Electron Configuration - Meaning, Definition, Rules, Table, FAQs

Q: What is copper's electronic configuration?

Copper has the electronic configuration of atoms[Ar]3d 10 4s 1 . Due to the narrow energy gap between the 3d and 4s orbitals, this electronic structure violates the aufbau principle. The fully filled d-orbital arrangement is more stable than the partially filled one.

Edited By Team Careers360 | Updated on Jul 02, 2025 04:31 PM IST

What is Electronic Configuration?

Electron configuration definition and electron configuration meaning: An atom's electron configuration is a depiction of the distribution of electrons among the orbital shells and subshells. The electronic configuration of elements is commonly used to describe an atom's orbitals in its ground state, but it may also be used to depict an atom that has ionised into a cation or anion by compensating for electron loss or gain in succeeding orbitals. Many of an element's physical and chemical features can be linked to its unique electron configuration. The distinctive chemistry of the element is determined by the valence electrons, which are electrons in the outermost shell.

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What is Electronic Configuration?
Electron configuration periodic table:
Energy levels:
Rules for filling orbitals in Electron Configuration Chart:
Hydrogen electron configuration:
Oxygen electron configuration:

The electrons, on the other hand, are those that exist beyond the nucleus of the atom, and their precise distribution within the atom is crucial in directing the chemical reactions that the atom is involved in. The precise distribution of electrons in an atom is defined by its electronic configuration of all elements, and this distribution aids in understanding the reasons for chemical events that the atom or its associated molecules are involved in.

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Electron configuration periodic table:

The elements are organised into columns based on their atomic number (number of protons in the nucleus). Elements with comparable chemical characteristics are grouped together. The periodic table's form resembles the filling of subshells with electrons. The s subshells are occupied in the first two columns on the left side of the periodic table. Similarly, the p block represents the periodic table's right-most six columns, the d block represents the periodic table's middle ten columns, and the f block represents the 14-column area that is generally shown as separate from the main body of the periodic table.

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Electron Configuration Table

Energy levels:

Energy levels are defined as fixed distances in which electrons rotate around the nucleus with a defined amount of energy. With increasing distance from the nucleus, the energy associated with a given energy level rises. In 1s hydrogen energy levels with electronic configuration formula 1s1, the hydrogen electron configuration atom has only one electron. However, readers may find it challenging to recall the electron energy levels diagram for many electrical combinations.

Shell and ‘n’ value	Max. electron in electron configuration
K shell, n=1	2×2¹=2
L shell, n=2	2×2²=8
M shell, n=3	2×2³=16
N shell, n=4	2×2⁴=32

The placement of electrons in electron orbitals around the nucleus of atoms follows a set of laws. 2n², where n is the major quantum number, is the maximum number of electrons in the main energy levels. The maximum number of electrons in subshell orbitals such as the s, p, d, and f orbitals = 2(2l+ 1). For the s, p, d, and f orbitals, l = 0, 1, 2, 3. Where l is the azimuthal quantum number. As a result, the s, p, d, and f energy levels each have a maximum of 2, 6, 10, and 14 electrons.

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Principle Quantum number value	Value of Azimuthal quantum Number (l)	Subshell
n=1	l=0	1s
n=2	l=0 l=1	2s 2p
n=3	l=0 l=1 l=2	3s 3p 3d
n=4	l=0 l=1 l=2 l=3	4s 4p 4d 4f

Notation: Subshell labels are used to represent an atom's electron arrangement. The shell number (determined by the primary quantum number), the subshell name (determined by the azimuthal quantum number), and the total number of electrons in the subshell are all listed in superscript on these labels. For instance, if two electrons are occupied in the first shell's's' subshell, the resultant notation is '1s2.'The electron configuration of magnesium (atomic number 12) can be expressed as 1s² 2s² 2p⁶ 3s² using these subshell labels.

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Rules for filling orbitals in Electron Configuration Chart:

Aufbau Rule: The term "Aufbeen" comes from the German word "aufbauen," which means "to build up." According to the Aufbau principle, electrons will first occupy lower-energy orbitals before moving on to higher-energy orbitals. The sum of the primary and azimuthal quantum numbers is used to compute the energy of an orbital. Electrons are filled in the following order according to this principle: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.

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It's worth noting that the Aufbau principle has many exceptions, such as chromium and copper. The stability afforded by half-full or entirely filled subshell electronic configurations can occasionally explain these exceptions.

Pauli exclusion principle: According to the Pauli exclusion principle, an orbital can only hold a maximum of two electrons with opposite spins. “No two electrons in the same atom have the same values for all four quantum numbers,” says this principle. As a result, if two electrons have the same primary, azimuthal, and magnetic numbers, they must have opposite spins.

Hund’s Rule: This rule specifies the order in which electrons are filled in all of a subshell's orbitals. It asserts that before a second electron is inserted in an orbital, every orbital in a particular subshell is single-occupied by electrons. The electrons in orbitals with only one electron have the same spin in order to maximise the total spin (or the same values of the spin quantum number).

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Example: the electronic configuration is 1s²2s²2p³, it can be represented using hund’s rule as:

Hund's Rule

Hydrogen electron configuration:

Hydrogen has an atomic number of one. As a result, a hydrogen atom has one electron, which will be placed in the first shell's subshell. Hydrogen has a 1s1 electron configuration, as seen below.

Hydrogen

Oxygen electron configuration:

The atomic number of oxygen is 8, which means it has eight electrons. The following is the order in which its electrons are filled:

2 electrons in the K shell

6 electrons in the L shell

As a result, the electron configuration of oxygen is 1s²2s²2p⁴, as illustrated in the diagram below.

Oxygen

NCERT Chemistry Notes :

Noble gas electron configuration:

Element	Electronic configuration
Helium	1s²
Neon	[He]2s²2p⁶
Argon	[Ne]3s²3p⁶
Krypton	[Ar]3d¹⁰4s²4p⁶
Xenon	[Kr]4d¹⁰5s²5p⁶
Radon	[Xe]4f¹⁴5d¹⁰6s²6p⁶
Oganesson	[Rn]5f¹⁴6d¹⁰7s²7p⁶

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Frequently Asked Questions (FAQs)

1. What is copper's electronic configuration?

Copper has the electronic configuration of atoms[Ar]3d¹⁰4s¹. Due to the narrow energy gap between the 3d and 4s orbitals, this electronic structure violates the aufbau principle. The fully filled d-orbital arrangement is more stable than the partially filled one.

2. What is the electron configuration of spdf?

These are the orbitals which tells us about the order and number of electrons in each shell. The maximum number of electrons that can fill in these orbitals are:

s: 1 orbital, 2 electrons.

p: 3 orbitals, 6 electrons.

d: 5 orbitals, 10 electrons.

f: 7 orbitals, 14 electrons.

3. How to find valence electrons from electron configuration?

The electron configuration of an atom can be used to calculate the number of valence electrons present. The orbitals associated with an atom's highest occupied energy level include valence electrons. The remaining electrons, known as inner shell electrons, aren't involved in bonding. Example- the electronic configuration of sulphur is :

S=1s²2s²2p⁶3s²3p⁴Sulphur has its electrons in 3 energy levels, valence electrons are the outermost electron thus found in the highest energy shell occupied. As a result, only electrons associated with an energy level/orbital combination that starts with a 3 must be examined in this scenario. Both orbitals are chosen for further analysis because two energy level/orbital pairings begin with a 3:

3s²3p⁴

There are a total of six superscripts linked with these orbitals. Sulfur contains six valence electrons as a result.

4. What is the formula for electronic configuration?

Electronic Configuration is the dispersion of electrons in an atom. The formula 2n², where n=orbit number, aids in determining the maximum number of electrons present in an orbit. The formula is known as the "Bohr Bury Schemes," and it aids in the determination of electron configuration.

5. What is the significance of electronic configurations?

By assisting in the determination of an atom's valence electrons, electron configurations provide insight into the chemical behaviour of elements. It also aids in the classification of elements into separate blocks (such as the s-block elements, the p-block elements, the d-block elements, and the f-block elements). This makes it easy to investigate the properties of the components as a group.

6. How does the periodic table relate to electron configuration?

The periodic table is organized based on electron configuration. Elements in the same group (column) have similar outer electron configurations, while periods (rows) represent the filling of a new energy level.

7. How does electron configuration influence an element's position in the periodic table?

An element's position in the periodic table is determined by its electron configuration. The period number corresponds to the highest occupied energy level, while the group number is related to the number of valence electrons.

8. What are valence electrons and how do they relate to electron configuration?

Valence electrons are the electrons in the outermost shell of an atom. They are crucial for chemical bonding and reactivity. The electron configuration directly shows the number and arrangement of these valence electrons.

9. How do transition metals differ in their electron configuration?

Transition metals have partially filled d orbitals in their electron configuration. This results in unique properties such as multiple oxidation states, colored compounds, and catalytic activity.

10. What is the significance of noble gas configuration in writing electron configurations?

Noble gas configuration is a shorthand method for writing electron configurations. It uses the symbol of the previous noble gas in brackets, followed by the remaining electron configuration. This method is especially useful for elements with many electrons.

11. What is the difference between ground state and excited state electron configurations?

The ground state is the lowest energy configuration where electrons occupy the lowest available energy levels. An excited state occurs when an electron is promoted to a higher energy level, resulting in a less stable but more reactive configuration.

12. What are subshells in electron configuration?

Subshells are subdivisions of electron shells, represented by the letters s, p, d, and f. Each subshell has a specific shape and can hold a maximum number of electrons: s (2), p (6), d (10), and f (14).

13. What is the octet rule and how does it relate to electron configuration?

The octet rule states that atoms tend to gain, lose, or share electrons to achieve a full outer shell of eight electrons (like noble gases). This rule is based on the stability associated with filled s and p orbitals in the outermost energy level.

14. How does the concept of electron shielding affect electron configuration?

Electron shielding occurs when inner electrons partially shield outer electrons from the full attractive force of the nucleus. This affects the energy levels of orbitals and influences the order in which orbitals are filled.

15. What is the aufbau diagram and how is it used in electron configuration?

The aufbau diagram is a visual representation of the order in which orbitals are filled. It shows energy levels and sublevels, helping to determine the correct sequence for electron configuration (1s, 2s, 2p, 3s, 3p, 4s, 3d, etc.).

16. What is the relationship between electron configuration and photoelectron spectroscopy?

Photoelectron spectroscopy measures the binding energies of electrons, which are directly related to their arrangement in orbitals. The spectra obtained provide experimental evidence for electron configuration and energy levels.

17. How does electron configuration explain the formation of electron domains in VSEPR theory?

Electron configuration shows the number of valence electrons available for bonding and lone pairs. These electrons form electron domains around the central atom, determining molecular geometry according to VSEPR theory.

18. How does electron configuration explain the color of transition metal compounds?

The color of transition metal compounds is due to d-d transitions, where electrons in partially filled d orbitals absorb specific wavelengths of light. The electron configuration determines the energy differences between these d orbitals, resulting in characteristic colors.

19. How does electron configuration influence the magnetic properties of materials?

The electron configuration, particularly the presence of unpaired electrons, determines whether a material is diamagnetic, paramagnetic, or ferromagnetic. This influences how the material interacts with magnetic fields and its potential applications.

20. How does electron configuration relate to the concept of electronegativity?

Electronegativity is influenced by the effective nuclear charge and the distance of valence electrons from the nucleus, both of which are determined by electron configuration. Elements with nearly filled outer shells tend to have higher electronegativity.

21. How does electron configuration explain the formation of ions?

Electron configuration explains ion formation by showing how atoms gain or lose electrons to achieve a stable noble gas configuration. Metals tend to lose electrons to form cations, while non-metals gain electrons to form anions.

22. How does electron configuration explain the formation of chemical bonds?

Electron configuration shows the number and arrangement of valence electrons, which are involved in chemical bonding. Atoms share, transfer, or pool electrons to achieve stable configurations, forming covalent, ionic, or metallic bonds.

23. What is the difference between diamagnetic and paramagnetic elements based on electron configuration?

Diamagnetic elements have all paired electrons in their electron configuration, resulting in no net magnetic moment. Paramagnetic elements have one or more unpaired electrons, creating a net magnetic moment and attraction to magnetic fields.

24. How do you determine the number of unpaired electrons from an electron configuration?

To determine the number of unpaired electrons, look at the highest energy subshell in the configuration. Count the number of electrons that are alone in orbitals (following Hund's rule) before pairing occurs.

25. How does electron configuration relate to an element's spectral lines?

Spectral lines are produced when electrons move between energy levels. The electron configuration determines the possible energy transitions, which correspond to specific wavelengths of light emitted or absorbed, creating unique spectral patterns for each element.

26. What are the main principles governing electron configuration?

The main principles are the Aufbau principle (electrons fill orbitals from lowest to highest energy), Pauli exclusion principle (no two electrons in an atom can have the same four quantum numbers), and Hund's rule (electrons occupy orbitals of equal energy individually before pairing).

27. How does the Aufbau principle work in electron configuration?

The Aufbau principle states that electrons fill orbitals in order of increasing energy. This means they occupy the lowest energy orbitals first before moving to higher energy levels, following the order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, and so on.

28. What is the significance of the Pauli exclusion principle in electron configuration?

The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers. This principle limits the number of electrons that can occupy each orbital to a maximum of two, with opposite spins.

29. How does Hund's rule affect electron configuration?

Hund's rule states that electrons in orbitals of equal energy (such as p or d orbitals) will occupy separate orbitals before pairing up. This minimizes electron repulsion and results in a more stable configuration.

30. How do you write electron configuration using the spectroscopic notation?

Spectroscopic notation lists the orbitals in order of increasing energy, with the number of electrons in each orbital written as a superscript. For example, the electron configuration of carbon is 1s² 2s² 2p².

31. What is electron configuration?

Electron configuration is the arrangement of electrons in an atom's orbitals. It describes how electrons are distributed in various energy levels and sublevels around the nucleus, following specific rules and patterns.

32. Why is electron configuration important in chemistry?

Electron configuration is crucial because it determines an element's chemical properties, reactivity, and bonding behavior. It helps predict how atoms will interact with each other and form compounds.

33. What is the relationship between electron configuration and chemical reactivity?

Chemical reactivity is largely determined by valence electrons, which are shown in the electron configuration. Elements with similar outer electron configurations (same group) tend to have similar chemical properties and reactivity.

34. What is the significance of core electrons in electron configuration?

Core electrons are the inner electrons not involved in chemical bonding. While they don't participate directly in reactions, they influence the effective nuclear charge experienced by valence electrons, affecting an atom's size and ionization energy.

35. What is the connection between electron configuration and periodic trends?

Electron configuration directly influences periodic trends such as atomic radius, ionization energy, and electronegativity. These trends are explained by the number of energy levels, the number of valence electrons, and the effective nuclear charge.

36. What is the significance of the 18-electron rule in transition metal complexes?

The 18-electron rule states that stable transition metal complexes often have a total of 18 valence electrons (including those from ligands). This rule is based on filling all valence orbitals (s, p, and d) to achieve a noble gas-like configuration.

37. What is the significance of the lanthanide and actinide contractions in electron configuration?

The lanthanide and actinide contractions occur due to poor shielding by f electrons. This results in a decrease in atomic and ionic radii across these series, affecting the electron configurations and properties of subsequent elements.

38. What is the significance of the noble gas core in writing electron configurations?

The noble gas core notation simplifies writing electron configurations for larger atoms. It uses the symbol of the previous noble gas in brackets, followed by the remaining electron configuration, emphasizing the valence electrons most important for chemical behavior.

39. What causes exceptions to the expected electron configuration?

Exceptions occur due to the stability of half-filled or fully filled subshells. For example, chromium ([Ar]3d⁵4s¹) and copper ([Ar]3d¹⁰4s¹) have configurations that differ from what the aufbau principle would predict.

40. How does the concept of effective nuclear charge relate to electron configuration?

Effective nuclear charge is the net positive charge experienced by an electron, considering the shielding effect of inner electrons. It increases across a period as more protons are added, affecting the energy levels and filling order of orbitals.

41. How does spin-orbit coupling affect electron configuration in heavier elements?

Spin-orbit coupling is the interaction between an electron's spin and its orbital angular momentum. In heavier elements, this effect becomes significant, leading to splitting of energy levels and more complex electron configurations.

42. How does electron configuration explain the formation of coordination compounds?

Electron configuration of transition metals, particularly their partially filled d orbitals, allows them to accept electron pairs from ligands to form coordination compounds. The number and arrangement of d electrons influence the geometry and properties of these complexes.

43. How does electron configuration relate to the concept of hybridization?

Hybridization involves the mixing of atomic orbitals to form new hybrid orbitals. The electron configuration of an atom determines which orbitals are available for hybridization, influencing molecular geometry and bonding.

44. What is the relationship between electron configuration and molecular orbital theory?

Electron configuration provides the starting point for molecular orbital theory. The atomic orbitals described by electron configuration combine to form molecular orbitals, determining the bonding characteristics and properties of molecules.

45. What is the significance of the aufbau principle exceptions in the periodic table?

Exceptions to the aufbau principle, such as in chromium and copper, highlight the importance of stability gained from half-filled or fully filled subshells. These exceptions affect the chemical and physical properties of these elements and their compounds.

46. What is the significance of the Madelung rule in electron configuration?

The Madelung rule (also known as the n+l rule) determines the order of orbital filling based on the sum of the principal quantum number (n) and the azimuthal quantum number (l). This rule explains the observed patterns in electron configuration across the periodic table.

47. What is the connection between electron configuration and atomic emission spectra?

Atomic emission spectra result from electrons transitioning between energy levels. The electron configuration determines the possible transitions, producing unique spectral lines for each element, which are used in spectroscopic analysis and element identification.

48. How does electron configuration explain the formation of metallic bonds?

Metallic bonding occurs in elements with few valence electrons and many available orbitals, as seen in their electron configurations. This allows for the delocalization of valence electrons, forming an "electron sea" that holds the metal atoms together.

49. What is the significance of the Aufbau principle in understanding chemical periodicity?

The Aufbau principle explains the periodic repetition of chemical properties by showing how electron shells are filled. This principle underlies the organization of the periodic table and the similarities between elements in the same group.

50. How does electron configuration relate to the concept of electron affinity?

Electron affinity is the energy change when an atom gains an electron. It is influenced by the electron configuration, particularly the energy and occupancy of the outermost orbitals, and follows periodic trends based on atomic structure.

51. What is the relationship between electron configuration and atomic size?

Atomic size is determined by the number of electron shells and the effective nuclear charge, both of which are described by the electron configuration. Generally, atomic size increases down a group and decreases across a period due to these factors.

52. How does electron configuration explain the formation of molecular orbitals?

Molecular orbitals are formed by the combination of atomic orbitals from individual atoms. The electron configuration of each atom determines which orbitals are available for overlap, influencing the type and strength of bonds formed in molecules.

53. How does electron configuration relate to the concept of ionization energy?

Ionization energy is the energy required to remove an electron from an atom. It is directly related to the electron configuration, particularly the energy level and subshell of the outermost electrons, and follows periodic trends based on atomic structure.

54. What is the connection between electron configuration and the formation of crystal field splitting?

Crystal field splitting in transition metal complexes is influenced by the electron configuration of the metal ion. The distribution of electrons in d orbitals affects how these orbitals interact with ligands, determining the complex's geometry and properties.

55. How does electron configuration explain the difference between metals, nonmetals, and metalloids?

The electron configuration, particularly the number and arrangement of valence electrons, determines whether an element behaves as a metal, nonmetal, or metalloid. Metals have few valence electrons, nonmetals have nearly full valence shells, and metalloids have intermediate configurations, resulting in their unique properties.