CHM 101 1st EditionLecture 14Lecture 13 OverviewI. Specific HeatII. CalorimetryLecture 14I. Electronic Structure of AtomsII. Quantized EnergyIII. Atomic SpectraIV. Bohr’s Model of the Hydrogen atomElectric Structure of Atoms- Atoms react due to interactions between their electrons - Electronic Structure – the arrangement of the electrons within the atomThe wave nature of light - Much of what we know about electronic structure of atoms comes from the interaction of electromagnetic radiation with matter- Electronic radiation – oscillating electronic and magnetic fields traveling through space atthe speed of light - Wavelength – distance between successive crests and troughs of a wave ( )ƛ- Frequency – the number of wavelengths that pass through a fixed point each second (ν)- Electromagnetic radiation travels at the speed of lightC = 3.00 x 108 m/s- Relationship between speed of light and wavelength and frequencyC = νƛC – constant C units: m/sWavelength – units m ( )ƛFrequency – units 1/s or s-1 (ν)Hertz Hz = 1/s- and ν have an inverse relationshipƛo waves with short wavelengths have high frequencies o waves with long wavelengths have low frequencies - the longer the wavelength the less energy- Calculate the wavelength in m of the radio station (106.7 MHz)o ν = 106.7 MHz x 10 6 Hz = 1.067 x 108 Hz1 MHz = c/v = ƛ 3.00 x 10 8 m/s = 2.81m 1.067 x 108 s-1Quantized Energy - some behavior of electromagnetic radiation cannot be explained by treating light only as a wave- in some cases electromagnetic radiation seemed to interact with matter in discrete “chunks” of energy- photon – single particle of light- energy of photon lighto E = hνo h – Planck’s constant = 6.63 x 10-34jsAtomic Spectra - when an element is vaporized and then thermally of electrically excited it emits light- when this emitted light passes through a prism it produces a line spectrumBohr’s Model of the H atomI. only orbits of defined energy and radii are permitted in the hydrogen atomII. an electron in a permitted orbit has a specific energy and will not radiate energy and will not spiral into the nucleusIII. Energy is emitted when an electron goes from a higher energy level to a lower level. Energy is absorbed when an electron goes from a lower energy level to a higher level- Principal Quantum number (n) indicates which energy level the electron occupies- Inner circle – ground state, n = 1- Energy of the electron increases as it moves farther from the nucleus Bohr’s Model explained- The energy of electrons is quantized. Electrons can only exist in certain energy levels- Energy gained or lost by an atom involves electrons moving between these energy levels - Limitations to the model of Ho It could only be used for atoms with one electrono Relies on a planetary model with electrons moving around the nucleus in circular