Bohr radius

Definition

The Bohr radius is the average distance between the proton and the electron in a hydrogen atom in its ground state. It is a fundamental physical constant denoted by $a_0$.

5 Must Know Facts For Your Next Test

1. The Bohr radius is approximately $5.29 \times 10^{-11}$ meters.
2. It is derived from the Bohr model of the hydrogen atom, which was proposed by Niels Bohr in 1913.
3. The formula for the Bohr radius is $a_0 = \frac{4 \pi \epsilon_0 \hbar^2}{m_e e^2}$, where $\epsilon_0$ is the vacuum permittivity, $\hbar$ is the reduced Planck's constant, $m_e$ is the electron mass, and $e$ is the elementary charge.
4. The Bohr radius sets a scale for atomic systems and serves as a natural length unit in atomic physics.
5. In higher energy states (excited states), the average distance between the proton and electron can be described as multiples of the Bohr radius.

Review Questions

• What fundamental physical constant represents the average distance between a proton and an electron in a hydrogen atom in its ground state?
• Approximately how many meters is one Bohr radius?
• What constants are used to derive the formula for calculating the Bohr radius?

Related terms

Hydrogen Atom: The simplest atom consisting of one proton and one electron.

Niels Bohr: A physicist who proposed a model of atomic structure that introduced quantized orbits for electrons.

Reduced Planck's Constant ($\hbar$): $\hbar$, or h-bar, represents Planck's constant divided by $2\pi$. It plays a crucial role in quantum mechanics.