Ground State vs. Excited State

Ground State – all electrons are in the lowest possible energy levels (normal) ex. 2 – 8 – 18 – 32

Excited State – if given additional energy, electrons will “jump up” to higher energy levels, temporarily.

Excited State ex. 2 – 5 – 2 Ground State ex. 2 – 7

Spectra

(bright line)

(dark line)

Bright Line = Emission SpectraHow does this happen?

“Excited electrons” at higher energy levels will eventually release the extra energy and “fall back down” to ground state conditions.

During the “fall back”, energy is released as Visible Light Energy.

Wavelengths = Energy = Color Bands

Bright Line Spectra

Energy levels are NOT evenly

separated.

Bright Line – Emission Spectra

How are spectra formed?

Niels Bohr1913

Danish chemist

Bohr model of atom:

http://www.chemeng.uiuc.edu/~alkgrp/mo/gk12/quantum/

Bright Line Spectra

Each element has a specific electron configuration and a corresponding emission spectrum.

Emission (bright line) spectrum can be used to identify (“fingerprint”) each element.

http://www.colorado.edu/UCB/AcademicAffairs/ArtsSciences/physics/PhysicsInitiative/Physics2000/applets/a2.html

So Dude, check out the

colors!

Do the spectra lab.

Bright Line – Emission Spectra

Spectra

(bright line)

(dark line)

Flame Tests

- burn metal salts in a flame and observe/record the color

- compare colors to known standards for metals

- spectrascope not required

Sodium (Na) – Yellow flame

with Na salts like NaCl, NaBr

Potassium (K) –Violet flame

with KCl, KBr, etc.