Review of

Oxygen (lavender light)

Ceiling light (white)

Flood light (white)

Continuous/like a rainbow

Thick bands of colors/ black spaces in between

Thin lines of color. Lots of black spaces in between.

NoNo

Nope

Depends

Spectral Lines from various elements

Compare & Contrast

Req. Energy; gives off

light

Glowing, white-hot metal (tungsten)

Mercury vapor causes phosphor coating to glow

Glowing gas (O2) or other gases

Continuous color (like rainbow)

Thick bands of color; black space in between

Very thin lines of color; lots of black space in between

Gas(es)Black spaces in between

Incandescent Fluorescent Bulb

Element Tube

(oxygen gas)

Incandescent uses a metal filament (tungsten) that glows white hot. The other two use energized gases to emit light.

Incandescent bulb’s spectrum is continuous (no black spaces). The other two have bands (thin lines) of color w/ black spaces in between.

The fluorescent bulb’s spectrum shows 5 thick bands of color, whereas the element (oxygen gas) tube has very thin lines of color.

Red light = lower frequency = less energy

Purple = higher frequency = higher energy

The Energy Levels (“orbits”) where electrons CAN “jump” out to (and then fall back from).

The specific Energy Levels/orbits where the electrons CAN’T go.

That electrons of atoms have specific Energy Levels. Electrons can jump from a lower to a higher energy level (orbit) but immediately fall back again & release this energy as light energy (as photons).

Frequency!

ET #33: What Big Ideas did Niels Bohr discover about the atom?

Bohr looked at the light spectrum given off by different elements.

•Determined electrons exist in different orbits (energy levels) around the nucleus.

•When electrons absorb energy, they get “excited” and jump to a higher energy level (orbit).

•When they “fall back”, electrons emit light energy: violet = higher energy emitted; red = lower energy.

http://www.colorado.edu/physics/2000/quantumzone/bohr.html

Electrons Jump!!

Smaller “jump” = Lower energy

Bigger “jump” = higher energy

Electron Energy Levels

nucelus

1st energy level

2nd energy level

3rd energy level

1999, Addison, Wesley, Longman, Inc.

Energyabsorbed

EnergyReleased

Spectra EmissionSpectra Emission16

When electrons are excited, they jump to higher energy levels.

As electrons fall back down, energy is re-emitted

the wavelength (color) depends on the energy level/orbit/shell from which it falls from

Electron Ladders

e-e- Ground state

Excited state

Electrons can only be atspecific energy levels,NOT between levels.