by their atomic number, electron configurations, and recurring chemical properties, whose adopted structure shows periodic trends.

Periodic table may also refer to:

The Periodic Table (short story collection), a short story collection by Primo Levi

The Periodic Table (Simon Basher book), a 2007 children's science book

Periodic table (crystal structure)

Periodic table (electron configurations)

Rubidium

Rubidium is a chemical element with the symbol Rb and atomic number 37. Rubidium is a very soft, silvery-white metal in the alkali metal group. Rubidium metal shares similarities to potassium metal and cesium metal in physical appearance, softness and conductivity. Rubidium cannot be stored under atmospheric oxygen, as a highly exothermic reaction will ensue, sometimes even resulting in the metal catching fire.

Rubidium is the first alkali metal in the group to have a density higher than water, so it sinks, unlike the metals above it in the group. Rubidium has a standard atomic weight of 85.4678. On Earth, natural rubidium comprises two isotopes: 72% is a stable isotope 85Rb, and 28% is slightly radioactive 87Rb, with a half-life of 49 billion years—more than three times longer than the estimated age of the universe.

German chemists Robert Bunsen and Gustav Kirchhoff discovered rubidium in 1861 by the newly developed technique, flame spectroscopy. The name comes from the Latin word rubidus, meaning deep red, the color of its emission spectrum. Rubidium's compounds have various chemical and electronic applications. Rubidium metal is easily vaporized and has a convenient spectral absorption range, making it a frequent target for laser manipulation of atoms. Rubidium is not a known nutrient for any living organisms. However, rubidium ions have the same charge as potassium ions and are actively taken up and treated by animal cells in similar ways.

Electron configurations of the neutral gaseous atoms in the ground state

1s:

1
H

1

2
He

2

[He]
+

2s:
2p:

3
Li

1
-

4
Be

2
-

5
B

2
1

6
C

2
2

7
N

2
3

8
O

2
4

9
F

2
5

10
Ne

2
6

[Ne]
+

3s:
3p:

11
Na

1
-

12
Mg

2
-

13
Al

2
1

14
Si

2
2

15
P

2
3

16
S

2
4

17
Cl

2
5

18
Ar

2
6

[Ar]
+

4s:
3d:
4p:

19
K

1
-
-

20
Ca

2
-
-

21
Sc

2
1
-

22
Ti

2
2
-

23
V

2
3
-

24
Cr

1
5
-

25
Mn

2
5
-

26
Fe

2
6
-

27
Co

2
7
-

28
Ni

2
8
-

29
Cu

1
10
-

30
Zn

2
10

-

31
Ga

2
10

1

32
Ge

2
10

2

33
As

2
10

3

34
Se

2
10

4

35
Br

2
10

5

36
Kr

2
10
6

[Kr]
+

5s:
4d:
5p:

37
Rb

1
-
-

38
Sr

2
-
-

39
Y

2
1
-

40
Zr

2
2
-

41
Nb

1
4
-

42
Mo

1
5
-

43
Tc

2
5
-

44
Ru

1
7
-

45
Rh

1
8
-

46
Pd

-
10
-

47
Ag

1
10
-

48
Cd

2
10

-

49
In

2
10

1

50
Sn

2
10

2

51
Sb

2
10

3

52
Te

2
10

4

53
I

2
10

5

54
Xe

2
10
6

[Xe]
+

6s:
4f:
5d:
6p:

55
Cs

1
-
-
-

56
Ba

2
-
-
-

57
La

2
-
1
-

58
Ce

2
1
1
-

59
Pr

2
3
-
-

60
Nd

2
4
-
-

61
Pm

2
5
-
-

62
Sm

2
6
-
-

63
Eu

2
7
-
-

64
Gd

2
7
1
-

65
Tb

2
9
-
-

66
Dy

2
10
-
-

67
Ho

2
11
-
-

68
Er

2
12
-
-

69
Tm

2
13
-
-

70
Yb

2
14

-
-

71
Lu

2
14

1
-

72
Hf

2
14

2
-

73
Ta

2
14

3
-

74
W

2
14

4
-

75
Re

2
14

5
-

76
Os

2
14

6
-

77
Ir

2
14

7
-

78
Pt

1
14
9
-

79
Au

1
14
10

-

80
Hg

2
14
10

-

81
Tl

2
14
10

1

82
Pb

2
14
10

2

83
Bi

2
14
10

3

84
Po

2
14
10

4

85
At

2
14
10

5

86
Rn

2
14
10
6

[Rn]
+

7s:
5f:
6d:
7p:

87
Fr

1
-
-
-

88
Ra

2
-
-
-

89
Ac

2
-
1
-

90
Th

2
-
2
-

91
Pa

2
2
1
-

92
U

2
3
1
-

93
Np

2
4
1
-

94
Pu

2
6
-
-

95
Am

2
7
-
-

96
Cm

2
7
1
-

97
Bk

2
9
-
-

98
Cf

2
10
-
-

99
Es

2
11
-
-

100
Fm

2
12
-
-

101
Md

2
13
-
-

102
No

2
14

-
-

103
Lr

2
14

-
1

104
Rf

2
14

2
-

105
Db

2
14

3
-

106
Sg

2
14

4
-

107
Bh

2
14

5
-

108
Hs

2
14

6
-

109
Mt

2
14

7
-

110
Ds

2
14

8
-

111
Rg

2
14

9
-

112
Cn

2
14
10

-

113
Nh

2
14
10

1

114
Fl

2
14
10

2

115
Mc

2
14
10

3

116
Lv

2
14
10

4

117
Ts

2
14
10

5

118
Og

2
14
10
6

Periodic table forms
Sets of elements
Elements
History
See also

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