SciTech presents: Hands-On Atom

WHAT TO NOTICE:

• this model of a Hydrogen atom has three states
• it is usually in its ground state, its lowest energy state
• if you CLICK when the xylophone stick is outside the xylophone, the electron will bounce around in its shell - from the uncertainty principleyou never know the exact position and velocity of the electron
• the radii (distance of the electron from the nucleus) of the 3 states, 1, 2, and 3 are in the ratio 1:4:9

WHAT TO DO:

• you can "excite" the atom to its n=2 state by flashing a green photon at it - CLICK
• you can also "excite" the atom to its n=3 state by flashing a blue photon at it - CLICK
• when the atom is in its n=2 state, you can excite it further with a red photon - CLICK again QUICKLY
• watch the atom return to the ground state and emit a photon
• if it drops from the n=2 state to the ground state that photon will be green (in a real hydrogen atom it is too short a wavelength for eyes to see!)
• if it drops from the n=3 state to the ground state that photon will be blue(in a real hydrogen atom it is too short a wavelength for eyes to see!)
• if it drops from the n=3 state to the n=2 state (on its way to the ground state) the photon will be red (as in a real hydrogen atom - the same red as the H-alpha filter in SciTech's solar telescope)

C major equal tempered scale (A 440) (numbers in Hertz)
C	D	E	F	G	A	B	C
523.25	587.33	659.26	698.46	783.99	880.00	987.77	1046.5

our metaphor is WAVELENGTH

• shorter wavelength means higher frequency
• shorter wavelength means a higher energy photon ("particle" of light)
• COLOR: blue has a shorter wavelength than red
• SOUND: a higher tone has a shorter wavelength than a lower tone

A copy of our hands-on atom is in  Japan!

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by E. Malamud. revised April 8, 1999