Hydrogen Atom Spectrum Flashcards
(22 cards)
What happens when an atom is heated? x2
When an atom is heated, it absorbs energy as it becomes excited, which is re-emitted as radiation as it falls down to its ground state.
Characteristic of this radiation when seen using a prism?
Series of discrete lines Each discrete line = different energy = different wavelength = different frequency
How does the frequency / energy differ when a given atom absorbs and emits radiation?
The EM radiation absorbed and emitted have the same frequency for a given atom.
Main difference between emission spectra and absorption spectra?
Emission = colours Absorption = gaps
Difference between wavelength and frequency?
Literally what it means.
Wavelength = length of wave (short or long)
Frequency = how many waves in a given time
Relationship between wavelength and frequency?
Shorter (smaller) wavelenth = higher frequency (high energy)
Longer (larger) wavelength = lower frequency (low energy)
What is the emission spectrum?
The amount of light emitted at different wavelengths is called an emission spectrum.
Only specific wavelengths i.e. colours are seen.
What is the unit of measurement for wavenumber?
cm-1
What is the unit of measurement for wavenumber?
nm
What is the symbol to represent wavelength?
λ
units = nm
How to figure out wavenumber (cm-1) from wavelength (nm)?
wavenumber = 1 / λ
i.e. reciprocal of wavelength = 1 over wavelength
What is the formula to predict the energies of the observed lines in an emission spectra?
wavenumber = 1/λ = RH (1/m2 - 1/n2)
What is the Rydberg constant and what is it used for?
R or RH = 1.097 x 105 cm-1
What does m stand for in the wavenumber formula?
m = innermost shell
What does n stand for in the wavenumber formula?
n = bigger integer than m
What are the three IR series called?
m = 3 = Paschen series (IR)
m = 4 = Brackett series (IR)
m = 5 = Pfund series (IR)
What are the frist two series called?
Lyman (UV) & Balmer (partly visible)
Which series has more energy?
Lyman > Balmer > IR (Paschen, Brackett, Pfund)
Why does Lyman series have higher energy than IR series?
Shorter wavelength and higher frequency.
Which series has longer wavelength, Lyman or Paschen?
Paschen series has longer wavelengths.
What does n stand for?
n = principle quantum no.
n = main energy level
n = shell
Why does higher principle quantum no. (n) have higher energy levels?
This is because the shells become more far away from the nucleus as the principle quantum number increases.
