Definition and Importance of Electron Configuration
– Electron configuration is the distribution of electrons in atomic or molecular orbitals.
– It helps understand the structure of the periodic table of elements.
– It describes the chemical bonds that hold atoms together.
– It helps determine the chemical formulas of compounds.
– It explains the geometries of molecules.
– Knowledge of electron configuration helps explain the properties of lasers and semiconductors.
– Electron configuration is used in understanding the behavior of atoms in chemical reactions.
– It is important in fields such as materials science and quantum chemistry.
Shells and Subshells
– Shells are sets of allowed states that share the same principal quantum number.
– Each electron shell can accommodate a specific number of electrons.
– Subshells are sets of states defined by a common azimuthal quantum number.
– Each subshell has a maximum number of electrons it can hold.
– The number of electrons in each shell and subshell follows quantum mechanical equations.
Notation
– Physicists and chemists use a standard notation for electron configurations.
– The notation consists of atomic subshell labels with the number of electrons assigned to each subshell as a superscript.
– For atoms with many electrons, an abbreviated notation is used.
– The electron configuration can be visualized as core electrons and valence electrons.
– The valence electrons in the outermost shell determine the element’s chemistry.
Energy of Ground State and Excited States
– The energy associated with an electron is that of its orbital.
– The energy of a configuration is approximated as the sum of the energy of each electron.
– The ground state is the configuration with the lowest electronic energy.
– Excited states occur when electrons are promoted to higher energy orbitals.
– Atoms can move between configurations by absorbing or emitting energy.
History and Periodic Table
– Irving Langmuir proposed the concentric theory of atomic structure in 1919.
– Langmuir’s work was based on the contributions of other chemists and the development of the periodic table and Octet rule.
– Niels Bohr incorporated Langmuir’s model into his explanation of periodicity in the properties of elements.
– Bohr’s model of electron shells had some differences from the modern understanding.
– Richard Abegg described valence electrons in 1904.
– The periodic table is closely related to the atomic electron configuration of each element.
– Elements in the same group have similar electron configurations and chemical properties.
– The periodic table blocks represent the number of electrons needed to fill subshells.
– Helium is an exception to the block arrangement due to its full outer shell.
– Valence electrons determine the chemical properties of elements. Source: https://en.wikipedia.org/wiki/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, meaning that the 1s, 2s and 2p subshells are occupied by 2, 2 and 6 electrons respectively.
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.[citation needed]
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, and for understanding the chemical formulas of compounds and the geometries of molecules. In bulk materials, this same idea helps explain the peculiar properties of lasers and semiconductors.
