HYDROGEN BOHR MODEL SERIES

The Lyman series of lines arise from transitions between higher excited states and level _.

The Lyman series of lines in hydrogen’s emission spectrum are invisible to the human eye, but they can be detected photographically.Calculate the energy (J) and wavelength (nm) of the photon emitted by the 4?1 transition in a hydrogen atom.A certain photon has a wavelength of 550 nm.The visible region of the electromagnetic spectrum lies between the wavelengths of _ and _ nm.The wavelength of the photons emitted by the hydrogen atom may also be calculated using the Rydberg equation shown below. The Lyman series lines occur in the ultraviolet region, the Balmer are in the visible region, and the Paschen and Brackett are in the infrared. This produces photons of many different wavelengths (the discrete lines we observe in the hydrogen spectrum) in the visible and other regions of the electromagnetic spectrum. Moreover, a given hydrogen atom’s electron may undergo several transitions before it reaches the ground state, emitting several photons. Some transitions occur more frequently than do others.

Since the number of hydrogen atoms in the tube is very large, the subsequent dropping of electrons to lower-energy levels and the ground state produces all possible transitions. The electron may be promoted to different higher-energy levels in each hydrogen atom. In the gas discharge tube, a high-energy beam of electrons strike the ground state hydrogen atoms, promoting the electron in each atom to higher-energy levels. Transitions from excited states to the ground state ( n = 1) involve much larger energy changes than do transitions to level 2 ( n = 2). The energy difference between levels gets smaller as levels increase. This is shown in the equations below:Īn excited electron may return to the ground state ( n = 1) or to any other lower excited state. The emitted light’s color and wavelength (?) depend on the magnitude of the energy change (?) due to the transition from one energy level to another. Some of the possible transitions are shown below.

When an excited-state electron drops back to a lower-energy state, it releases potential energy in the form of light. When the atom absorbs energy, as it does when placed in an electrical discharge or flame, its electron moves to a higher allowed energy level and the atom is said to be in an “excited state.” In a hydrogen atom’s first excited state, n = 2 in its second, n = 3 and so on. In the normal hydrogen atom, the electron is in its “ground state” for which n = 1. Hence the minus sign in the above equation. Moving the electron to any of its lower allowed energy states within the atom results in a decrease in potential energy a release of energy and an energy level below zero, i.e., negative. This energy level represents the highest potential energy state. In setting up his model, Bohr designated zero energy as the point where the proton and electron are completely separated, level infinity. He departed from classical theory, however, by imposing a “quantum restriction” upon the condition that the electron could exist only in certain “allowed states.” The energy could have only those values given by the equation: He was able to express the electron’s energy in terms of its orbital radius in a purely classical treatment based on Coulomb’s law of electrostatic attraction. Bohr related the proton’s electrostatic attraction for the electron to the force due to the electron’s orbital motion. In Bohr’s model, a hydrogen atom consists of a central proton about which a single electron moves in fixed spherical orbits. Consequently, the Bohr model retains a place in chemistry courses, even though it cannot be applied to other atoms. However, it does contain important features (e.g., quantized energy states) that are incorporated in our current model of the atom, and it does account for the line positions in hydrogen’s emission spectrum, which is important for this experiment. Introductionīohr’s model of the atom explains hydrogen’s spectrum but does not satisfactorily explain atoms that have more than 1 electron and proton and is, therefore, not the currently accepted model for all atoms. To observe hydrogen’s emission spectrum and to verify that the Bohr model of the hydrogen atom accounts for the line positions in hydrogen’s emission spectrum.

Hydrogen bohr model