Development of Modern Atomic theory

Modern Model of Atom When energy is added to an atom : Low NRG State (ground state)  High energy state (excited state) Upon return to ground state, the atom gives off the energy it gained by emitting EMR—LIGHT!

Line-Emission Spectrum (Bright Line Spectrum) When light emitted by excited atoms is passed through a prism, separated into a series of bands of specific frequencies (and therefore wavelengths) This pattern of bands is known as a line emission or bright line spectrum Like a fingerprint for an element—each element has its own distinct banding pattern

Hydrogen’s BLS Explained by Bohr Linked electrons with the photon emission(BLS) of the atom Stated that electrons can only exist in orbits with specific energies—fixed paths Electron can jump from orbit to higher energy orbit (excited state) when energy is added When e - drops back down, emits photon Amount of energy photon=energy difference between the two orbits E=hv

Bohr

Energy Level diagram for hydrogen

Balmer series Hydrogen BLS

Bohr Summary- 5 parts 1. The electron travels in a circular path around nucleus called an orbit

Bohr summary 2. Electron exists in normal conditions in it low energy state called a ground state

Bohr Summary 3. When energy added to electron, it moves to new orbit farther from the nucleus, which is a position of higher energy content. This is called the excited state

Bohr Summary 4. When an electron moves from one orbit to another, it does so without ever passing through the space between orbits ”Quantum jump” —IT IS ONLY ALLOWED AT VERY SPECIFIC DISTANCES FROM NUCLEUS

Bohr Summary 5. When the electron drops from excited state back to a low energy state, and ultimately to ground state, it is accompanied by a simultaneous release of energy in the form of EMR (photon). The energy of the EMR corresponds to the energy differnce between the two orbits

Bohr’s Problems Theory only explained behavior of Hydrogen’s electron Violates Heisenberg’s Uncertainty principle- claimed to know exactly where an electron is and what it was doing.