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Electron Configuration

Electronic Configuration Formula of Elements

Electronic configuration or general electron configuration structure formula of atoms based on the arrangement of orbital energy levels for s, p, and d-block elements in the periodic table. Electron holds the key to the chemical world for learning properties and periodic table configuration in chemistry or chemical science. Therefore, the chemical properties like oxidizing reducing properties, oxidation number, ionization energy, electron affinity, calculation of shielding effect, the polarity of chemical bonds,  acids bases properties, etc. are better understood by the electronic configuration or electron arrangement formula of periodic table elements. A chemical reaction to reach equilibrium is the change of electron configuration of reactant and product atoms. Hence the organic and inorganic chemical reactions better understood by the electronic configuration structure of chemicals elements.

To find the electron configuration formula first we find the order of electronic energy levels of s, p, d, and f orbitals or sub-levels. For example, 3s orbital has lower energy than 3p orbitals which again lower energy than 3d level. The modern periodic table classification bases on properties and general electron or electronic configuration to form s, p, d, and f block chemical elements in the periodic table.

Electron or electronic configuration general formula and energy of atoms in periodic table elements

Electronic Configuration & Energy Levels

The hydrogen element contains only one electron in 1s hydrogen energy levels with electronic configuration 1s1. But difficult for readers to remember the electron energy levels diagram for many electronic configurations. Therefore, the trivial way but most convenient way to remember these electronic energy levels configuration provides in online colleges and school courses by above the orbital diagram.

  1. The different electron orbitals originating from the same electronic energy levels are written in the horizontal configuration.
  2. Now inclined parallel lines are drawn through the electronic orbitals according to the above picture. Filling up the different orbitals by the number of electrons will follow these lines configuration.

Therefore, according to above digram structure, configuration energy levels with electron particles constructued the following ordering of electronic orbitals like 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f…

Formula for Filling Orbitals and Electronic Configuration

The filling up electronic orbitals with electron around the nucleus of atoms takes place according to the certain configuration formulas which are given below,

  1. The maximum number of electrons in the main quantum shell = 2n2, where n = principal quantum number.
  2. The maximum number of the electron in sub-shell like s, p, d, and f orbitals = 2(2l+1). Where l = 0, 1, 2, 3 for s, p, d, f orbitals. Therefore, s, p, d, f energy levels have a maximum of 2, 6, 10, 14 electrons respectively.
  3. German scientist Aufbau expresses building up a principle for the electron configuration process in different electronic orbitals of atoms. Hence according to this principle, the electrons are filled up in order of energy. Therefore, the orbitals with the lowest energy filled up first while the highest energy orbital filled up in the end.
  4. The electron will tend to form maximum spin. Therefore, electrons with similar spin configuration first.
  5. According to Hund’s rule, electrons are filling in the orbital with maximum spin multiplicity.
  6. Spin pairing occurs only when vacant orbitals of similar energy are not available for occupation.

Electron Configuration and Periodic Table

Electron configuration formula uses to derive some basic properties like the electromagnetic spectrum, chemical bonding, electric polarization, dipole moment, hydrogen bonding, etc of atoms in the molecule.

Modern periodic table classification based on chemical behavior and electron configuration structure of chemical elements. Hence the electron configuration structure or formula of elements must be connected with the periodic table. Therefore, the configuration of the electron in the outermost electronic energy levels or s, p, d, f orbitals detects the arrangement of the elements in the periodic table.

Electron Configuration of s-block Elements

In these elements, electron enters the ns-orbitals and progressively filled with atomic number. Therefore, Group-1 and 2 belong to s-block elements in the periodic table with general electron configuration ns1→2, where n = number of electronic shell or the number of periods in which the element present.

Group-1 or IA Elements

Group-1 or IA in the periodic table contains seven elements like hydrogen, lithium, sodium, potassium, rubidium, cesium, and francium with the general electronic configuration of valence electron = ns1, where n = 1 to 7. Due to the presence of one electron in the outer electronic structure, they have very low ionization energy but very high electron affinity.

Atomic Number Name of the Elements Electronic configuration
1 Hydrogen (H) 1s1
3 Lithium (Li) 1s2 2s1
11 Sodium (Na) [Ne] 3s1
19 Potassium (K) [Ar] 4s1
37 Rubidium (Rb) [Kr] 5s1
55 Cesium (Cs) [Xe] 6s1
87 Francium (Fr) [Rn] 7s1

Group-2 or IIA Elements

The elements of Group-2 or IIA in the periodic table are Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba) and Radium (Ra) are the alkaline earth metal crystal lattice with general electronic configuration valence electron = ns2, where n = 1 to 6.

Atomic Number Name of the Elements Electronic configuration
4 Beryllium (Be) 1s2 2s2
12 Magnesium (Mg) [Ne] 3s2
20 Calcium (Ca) [Ar] 4s2
38 Strontium (Sr) [Kr] 5s2
56 Barium (Ba) [Xe] 6s2
88 Radium (Ra) [Rn] 7s2

Electronic Configuration of p-block Elements

The elements in which s-block are progressively filled by electron are called p-block in the periodic table but helium whose electronic configuration 1s2. Helium is a member of this block. p-block contains six groups from the group-13 or IIIA to group-18 or zero. Therefore, the electronic configuration formula to find the outer electron configuration of the p-block element  ns2 np1→6.

Group-13 or IIIA Elements

Group-13 or IIIA contains five elements, Boron (B), Aluminum (Al), Gallium (Ge), Indium (In), Thallium (Tl) with valence shell electron configuration nS2 nP1. Where the atomic number of boron, aluminum, gallium, indium, and thallium = 2, 13, 31, 49, 81 respectively.

Atomic Number Name of the Elements Electronic configuration
5 Boron (B) 1s2 2s2 2p1
13 Aluminum (Al) [Ne] 3s2 3p1
31 Galium (Ga) [Ar] 3d10 4s2 4p1
49 Indium (In) [Kr] 4d10 5s2 5p1
81 Thallium (Tl) [Xe] 4f14 5d10 6s2 6p1

Group-14 or IVA Elements

Carbon (C), Silicon (Si), Germanium (Ge), Tin (Sn), and Lead (Pb) in the periodic table belongs to group-14 or IVA with the general electronic configuration of the valence electron, ns2 np2, where n = 2 to 6.

Atomic Number Name of the Elements Electronic configuration
6 Carbon (C) 1s2 2s2 2p2
14 Silicon (Si) [Ne] 3s2 3p2
32 Germanium (Ge) [Ar] 3d10 4s2 4p2
50 Tin (Sn) [Kr] 4d10 5s2 5p2
82 Lead (Pb) [Xe] 4f14 5d10 6s2 6p2

Group-15 or VA Elements

The five elements of Group-15 or VA are Nitrogen (N), Phosphorus (P), Arsenic (As), Antimony (Sb), Bismuth (Bi) with the electronic configuration of valence electron ns2 np3, where n = 2 to 6.

Atomic Number Name of the Elements Electronic configuration
7 Nitrogen (N) 1s2 2s2 2p3
15 Phosphorus (P) [Ne] 3s2 3p3
33 Arsenic (As) [Ar] 3d10 4s2 4p3
51 Antimony (Sb) [Kr] 4d10 5s2 5p3
83 Bismuth (Bi) [Xe] 4f14 5d10 6s2 6p3

Group-16 or VIA Elements

Oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po) in the periodic table belong to group-16 or VIA with the general electronic configuration of valence electron ns2 np4, where n = 2 to 6.

Atomic Number Name of the Elements Electronic configuration
8 Oxygen (O) 1s2 2s2 2p4
16 Sulfur (S) [Ne] 3s2 3p4
34 Selenium (Se) [Ar] 3d10 4s2 4p4
52 Tellurium (Te) [Kr] 4d10 5s2 5p4
84 Polonium (Po) [Xe] 4f14 5d10 6s2 6p4

Group-17 or VIIA Elements

Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At) in the periodic table belong to group-17, or VIIA with the general electronic configuration of valence electron ns2 np5, where n = 2 to 6.

Atomic Number Name of the Elements Electronic configuration
9 Fluorine (F) 1s2 2s2 2p5
17 Chlorine (Cl) [Ne] 3s2 3p5
35 Bromine (Br) [Ar] 3d10 4s2 4p5
53 Iodine (I) [Kr] 4d10 5s2 5p5
85 Astatine (At) [Xe] 4f14 5d10 6s2 6p5

Group-18 or Zero-Group Elements

Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn) in the periodic table belong to group-18, or zero-group with the general electronic configuration of the valence electron of noble gases ns2 np6, where n = 1 to 6.

Atomic Number Name of the Elements Electronic configuration
2 Helium (He) 1s2
10 Neon (Ne) 1s2 2s2 2p6
18 Argon (Ar) [Ne] 3s2 3p6
36 Krypton (Kr) [Ar] 3d10 4s2 4p6
54 Xenon (Xe) [Kr] 4d10 5s2 5p6
86 Radon (Rn) [Xe] 4f14 5d10 6s2 6p6

Electron Configuration of d-block Elements

The elements in which the electron enters in (n -1)d orbital are called d-block elements. These are placed in the middle of the periodic table, between s and p-block elements due to their chemical behavior like boing point, melting by specific heat, density, ionization energy, bonding, etc. The general electronic configuration of valence electron of 3d, 4d, 5d, 6d elements represented as ns0,1,2 (n-1)d1→10. These elements are called transition elements configure four series corresponding to filling electron in 3d, 4d, 5d, and 6d orbitals.

Electronic Configuration of 3d Series

The first crystalline solid metal in the 3d-series or first transition series starts with scandium and ending with zinc. When the twenty-first electron goes to the next available higher energy 3d orbital, the five 3d subshells filling by ten electrons.

Therefore, the general electronic configuration of valence electron of 3d series like Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn) is [Ar] 4S1→2 3d1→10.

Atomic Number Name of the Elements Electronic configuration
21 Scandium (Sc) [Ar] 4s2 3d1
22 Titanium (Ti) [Ar] 4s2 3d2
23 Vanadium (V) [Ar] 4s2 3d3
24 Chromium (Cr) [Ar] 4s1 3d5
25 Manganese (Mn) [Ar] 4s2 3d5
26 Iron (Fe) [Ar] 4s2 3d6
27 Cobalt (Co) [Ar] 4s2 3d7
28 Nickel (Ni) [Ar] 4s2 3d8
29 Copper (Cu) [Ar] 4s1 3d10
30 Zinc (Zn) [Ar] 4s1 3d10

In learning chemistry, chromium, and copper, the 3d elements of our environment reveal their general form of electron or electronic structure trends in the periodic table. Hence the general electronic configuration valence electron of chromium and copper are [Ar]4s2 3d4 and [Ar] 4s2 3d9.

In the periodic table elements, half-filled and filled orbitals electron structure or formula is relatively more stable than the partially filled orbitals. Thus 3d orbital of chromium and copper recording to form new electronic configuration to gain extra chemical stability by exchange energy.