warm up what is the wavelength defined as? you are given the wavelength of a particle as being 6.3 x...
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Warm UpWhat is the wavelength defined as?You are given the wavelength of a particle as
being 6.3 x 10 -5 m. What is the frequency of the particle?
You are given the frequency of a particle as 7.43 x 1014 Hz. What is the wavelength?
HINT: Speed of light = 3.00 x 108 m/s
ChemistryUnit Three, Day Two
Kimrey18 September 2012
Electromagnetic SpectrumShows the different types of radiation –
different wavelengths.
Radio Waves
Radio waves are electromagnetic waves with the longest wavelengths (longer than 1mm)
They are used in communications, radar, microwaves, and MRIs
MicrowavesMicrowaves
are radio waves with wavelengths less than 30 cm but longer than 1mm
Cell phones and satellites use microwaves
• Microwaves in microwave ovens cause water molecules to rotate, heating your food
Infrared WavesInfrared waves
have wavelengths between 1mm and 750 billionths of a meter
Thermal energy travels in infrared waves • Remote controls and
CD-ROM drives also use infrared waves
Visible LightThe visible spectrum is the light we can seeIn order from largest wavelength to smallest:
Red, Orange, Yellow, Green, Blue, Indigo, Violet (Roy G Biv)
The color you see is the color that is reflected.
White is all colors, black is no color. The longer the wavelength, the less
penetrating (including less dangerous to cells)
Visible Light
(ROYGBIV)
Ultraviolet Waves Ultraviolet, or UV
waves, have wavelengths of 400 billionths to 10 billionths of a meter
UV waves can cause skin damage such as sunburn, wrinkling, and cancer
Ultraviolet LightUV light enables your
body to make vitamin DUV waves can kill
bacteria by damaging its DNA
X-RaysX-rays have
wavelengths between ten billionths of a meter and ten trillionths of a meter
X rays are commonly used by doctors
and dentists
Gamma Rays
Gamma waves have wavelengths shorter than 10 trillionths of a meter
Gamma rays are produced by radioactive decay or other subatomic processes
The Bohr Model Created by Niels Bohr in 1913.Related the energy of an electron to the
orbital it would occupy. Similar to the model of the solar system with
the nucleus as the sun.
• 1st shell can hold 2 electrons.• 2nd can hold 8.• 3rd can hold 18• 4th can hold 32
Making Bohr ModelsStep One: Write the number of protons and
neutrons in the nucleus. Step Two: Add electrons in their appropriate
orbitals until you have reached the correct number of electrons.
ExampleDraw a Bohr model for Mg-24.
You TryDraw a Bohr model for the following:
Nitrogen-14Aluminum -27Sodium-23+1
Conclusions from the Bohr ModelElectrons are both Particles AND waves. We cannot know for certain where an
electron is.We cannot know for certain how fast an
electron is moving. The more we know about the location of an
electron the less we know about its’ movement and vice versa.
Bohr Model and LightBohr went a step further as well, he
determined that each orbital corresponded to a certain energy level.
As electrons become excited they can “jump” to a higher energy level.
When these electrons return to their ground state (normal energy level) they emit the difference in energy levels.
NOTE!!! Electrons can ONLY exist at a specific orbital NOT between orbitals.
Reading the Bohr Model
ExampleWhat is the wavelength of light emitted when
an electron goes energy level 4 to energy level 1?
(n=4 n=1)97 nm
You TryWhat is the wavelength of light emitted when
an electron goes from n= 3 to n = 2?What type of light would this be classified as? A photon with a wavelength of 656 nm is
emitted from a hydrogen atom. What energy state did this electron start in and end in?
Bohr Model for H Atom
Example ProblemsWhat type of light has a wavelength of 1 x 10-11 m? What type of light is released when an electron jumps
from = 4 to n = 1 in a Hydrogen atom?What type of light has a wavelength of 6.3 x 10 -7m?Is light energy released or absorbed in the following
jumps of an electron in a Hydrogen atom?n=1 to n = 3 n = 2 to n = 5 n = 6 to n = 3n = 2 to n = 3
Rank the following types of light in increasing energy:X – ray, green light, microwaves, violet light.