Chemistry Astrobiology Lab

Hydrogen Spectra

Moving beyond the Flame Test

• Students in Regents level chemistry are required to identify unknown elements looking at spectra

• This lab allows students to explore and fully understand the bright line spectra

Hydrogen Emission

• Using the gas discharge tubes for hydrogen students color the four lines in the bright line spectra

Emission vs. absorption spectra

• Students often confuse emission spectra of gas discharge tube with absorption spectra of stars

• Web interactive

Absorption Lines from Stars

• Using data students will now observe the absorption lines from the seven types of stars

• Credit: simulated stellar spectrum from the European Space Agency’s educational website

O

O

B

A

F

G

K

M

HHHH

O

B

A

F

G

K

M

Understanding Stars

• Students connect emission lines to exact position of the stars absorption lines

• Students begin to understand that all stars do not have the same amount of hydrogen

Number Crunching

• Students calculate the Energy of the photon of the four lines of the Balmer Series:

• Use formula E=hc– λ

Connection to PEL

• Students than connect the energy of the photon to the exact movement of the electron

• Using Formula E=-1312KJ/n2

• Students find the Energy of the 3rd and 2nd energy levels

Connection to Lines

• Students subtract the 2nd PEL energy they calculated from the 3rd to get the energy released when an electron drops from the third to the second PEL

• They then connect 3.0 x 10 -22 KJ to the red line which explains the movement of electron from the 32 PEL

Looking deeper into Hydrogen lines• The stellar spectra for the seven dwarf

stars is studied and the depth of the hydrogen lines is further observed• Points to consider:

• Not all stars have same amount of H• Lines are deepest in mid temperature stars• Lines are weak at O and A for different reasons!

HHH

H 656.3 nmH 486.1 nmH 434.0 nmH 410.2 nm

Credit:

• The figure in slides is from an online lecture by Richard Pogge, Ohio State Univ.

• Both Slides were highlighted from Wayne Roberge

Future Seminars

• Astrobiology Seminars November 22, 2010 Dr. Roger SummonsMIT

Thank you!

• I would like to thank the following:• Dr. John Delano

University at AlbanyDr. Wayne RobergeRensselaer Polytechnic Institute

• Dr. E. Bruce WatsonRensselaer Polytechnic Institute

• Paul Zachos ACASE