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# Electronic Configuration

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 Sub Topics The distribution of electrons in various shell, sub shells and orbitals in an atom of an element is known as its complete electronic configuration. The distribution of electrons in various sub-shells or orbitals of the valence shell of an atom is called valence shell configuration. The electronic configuration of an atom is written in terms of nlx notation, when l=0 (s-sub shell), 1 (p-sub shell), 2 (d-sub shell) and 3 (f-sub shell). In this notation the superscript x, written at the top if l indicates the number of electrons present in the sub shell, given by l, while n written to the left of l indicates the number of shell to which the sub shell denoted by l belongs.Electronic configuration is a means of stating which kinds of orbitals contain electrons and the numbers of electrons and the numbers of electrons in each kind of orbital of an atom. It is expressed by the number and letter representing each kind of orbital and superscript numbers telling how many electrons are in each sub level.

## Electron Configuration Definition

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What is Electronic Configuration?

Electronic configuration has to do with the order in which electrons fill energy levels in the atoms of the elements of the atomic periodic table.

An electronic configuration of an organic molecule is defined as a listing of the MOs that are occupied with electrons in the configuration. Thus an electron configuration tells us how the electrons are distributed among the available orbitals and also provides a description of the electronic distribution of a molecule from the knowledge of the spatial distribution of the orbitals.

## Valence Electron Configuration

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The valence electron configuration of an atom essentially defines its personality. This personality includes the atoms size its appetite for electrons and its willingness to associate with other atoms in chemical bonding.

One of the justifications for grouping elements as we do in the periodic table have the same number of valence electrons in the same shapes of orbitals. In general the number of valence electrons in the same shapes of orbitals.

In general the number of valence electrons of an atom equals its group number. In the old styles of numbering periodic tables the number of valence electrons equals the group number as long as the groups in a given part of the periodic table are consecutively numbered. The groups of f-block elements are not numbered at all in a conventional periodic table, so we must count over from La and Ac as "3" or Ce and Th as "4". Lu and Lr should be numbered as having three valence electrons.

## Ground State Electron Configuration

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The ground state configuration is defined as the configuration for which the orbitals that are occupied produce the state of lowest energy. All other electronic configurations correspond to electronically excited states.

Each element has a distinctive configuration of electrons in orbitals its electron configuration. The lowest energy state an atom can have is described as its ground state. The electron configuration of the ground state of atoms of any element is determined by applying the rules.

The ground state electron configuration for first 10 elements are listed below.

 S.No Element Atomic number Electronic configuration Number of electrons in each orbital 1 H 1 1s1 1222222222 12222222 111222 11122 1112 2 He 2 1s2 3 Li 3 1s22s1 4 Be 4 1s22s2 5 B 5 1s22s22p1 6 C 6 1s22s22p2 7 N 7 1s22s22p3 8 O 8 1s22s22p4 9 F 9 1s22s22p5 10 Ne 10 1s22s22p6

The Excited State Electron Configuration are that they must contain the same total number of electrons as the ground state, and no energy level, or sub level can have more than its maximum number of electrons.

## Periodic Table with Electron Configuration

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There is a close relation between electronic configuration and long form of periodic table.
1. Each successive period in periodic table is concerned with filling of next higher principle energy level.
2. It is observed that the number of elements in each period is twice the number of atomic orbitals being filled.
3. The sixth period (n=6) contains 32 elements and successive electrons enter 6s, 4f, 5d and 6p orbitals in that order.
4. Elements in the same vertical column or group have similar electronic configuration have the same number of electrons in outermost orbitals and similar properties.
5. The elements placed in the same group or family constitute a family of elements having similar properties.

The periodic table based on the blocks in the periodic table is given below.

## Electron Configuration Diagram

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The depiction of electron configuration is the orbital box diagram , but the most frequency method is spdf method. The electron configuration diagrams is shown below.

## Electron Configuration Rules

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Electrons occupy orbitals in a predictable pattern according to these three rules.
1. Orbitals of lowest energy fill first. (the Aufbau principle)
2. A maximum of two electrons (of opposite spin) may occupy a single orbital (the Pauli exclusion principle)
3. When more than one orbital of the same energy is empty each of these orbitals will first acquire one electron before any orbital acquires the second electron (Hund's rule)

## Electron configuration Chart

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Electron configuration is the shape of the electrons around the atom, that is which energy level and what kind of orbital it is in. The electron configuration list is given below.

 Atomic Number Name of element Symbol Group Electron Configuration Symbol, group/series/block and Comments 1 Hydrogen H 1 1s1 2 Helium He 18 1s2 Group 0/18 Noble Gas, 3 Lithium Li 1 [He] 2s1 s-block, Group 1 Alkali Metal, 4 Beryllium Be 2 [He] 2s2 s-block, Group 2 Alkaline Earth Metal, 5 Boron B 13 [He] 2s2 2p1 p-block, Group 3/13 6 Carbon C 14 [He] 2s2 2p2 p-block, Gp4/14, 7 Nitrogen N 15 [He] 2s2 2p3 p-block, Gp5/15, 8 Oxygen O 16 [He] 2s2 2p4 p-block, Gp6/16, 9 Fluorine F 17 [He] 2s2 2p5 p-block, G p7/17 Halogen, 10 Neon Ne 18 [He] 2s2 2p6 p-block, Gp 0/18 Noble Gas, 11 Sodium Na 1 [Ne] 3s1 Gp1 Alkali Metal, 12 Magnesium Mg 2 [Ne] 3s2 s-block, Gp2 Alkaline Earth Metal, 13 Aluminum Al 13 [Ne] 3s2 3p1 p-block, Gp3/13, 14 Silicon Si 14 [Ne] 3s2 3p2 p-block, Gp4/14, 15 Phosphorus P 15 [Ne] 3s2 3p3 p-block, Gp5/15, 16 Sulfur S 16 [Ne] 3s2 3p4 p-block, Gp6/16, 17 Chlorine Cl 17 [Ne] 3s2 3p5 p-block, Gp7/17 Halogen, 18 Argon Ar 18 [Ne] 3s2 3p6 p-block, Gp 0/18 Noble Gas, 19 Potassium K 1 [Ar] 4s1 s-block, Gp1 Alkali Metal, 20 Calcium Ca 2 [Ar] 4s2 s-block, Gp2 Alkaline Earth Metal, 21 Scandium Sc 3 [Ar] 3d1 4s2 3d block, not trueTransition Metal 22 Titanium Ti 4 [Ar] 3d2 4s2 3d block, a true Transition Metal 23 Vanadium V 5 [Ar] 3d3 4s2 3d block, a true Transition Metal 24 Chromium Cr 6 [Ar] 3d5 4s1 3d block, a true Transition Metal 25 Manganese Mn 7 [Ar] 3d5 4s2 3d block, a true Transition Metal 26 Iron Fe 8 [Ar] 3d6 4s2 3d block, a true Transition Metal 27 Cobalt Co 9 [Ar] 3d7 4s2 3d block, a true Transition Metal 28 Nickel Ni 10 [Ar] 3d8 4s2 3d block, a true Transition Metal 29 Copper Cu 11 [Ar] 3d10 4s1 3d block, a true Transition Metal 30 Zinc Zn 12 [Ar] 3d10 4s2 3d block, not true Transition Metal 31 Gallium Ga 13 [Ar] 3d10 4s2 4p1 p-block, Gp3/13, 32 Germanium Ge 14 [Ar] 3d10 4s2 4p2 p-block, Gp4/14, 33 Arsenic As 15 [Ar] 3d10 4s2 4p3 p-block, Gp5/15, 34 Selenium Se 16 [Ar] 3d10 4s2 4p4 p-block, Gp6/16, 35 Bromine Br 17 [Ar] 3d10 4s2 4p5 p-block, Gp7/17 Halogen, 36 Krypton Kr 18 [Ar] 3d10 4s2 4p6 p-block, Gp 0/18 Noble Gas, 37 Rubidium Rb 1 [Kr] 5s1 s-block, Gp1 Alkali Metal, 38 Strontium Sr 2 [Kr] 5s2 s-block, Gp2 Alkaline Earth Metal, 39 Yttrium Y 3 [Kr] 4d1 5s2 4d block, not true Transition Metal 40 Zirconium Zr 4 [Kr] 4d2 5s2 4d block, a true Transition Metal 41 Niobium Nb 5 [Kr] 4d4 5s1 4d block, a true Transition Metal 42 Molybdenum Mo 6 [Kr] 4d5 5s1 4d block, a true Transition Metal 43 Technetium Tc 7 [Kr] 4d5 5s2 4d block, a true Transition Metal 44 Ruthenium Ru 8 [Kr] 4d7 5s1 4d block, a true Transition Metal 45 Rhodium Rh 9 [Kr] 4d8 5s1 4d block, a true Transition Metal 46 Palladium Pd 10 [Kr] 4d10 4d block, a true Transition Metal 47 Silver Ag 11 [Kr] 4d10 5s1 4d block, a true Transition Metal 48 Cadmium Cd 12 [Kr] 4d10 5s2 4d block, a true Transition Metal 49 Indium In 13 [Kr] 4d10 5s2 5p1 p-block, Gp3/13, 50 Tin Sn 14 [Kr] 4d10 5s2 5p2 p-block, Gp4/14, 51 Antimony Sb 15 [Kr] 4d10 5s2 5p3 p-block, Gp5/14, 52 Tellurium Te 16 [Kr] 4d10 5s2 5p4 p-block, Gp6/16, 53 Iodine I 17 [Kr] 4d10 5s2 5p5 p-block, Gp7/17 Halogen, 54 Xenon Xe 18 [Kr] 4d10 5s2 5p6 p-block, Gp 0/18 Noble Gas, 55 Cesium Cs 1 [Xe] 6s1 s-block, Gp1 Alkali Metal, 56 Barium Ba 2 [Xe] 6s2 s-block, Gp2 Alkaline Earth Metal, 57 Lanthanum La 3 [Xe] 5d1 6s2 Start of 5d-bock and Lanthanide Series 58 Cerium Ce 101 [Xe] 4f1 5d1 6s2 1st of f-block in the Lanthanides Metals 59 Praseodymium Pr 101 [Xe] 4f3 6s2 f-block in the Lanthanides Metals 60 Neodymium Nd 101 [Xe] 4f4 6s2 f-block in the Lanthanides Metals 61 Promethium Pm 101 [Xe] 4f5 6s2 f-block in the Lanthanides Metals 62 Samarium Sm 101 [Xe] 4f6 6s2 f-block in the Lanthanides Metals 63 Europium Eu 101 [Xe] 4f7 6s2 f-block in the Lanthanides Metals 64 Gadolinium Gd 101 [Xe] 4f7 5d1 6s2 f-block in the Lanthanides Metals 65 Terbium Tb 101 [Xe] 4f9 6s2 f-block in the Lanthanides Metals 66 Dysprosium Dy 101 [Xe] 4f10 6s2 f-block in the Lanthanides Metals 67 Holmium Ho 101 [Xe] 4f11 6s2 f-block in the Lanthanides Metals 68 Erbium Er 101 [Xe] 4f12 6s2 f-block in the Lanthanides Metals 69 Thulium Tm 101 [Xe] 4f13 6s2 f-block in the Lanthanides Metals 70 Ytterbium Yb 101 [Xe] 4f14 6s2 f-block in the Lanthanides Metals 71 Lutetium Lu 101 [Xe] 4f14 5d1 6s2 f-block in the Lanthanides Metals 72 Hafnium Hf 4 [Xe] 4f14 5d2 6s2 d-block element 73 Tantalum Ta 5 [Xe] 4f14 5d3 6s2 d-block element 74 Tungsten W 6 [Xe] 4f14 5d4 6s2 d-block element 75 Rhenium Re 7 [Xe] 4f14 5d5 6s2 d-block element 76 Osmium Os 8 [Xe] 4f14 5d6 6s2 d-block element 77 Iridium Ir 9 [Xe] 4f14 5d7 6s2 d-block element 78 Platinum Pt 10 [Xe] 4f14 5d9 6s1 d-block element 79 Gold Au 11 [Xe] 4f14 5d10 6s1 d-block element 80 Mercury Hg 12 [Xe] 4f14 5d10 6s2 d-block element 81 Thallium TI 13 [Xe]4f14 5d10 6s2 6p1 p-block element 82 Lead Pb 14 [Xe]4f14 5d10 6s2 6p2 p-block element 83 Bismuth Bi 15 [Xe]4f14 5d10 6s2 6p3 p-block element 84 Polonium Po 16 [Xe]4f14 5d10 6s2 6p4 p-block element 85 Astatine At 17 [Xe]4f14 5d10 6s2 6p5 p-block element 86 Radon Rn 18 [Xe]4f14 5d10 6s2 6p6 p-block element 87 Francium Fr 1 [Rn] 7s1 s-block radioactive element from 1st group 88 Radium Ra 2 [Rn] 7s2 s-block radioactive element from 2nd group 89 Actinium Ac 3 [Rn] 6d1 7s2 d-block element , 1st element of actinide 90 Thorium Th 102 [Rn] 6d2 7s2 f-block element , actinide 91 Protactinium Pa 102 [Rn] 5f2 6d1 7s2 f-block element , actinide 92 Uranium U 102 [Rn] 5f3 6d1 7s2 f-block element , actinide 93 Neptunium Np 102 [Rn] 5f4 6d1 7s2 f-block element , actinide 94 Plutonium Pu 102 [Rn] 5f6 7s2 f-block element , actinide 95 Americium Am 102 [Rn] 5f7 7s2 f-block element , actinide 96 Curium Cm 102 [Rn] 5f7 6d1 7s2 f-block element , actinides 97 Berkelium Bk 102 [Rn] 5f97s2 f-block element , actinides 98 Californium Cf 102 [Rn] 5f107s2 f-block element , actinides 99 Einsteinium Es 102 [Rn] 5f117s2 f-block element , actinides 100 Fermium Fm 102 [Rn] 5f127s2 f-block element , actinides 101 Mendelevium Md 102 [Rn] 5f137s2 f-block element , actinides 102 Nobelium No 102 [Rn] 5f147s2 f-block element , actinides 103 Lawrencium Lr 102 [Rn] 5f146d17s2 f-block element , actinides 104 Rutherfordium Rf 4 [Rn] 5f146d27s2 Artificial radioactive element and the first transactinide element. 105 Dubnium Db 5 [Rn] 5f146d37s2 Artificial radioactive element 106 Seaborgium Sg 6 [Rn] 5f146d47s2 Artificial radioactive element that does not occur in nature 107 Bohrium Bh 7 [Rn] 5f146d57s2 Radioactive element 108 Hassium Hs 8 [Rn] 5f146d67s2 Radioactive element 109 Meitnerium Mt 9 [Rn]5f146d77s2 Radioactive element

## Reactivity Series

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The arrangements of metals in the order of reactivity are called reactivity series. In other words a series of elements ranked in order of reactivity also known as reactivity series. It also measures the readiness of the metals to give up electrons to form positive ions.

## Quantum Numbers

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The Schrodinger equation can be solved approximately for atoms with two or more electrons. There are many solutions for the wave functions $\psi$, each associated with a set of numbers called quantum numbers. It is required to completely describe a specific electron in a multi-electron atom.

## Hyperconjugation

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Hyperconjugation involves binding n atoms to a central atom using fewer than n electron pairs around the central atom. Hyperconjugation is an interaction between an empty p orbital with the adjacent C-H sigma bond. Hyperconjugation is referred to as no bond resonance. It is also defined as the delocalization involving sigma bond.

## Aufbau Principle

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Aufbau principle is used to determine the electron configuration of a particular atom, it is also called as "building up" principle. Electrons are placed into orbitals from lowest energy orbital to highest energy orbital. Aufbau is a German word which means building up or construction. This is the reason that this principle is also known as building up principle or the construction principle.

## Valence Electrons Periodic Table

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To predict the electronic configuration the location of the particular element in the periodic table must be known. To aid this valence electrons are defined in which valence electrons with the highest principle quantum number in an atom and any electrons as unfilled sub shell from a lower shell. The orbitals in which the valence electrons reside are called the valence orbitals.