Electrons “in Orbit” Topic 2.2

Know the following about the EM spectrum: The electromagnetic spectrum Know the following about the EM spectrum: visible, infrared, and UV regions describe the variation in: wavelength frequency energy colors for visible light Know what is in the red boxes

The Electromagnetic Spectrum High frequency Short wavelength High energy lower frequency longer wavelength lower energy

Continuous vs. Line Spectrum

continuous spectrum produced by light as it passes through a prism in the case of white light, all colors are seen there are no “levels”

emission line spectrum energy is applied to a specific element this “excites” the element and the light is viewed through a spectroscope a continuous spectrum is NOT observed, but a series of very bright lines of specific colors with black spaces in-between instead unique for every element and are used to identify atoms (much like fingerprints are used to identify people)

Give off energy when falls back down to a ground energy level More on emission line spectrum Give off energy when falls back down to a ground energy level

the process electrons surround the nucleus in specific orbitals or energy levels when electrons are excited (heat/electricity) they can move to a higher energy level when they move back down they emit energy in the form of electromagnetic radiation because electrons can only exist in certain energy levels, only certain transitions can occur the color of the light emitted depends on the frequency of the emitted photon http://www.youtube.com/watch?v=QI50GBUJ48s

this is a repetitive slide an electron in the atom gains (absorbs) energy from heating electron jumps up an energy level. electron is now unstable (unwelcome) in this level and is “kicked out” when the electron loses the energy and come back to the original level, light is emitted

The Atomic Emission Spectrum of Hydrogen the emission spectrum of hydrogen is the simplest emission spectrum because there is only one electron if had more than one electron, they would influence the other’s position it is not uniform, but concentrated into bright lines, indicating the existence of only certain allowed electron energy levels these four lines are called the Balmer series McGraw Hill animation link

convergence up here (levels are close together)

More about energy levels energy levels of atoms are NOT evenly spaced like the rungs of a ladder the higher the energy level, the smaller the difference in energy between successive energy levels becomes the energy difference between levels becomes less as the level number increases this means that the lines of a spectrum will converge (get closer together with increasing energy)

This is referred to as convergence of the spectral lines.

Scandium 3-D video (2:31) 3-D Graphic Examples of Atomic Orbitals