Transcript Every element has its own characteristic spectral

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