全国科普教育基地特色科普活动的项目.ppt

才智在线淘宝 Electromagnetic Radiation and Energy Electromagnetic Radiation: Energy traveling through space Three Characteristics of Waves: Wavelength: (symbolized l) Distance between two consecutive peaks or troughs in a wave Frequency: (symbolized n) How many waves pass a given point per second Speed: (symbolized c) How fast a given peak moves through space Electromagnetic Radiation and Energy c = λ x ν c = speed of light = 2.9979 x 108 m/s ν = frequency (s-1 or Hz) λ = wavelength (m) Spectra Sunlight yields continuous spectrum Energized gaseous elements yield certain wavelengths Line emission spectrum Rydberg Why did gaseous atoms emit certain wavelengths? Didn’t find out why, but came up with an equation Rydberg equation N=3, red line N=4, green line N=5, blue line Lyman series n 1 to n = 1 UV (invisible) Balmer series n 2 to n = 2 Visible wavelengths The Bohr Model of the Atom Explained Rydberg Electron energy quantized Electron only occupies certain energy levels or orbitals If it didn’t, electron would crash into protons in nucleus As “n” increases energy becomes less negative Increases Only certain amts of E may be absorbed/emitted If electron in lowest possible energy level Ground state If electron in excited energy level Excited state One can calculate energy needed to raise H electron per atom from ground state (n=1) to first excited state (n=2) Bohr’s Model Explains emission spectrum of H Movement of electrons from one quantized energy level to a lower one gave distinct emission wavelengths Model only good for one electron system Atomic orbital The probability function that defines the distribution of electron density in space around the atomic nucleus. The s-orbital The simplest orbital The only orbital in the s-subshell Occurs in every principal energy level “s” stands for “sharp” The first energy level only houses this orbital Can house up to 2 electrons The p-orbitals Start in second principle energy level (n=2) There are three p-or