The Bohr radius, often denoted as "a₀," is a fundamental physical constant in quantum mechanics and atomic physics. It is named after the Danish physicist Niels Bohr, who made significant contributions to our understanding of atomic structure.
The Bohr radius represents the average distance between the nucleus and the electron in the lowest energy state (ground state) of a hydrogen atom, or a hydrogen-like ion with a single electron (e.g., helium ion with only one electron remaining). It is a key parameter in the Bohr model of the hydrogen atom.
The Bohr radius is defined as:
a₀ = (4πε₀ħ²) / (me²),
where:
When you calculate the Bohr radius using these constants, you get a value of approximately 5.29177210903 x 10⁻¹¹ meters, or about 0.5292 angstroms (Å).
The Bohr radius is a critical parameter in understanding the structure of atoms, particularly hydrogen-like atoms. It provides a basic scale for the size of atomic orbitals and helps in describing the energy levels of electrons in these atoms.
A "link" is a unit of length that is equivalent to 1/100th of a chain. In the United States customary system of measurement, one link is equal to 7.92 inches or 0.201168 meters. It is primarily used in surveying and land measurement.
Links are often used in conjunction with other surveying units like chains and rods to measure distances on land, especially for large plots or parcels of land. The term "link" is rarely used in everyday conversation or modern applications outside of surveying and related fields. Instead, more common units like feet, yards, or meters are used for measuring length in most contexts.