Cobalt Noble Gas Shortcut Electron Configurations

The noble gas configuration is a shorthand electron configuration for atoms.

In chemistry, the noble gas configuration is a shorthand method of writing an atom's electron configuration. The reason for using the noble gas configuration is because the full electron configuration becomes very long for atoms with high atomic numbers.

Here is a look at how to write a noble gas configuration and a list of the electron configurations for all 118 elements.

How to Write a Noble Gas Configuration

The noble gas configuration gives the noble gas core that occurs before the element on the periodic table and then the electron configuration of the atom's valence electrons. But, you need to understand how to write the full electron configuration to find the number of valence electrons.

Here are the steps for writing a noble gas configuration:

Applying the Aufbau principle makes writing electron configurations much simpler.

1. Find the number of electrons for the atom. For a neutral atom, this is the same as the atomic number. (For an ion, the number of electrons is not the same as the number of protons, but otherwise the same steps apply.)
2. Fill in the electron shells and energy levels with the electrons.

   Each s shell holds up to 2 electrons.
   Each p shell holds up to 6 electrons.
   Each d shell holds up to 10 electrons.
   Each f shell holds up to 14 electrons.

3. Follow the Aufbau rule and write the full electron configuration. The Aufbau principle states that electrons fill lower energy levels before adding to higher energy levels. While you can use brute force to write the configuration, it's easier to draw a diagram and follow the diagonal:

   1s
   2s 2p
   3s 3p 3d
   4s 4p 4d 4f
   5s 5p 5d 5f
   6s 6p 6d
   7s 7p
   8s

   Notice the orbits overlap, so you don't just fill the shells sequentially (1, 2, 3, 4, …). Instead, use Madelung's rule:

   1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p

   Note: Madelung's rule is not a hard-and-fast rule, especially where some of the heavier transition metals are concerned. Relativistic effects come into play and change the order.

4. Find the noble gas preceding the element on the periodic table. Write the noble gas configuration by writing the noble gas core, followed by the valence electrons. A noble gas core is the noble gas element symbol enclosed in brackets: [He], [Ne], [Ar], [Kr], [Xe], or [Rn]. The valence electrons are "leftover" electrons that don't fill a shell or satisfy the octet rule (except for noble gases) or 18-electron rule (transition metals). There are two easy ways to identify them. Valence electrons are the electrons leftover past the noble gas electron configuration. They are also characteristic of an element group. For example, the alkali metals always have 1 valence electron.

Noble Gas Configuration Examples

For example, write the noble gas configuration of sodium.

• The atomic number of sodium is 11, so you know the neutral atom has 11 protons and also 11 electrons.
• Filling in the electron shells using the Aufbau principle gives a configuration of 1s² 2s² sp⁶ 3s¹. Add up the superscripts and double-check to make sure you have the correct number of electrons.
• Write the noble gas configuration. Looking at a periodic table, note the noble gas before sodium is neon. The electron configuration of neon is 1s² 2s² 2p⁶. So, the noble gas core symbol [Ne] replaces that portion of the sodium electron configuration. The noble gas configuration for sodium is [Ne] 3s¹.

For example, write the noble gas configuration of neon.

• Neon is a noble gas, but you can do better than just write [Ne] and call it good. First, use the periodic table and see the number of electrons for a neon atom is 10.
• Follow the Aufbau principle and fill electron shells: 1s² 2s² 2p⁶
• Write the noble gas configuration using the noble gas core before neon on the periodic table, followed by the valence electrons. The noble gas configuration of neon is [He] 2s² 2p⁶. Notice the valence of neon is 8 (2 electrons in the 2s shell and 6 electrons in the 2p shell), which indicates it has a filled octet.

List of Noble Gas Configurations for All 118 Elements

NUMBER	ELEMENT	ELECTRON CONFIGURATION
1	Hydrogen	1s1
2	Helium	1s2
3	Lithium	[He]2s1
4	Beryllium	[He]2s2
5	Boron	[He]2s22p1
6	Carbon	[He]2s22p2
7	Nitrogen	[He]2s22p3
8	Oxygen	[He]2s22p4
9	Fluorine	[He]2s22p5
10	Neon	[He]2s22p6
11	Sodium	[Ne]3s1
12	Magnesium	[Ne]3s2
13	Aluminum	[Ne]3s23p1
14	Silicon	[Ne]3s23p2
15	Phosphorus	[Ne]3s23p3
16	Sulfur	[Ne]3s23p4
17	Chlorine	[Ne]3s23p5
18	Argon	[Ne]3s23p6
19	Potassium	[Ar]4s1
20	Calcium	[Ar]4s2
21	Scandium	[Ar]3d14s2
22	Titanium	[Ar]3d24s2
23	Vanadium	[Ar]3d34s2
24	Chromium	[Ar]3d54s1
25	Manganese	[Ar]3d54s2
26	Iron	[Ar]3d64s2
27	Cobalt	[Ar]3d74s2
28	Nickel	[Ar]3d84s2
29	Copper	[Ar]3d104s1
30	Zinc	[Ar]3d104s2
31	Gallium	[Ar]3d104s24p1
32	Germanium	[Ar]3d104s24p2
33	Arsenic	[Ar]3d104s24p3
34	Selenium	[Ar]3d104s24p4
35	Bromine	[Ar]3d104s24p5
36	Krypton	[Ar]3d104s24p6
37	Rubidium	[Kr]5s1
38	Strontium	[Kr]5s2
39	Yttrium	[Kr]4d15s2
40	Zirconium	[Kr]4d25s2
41	Niobium	[Kr]4d45s1
42	Molybdenum	[Kr]4d55s1
43	Technetium	[Kr]4d55s2
44	Ruthenium	[Kr]4d75s1
45	Rhodium	[Kr]4d85s1
46	Palladium	[Kr]4d10
47	Silver	[Kr]4d105s1
48	Cadmium	[Kr]4d105s2
49	Indium	[Kr]4d105s25p1
50	Tin	[Kr]4d105s25p2
51	Antimony	[Kr]4d105s25p3
52	Tellurium	[Kr]4d105s25p4
53	Iodine	[Kr]4d105s25p5
54	Xenon	[Kr]4d105s25p6
55	Cesium	[Xe]6s1
56	Barium	[Xe]6s2
57	Lanthanum	[Xe]5d16s2
58	Cerium	[Xe]4f15d16s2
59	Praseodymium	[Xe]4f36s2
60	Neodymium	[Xe]4f46s2
61	Promethium	[Xe]4f56s2
62	Samarium	[Xe]4f66s2
63	Europium	[Xe]4f76s2
64	Gadolinium	[Xe]4f75d16s2
65	Terbium	[Xe]4f96s2
66	Dysprosium	[Xe]4f106s2
67	Holmium	[Xe]4f116s2
68	Erbium	[Xe]4f126s2
69	Thulium	[Xe]4f136s2
70	Ytterbium	[Xe]4f146s2
71	Lutetium	[Xe]4f145d16s2
72	Hafnium	[Xe]4f145d26s2
73	Tantalum	[Xe]4f145d36s2
74	Tungsten	[Xe]4f145d46s2
75	Rhenium	[Xe]4f145d56s2
76	Osmium	[Xe]4f145d66s2
77	Iridium	[Xe]4f145d76s2
78	Platinum	[Xe]4f145d96s1
79	Gold	[Xe]4f145d106s1
80	Mercury	[Xe]4f145d106s2
81	Thallium	[Xe]4f145d106s26p1
82	Lead	[Xe]4f145d106s26p2
83	Bismuth	[Xe]4f145d106s26p3
84	Polonium	[Xe]4f145d106s26p4
85	Astatine	[Xe]4f145d106s26p5
86	Radon	[Xe]4f145d106s26p6
87	Francium	[Rn]7s1
88	Radium	[Rn]7s2
89	Actinium	[Rn]6d17s2
90	Thorium	[Rn]6d27s2
91	Protactinium	[Rn]5f26d17s2
92	Uranium	[Rn]5f36d17s2
93	Neptunium	[Rn]5f46d17s2
94	Plutonium	[Rn]5f67s2
95	Americium	[Rn]5f77s2
96	Curium	[Rn]5f76d17s2
97	Berkelium	[Rn]5f97s2
98	Californium	[Rn]5f107s2
99	Einsteinium	[Rn]5f117s2
100	Fermium	[Rn]5f127s2
101	Mendelevium	[Rn]5f137s2
102	Nobelium	[Rn]5f147s2
103	Lawrencium	[Rn]5f147s27p1
104	Rutherfordium	[Rn]5f146d27s2
105	Dubnium	*[Rn]5f146d37s2
106	Seaborgium	*[Rn]5f146d47s2
107	Bohrium	*[Rn]5f146d57s2
108	Hassium	*[Rn]5f146d67s2
109	Meitnerium	*[Rn]5f146d77s2
110	Darmstadtium	*[Rn]5f146d97s1
111	Roentgenium	*[Rn]5f146d107s1
112	Copernium	*[Rn]5f146d107s2
113	Nihonium	*[Rn]5f146d107s27p1
114	Flerovium	*[Rn]5f146d107s27p2
115	Moscovium	*[Rn]5f146d107s27p3
116	Livermorium	*[Rn]5f146d107s27p4
117	Tennessine	*[Rn]5f146d107s27p5
118	Oganesson	*[Rn]5f146d107s27p6

Noble gas configurations with * are predicted values.

References

• Dzikowski, K. D.; et al. (2021). "Relativistic effective charge model of a multi-electron atom". Journal of Physics B: Atomic, Molecular and Optical Physics 54 (11): 115002. doi:10.1088/1361-6455/abdaca
• Langmuir, Irving (June 1919). "The Arrangement of Electrons in Atoms and Molecules". Journal of the American Chemical Society. 41 (6): 868–934. doi:10.1021/ja02227a002
• Rayner-Canham, Geoff; Overton, Tina (2014). Descriptive Inorganic Chemistry (6th ed.). Macmillan Education. ISBN 978-1-319-15411-0.
• Stoner, E.C. (1924). "The distribution of electrons among atomic levels". Philosophical Magazine. 6th Series. 48 (286): 719–36. doi:10.1080/14786442408634535
• Wong, D. Pan (1979). "Theoretical justification of Madelung's rule". Journal of Chemical Education. 56 (11): 714–18. doi:10.1021/ed056p714

Cobalt Noble Gas Shortcut Electron Configurations

Source: https://sciencenotes.org/noble-gas-configuration-shorthand-electron-configuration/

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