Electron configuration is essential for comprehending an element's chemical properties and reactivity. It involves the distribution of electrons in an atom's orbitals, following the Aufbau principle, Hund's rule, and the Pauli exclusion principle. These rules dictate how electrons fill orbitals to minimize energy, with exceptions like chromium and copper. Spectroscopy and ionization energy experiments validate these configurations, crucial for predicting chemical behavior.
Show More
Electron configuration is the distribution of electrons in an atom's orbitals, which determines its chemical properties and reactivity
Orbitals and Sub-Shells
Electrons are arranged in shells and sub-shells around the nucleus, with each sub-shell having a characteristic shape and energy level
Principal Quantum Numbers
The shells are numbered by principal quantum numbers, and the energy of sub-shells increases in the order s < p < d < f
Rules for Electron Configuration
Specific rules, such as the Aufbau principle, Hund's rule, and the Pauli exclusion principle, guide the arrangement of electrons in an atom to minimize its energy
Orbital Notation
Orbital notation visually represents each orbital as a box and electrons as arrows to indicate their spin
Electron Configuration Notation
Electron configuration notation lists the occupied sub-shells and the number of electrons in each, using superscript numbers
Condensed Notation
A condensed form of electron configuration notation uses the noble gas preceding the element to represent the core electrons, followed by the valence electrons' configuration
The electron configuration of a neutral atom reflects its number of electrons, which equals its atomic number
Anions and Cations
Anions are formed by adding electrons, while cations are created by removing electrons, typically from the outermost shell
Order of Electron Removal in Cations
When forming cations, electrons from the 4s orbital are usually removed before those from the 3d orbital, despite being filled earlier according to the Aufbau principle
Some elements, such as chromium and copper, have electron configurations that differ from predicted patterns to achieve a more stable, lower-energy state
These techniques measure the energy absorbed or emitted when electrons transition between energy levels, providing distinct spectral lines that correspond to specific electron transitions
The ionization energy increases significantly when removing an electron from a closed shell, reflecting the stability associated with full sub-shells
Empirical evidence from experiments, such as spectroscopy and ionization energies, supports the theoretical framework of electron configuration
00
The arrangement of electrons in ______ around an atom's nucleus is essential for understanding an element's ______ properties and ______.
shells
chemical
reactivity
01
Electron shells are identified by ______ ______ numbers (e.g., n=1, 2, 3), and within these shells, sub-shells are ordered by increasing energy: ______ < ______ < ______ < ______.
principal quantum
s
p
d
f
02
Aufbau Principle
Electrons occupy lowest energy orbitals first.
