atomsurrounded

Atomsurrounded is a descriptive term used to refer to the immediate atomic environment of a given atom within a molecule, crystal, or material. It is not a widely standardized term in formal chemistry or physics, but appears in educational and explanatory contexts to emphasize the local surroundings that influence an atom's properties.

The concept focuses on the surrounding atoms, ligands, solvent molecules, and the electronic effects produced by this neighborhood. Key attributes include the coordination number, types of bonds (ionic, covalent, metallic), bond lengths and angles, local symmetry, and the presence of defects or distortions. The surrounding environment affects properties such as reactivity, spectroscopy, and catalytic activity.

In practice, atomsurrounded is analyzed using experimental and computational methods: X-ray crystallography and neutron diffraction reveal positions of neighboring atoms; extended X-ray absorption fine structure (EXAFS) and solid-state NMR probe local environments; electron microscopy can visualize local structure; and simulations like density functional theory and molecular dynamics model the electronic and geometric surroundings. Radial distribution functions and coordination-number analyses quantify the degree of surrounding.

Examples include a metal atom in a crystal lattice surrounded by nearest neighbors in the lattice, a transition-metal ion in a coordination complex surrounded by ligands, or a solvent-solvated ion where solvent molecules form the first solvation shell around the ion. The term helps convey how the local environment shapes observable properties.

See also: coordination number, local atomic environment, solvation shell, crystal field theory, radial distribution function.