ElectronsArrangement in the AtomKey words: Energy, wavelength, frequency, photon
Use these terms in a sentence (s) which makes sense.
Objectives
• To use the “Bohr Model for Hydrogen Atom” and “Electromagnetic Spectrum” diagrams from the Reference Tables to relate color, frequency, and wavelength of the light emitted to the energy of the photon.
• To understand the inverse relationship between wavelength and frequency, and the direct relationship between energy and frequency.
Electrons will give off electromagnetic radiation
-When “energized” by heat, electricity, light or chemical reactions.
How and why does this happen?
Energy exists in photonsA photon has a specific amount
(or packet) of energyAlso use the word “quantum of
energy”
Photons with different energy will have specific wavelengths related to the energy
Bohr’s model
Bohr’s Model of the AtomElectrons orbit the nucleus at:At the lowest energy level possibleCalled the ground state
Electrons can be excited by:Electricity, light, chemical reactions
When excited, an electron will absorb only a certain amount of energy,
A “packet” of energy called a photon or quantum
Bohr’s model
Bohr’s model
When excited, the electronWill jump to a higher energy
level ◦Called the excited state
The electron does not stay in the excited state but falls back toward the nucleus and releases energy
Bohr provided critical information Ground vs. excited state
Number of electrons that exist at specific energy levels
Bohr’s model works for hydrogen but not for the complex atoms
Emission Spectrum LabPurpose: To relate the unique emission spectra lines of an element to the energy levels of the atom.
Essential Question: What are the emission spectra for specific elements?
This is?
How do neon lights produce the glowing colors? FACTS: Neon is a colorless, inert (non-
reactive, non-flammable) gas
Neon lights are tubes filled with neon gas.
Neon atoms
Normal conditions◦Electrons are at the ground state◦No light (energy) is emitted
Electricity passing through the tube◦Atoms absorb energy◦Electrons become excited and
unstable◦Electrons are pulled back toward the
nucleus◦Electromagnetic radiation is emitted
Elements and their electromagnetic radiationEmissions spectrumUnique for each element Electrons are excited by
electricity When they are pulled back by the
____________, they give off __________
Emission SpectrumWhite light
◦Write the order of the colors
Hydrogen: Nitrogen:Mercury:Neon:Other:
Emission Line Spectra
Emissions Spectra - Simulation
http://phet.colorado.edu/en/simulation/discharge-lamps
Produce light by bombarding atoms with electrons. See how the characteristic spectra of different elements are produced, and configure your own element's energy states to produce light of different colors.
Emission SpectraUnique for each elementUsed to identify elements as part
of unknown compounds
Hubble Space Telescope
Bohr Model Animationsfor Elements 1-11http://web.visionlearning.com/cus
tom/chemistry/animations/CHE1.3-an-atoms.shtml
http://web.visionlearning.com/custom/chemistry/animations/CHE1.3-an-atoms.shtml