Quantum

The amount of energy needed to move an

electron from it’s present energy level to the next

higher one

Ground State

The lowest energy level occupied by an electron when an atom is in its

most stable energy state

Electromagnetic Radiation

A series of energy waves that travel in a vacuum at 3.0 X 1010 cm/s; includes

radio waves, microwaves, visible light, infrared and ultraviolet light, x-rays,

and gamma rays

Frequency

The number of wave cycles that pass a given

point per unit of time; there is an inverse

relationship between a frequency and the

wavelength of a wave

Hertz

The SI unit of frequency equal to one cycle per

second

Spectrum

Range of wavelengths of electromagnetic

radiation; wavelengths of visible are separated when a beam of white light passes through a

prism

Atomic Emission Spectrum

A pattern of frequencies obtained by passing light

emitted by atoms of an element in the gaseous state through a prism;

the emissions spectrum of each element is

unique to that element

Planck's Constant

A number used to calculate the radiant energy absorbed or

emitted by a body based on the frequency of

radiation

Photons

A quantum of light; a discreet bundle of

electromagnetic energy that behaves as a

particle

Laboratory 3Atomic Emissions

For this demonstration, you will observe a tube of hydrogen gas connected to a high-

voltage power suppiy. This light can be viewed through a spectroscope or a

diffraction grating lens. When the slit at the end of the spectroscope is aimed toward

the light, the colors of the spectrum appear separately off to the sides of the slit

Laboratory 3Atomic Emissions

a) What colors do you see in the spectrum of light given off by hydrogen gas?

b) Make a drawing in your Notebook of what you see inside the spectroscope. Make sure to label each band with the colors and spacing between them that you observe.

Laboratory 3Atomic Emissions

Now we’ll repeat this process for two other elements, helium and argon.

Laboratory 3Atomic Emissions

Laboratory 3Atomic Emissions

Metals can be identified by characteristic colors, when a compound containing the metal is heated in a burner flame. The purpose of this demonstration is to show the colors and to associate them with the metal in the compound.

Note: All the anions are the same (chloride) and do not give a color.

Laboratory 3Atomic Emissions

Materials

BaCl2, CaCl2, CuCl2, SrCl2, NaCl, KCl

Bunsen Burner

Procedure

Soak wooden sticks in 1 M solutions of each salt overnight.

Hold stick over Bunsen burner flame and observe color.

Laboratory 3Atomic Emissions

Observations

Metal Cation Color

Fe2+

Ca2+

Cu2+

Sr2+

Na1+

K1+