It quantitatively explains the emission and absorption line spectrums of hydrogen and hydrogen-like atoms.Įach spectral line in absorption or emission spectrum can be associated to transition of states by the electron of a particular hydrogen atom.īohr's model also shows that the intensity of each spectral line depends upon the frequency or wavelength of photons absorbed or emitted. The energies of the stationary states of hydrogen-like ions are given by the expressionĪccording to Bohr's model, electrons are held in orbits by virtue of an electrostatic force, so that doesn't fall into the nucleus. Where n is the principal quantum number of the orbit and R H is Rydberg's constantīohr's theory also applies to other hydrogen-like ions, such as He ⁺, Li ⁺² and Be. The energy of a stationary state or orbit is given by the equation An electron moving in a circular orbit has an angular momentum equal to the product of its mass (m e ), linear velocity (v) and radius of orbit (r), which can be expressed as The frequency of the radiation emitted or absorbed can be represented by the equation,Ĥ. The energy gap between the two orbits is given by equationģ. So each emission or absorption of radiation energy represents the electron transition from one stationery orbit to another. ![]() The energy of an electron in the orbit remains constant until the electron absorbs energy to jump to a higher orbit or releases energy to move to a lower orbit. Electrons are held in orbits by an electrostatic force.Ģ. The electron in the hydrogen atom can move around the nucleus in circular paths of fixed radius and energy called orbits also called stationary states. It was based on the four postulates - Motion of electrons in an orbit, Fixed Energy of electrons, Transition of orbits by electrons, and Angular momentum of electrons.ġ. (They are the same movies as on your CD, animations 8.In 1913, Neils Bohr proposed an atomic model that quantitatively explained the structure of hydrogen atom and its spectrum. Please look on your CD for animations regarding absorbsion and emission or go Light photons emitted are listed on the right side, with the arrow showing the The energy levels (n) are listed on the left side, followed by Shows the various energies and the corresponding transitions.Īn energy level diagram for a hydrogen atom, notĭrawn to scale. The red line comes an electron going from 3 to 2. Moving from a higher energy orbit to a lower energy orbit, it emits a photon ofĪ specific frequency and energy value. Each time an electron males a "quantum leap," While you are there, notice that each of the elements has a different patternĬan use this to analyze what some matter is made of? YES! Red absorption line comes from an electron absorbing that wavelength and going When a broad visible spectrum of light shines on hydrogen, notice it only Look at the following applet and start with hydrogen. Is because the electrons can only be in these distinct orbitals. This explains why hydrogen absorbs only specific wavelengths of light and Transitions to 2 (3 to 2, 4 to 2, 5 to 2 etc) are in the visible region. The transitions to 1 (2 to 1, 3 to 1, 4 to 1 etc) are all in the UV region This experiment it is excited into a higher orbit by the electrical energy (sayīack to a more stable orbit it can release the energy as light of a specific The electron is normally in the lowest orbit (orbit number 1) which That the energies of the electrons are quantized. ![]() By saying that the electron can only have specific energies, we can say The energy of the orbits increases as you get further from the nucleus. What Bohr said was that the electron could only exist in these blue orbits,ĭefinite energy with the inner orbit being the lowest in energy. I have drawn 4 orbits but there are more. An electron in an atom can only exist in certain orbits around the Stated that the electrons orbit the nucleus the way the earth orbits the sun. Wall socket and convert that to radiant or light energy. The lamps get there energy from the electrical potential energy of the Produces a line spectrum that contains only certain frequencies. This does not surprise us as we remember that white light is aĪn interesting thing happens when we use light just from one element, such as Into a spectrum from red (lowest energy) to violet (highest energy). Through a thin slit and then through a prism, the prism will separate the colors Bohr model of hydrogen atom postulates An atom or hydrogen atom possesses several stable circular orbitals in which an electron can stay. ![]() Atomic Spectra and the Bohr Model Atomic Spectra and the Bohr Modelįrom incandescent solids, liquids, or dense gases, produces a continuous
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