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