1. Nature of light and atomic spectrum

2. Energy from the sun
Fusion – process of 2 nuclei that combine to make one (a new element ) and emitting large amounts of energy.
The sun is a giant ball of hydrogen gas undergoing a fusion reaction – releasing energy.
We know that energy as electromagnetic radiation

3. How is light formed?
All electrons in an atom exist naturally in their “ground state” e- configuration (all want to be close to nucleus – lower in energy)
If energy is added – electrons move to higher energy level – “excited state” – but don’t stay.
Electrons fall back to ground state and release light

4. How is light formed?
An electron will jump to a higher energy level by absorbing energy.
An electron will fall back to ground state by releasing light

5. White Light – from the sun
Passes through prism & separates into continuous spectrum.
Called continuous because all colors are visible – no blank areas

6. Light - from heated chemicals
Passes thru prism & separates into an emission line spectrum.
Emission line spectrum is not continuous – has blank areas in the spectrum
All elements have a different emission line spectrums – depends on number of electrons.

7. continuous
emission
absorption

8. Hydrogen spectrum
The light of the gas is split into its components or an emission spectrum
Helium spectrum

9. What is a spectroscope?
Instrument designed to visually observe spectra by splitting the LIGHT into its components.
Usually has PRISM or a DIFFRACTION GRATING to split light into components.
Diffraction gratings consist usually of thousands of narrow, closely spaced parallel slits (or grooves).

10. Electromagnetic Spectrum

11. Seeing light in color White light contains all visible light spectrum
R O Y G B V
We see….
Black – absorbing all colors
White – reflecting all colors
Color – ex: red – reflecting red and absorbing all other colors

12. White light passed through a prism

13. One color of light passed through a prism