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Spectral Emission
Every element has its own characteristic spectral emission
Just as every fingerprint is unique, so is each spectral emission for each element on the periodic table
How and Why does an element give off color?
Each element has its own unique configuration
Changing Levels
Electrons have different energy levels, like floors in a building.
Lowest is called the Ground State.Higher states are Excited States.
Photons of light
…so they each emit (give off) different frequencies of light when electrons change from one energy level to another
Each element has its own unique configuration of light
These are the “fingerprints” of the atom
https://www.youtube.com/watch?v=-d23GS56HjQ
Flame tests and emission spectra both help us identify different elements
The light from hot gases and light sources can be analyzed with a spectroscope
The colors appear b/c of their different frequencies
This is called a line spectrum
The lines will always stay in the same position as the continuous spectrum of light
Actually…much of what scientists know about the structure of the atom is from the study of atomic spectra
The elements of the sun and galaxies was discovered from spectral lines
The element Helium was discovered on the sun (1868) first before it was discovered on Earth (1895)
Astronomers
Gases, stars, planets made up of MANY elements have spectra which include ALL of the component spectral lines.
It’s the scientist’s job to figure out which lines belong to which element.
This is how we find out what a star is composed of.
Napoleon Bonaparte-1821
After his death, scientists examined his hair with a spectroscope. Murder was initially suspected, b/c arsenic (40x normal), a poison, was found.
Although the initial diagnosis of death was perforated stomach ulcer, turned cancerous…the arsenic exacerbated his condition
Review
How are photons of light created?
What is given off (emitted) when an electron moves from a higher energy level to a lower one?
Which has a higher energy level, red or violet?
What does spectral emission tell us?
The elements found in stars and galaxies
That each element has its own unique fingerprint when producing light
Lab Activity
1) Flame test
2) Spectroscopes