Download The Mass Spectrometer

Electrons “in Orbit”
Topic 2.1
The electromagnetic spectrum
Know the following about the EM
spectrum:
• visible, infrared, and UV regions
• describe the variation in:
– wavelength
– frequency
– energy
– colors for visible light
Know what is
in the red
boxes
The Electromagnetic Spectrum
High frequency
lower frequency
Short wavelength
longer wavelength
High energy
lower energy
Continuous vs. Line Spectrum
• continuous spectrum
– produced by light as it passes through a
prism
• in the case of white light, all colors are seen
• there are no levels
• emission line spectrum
– energy is applied to a specific element
• this “excites” the element and the light is viewed
through a spectroscope
– a continuous spectrum is NOT observed, but a series of
very bright lines of specific colors with black spaces inbetween instead
– unique for every element and are used to identify atoms
(much like fingerprints are used to identify people)
More on emission line spectrum
Give off energy
when falls back
down to
normal energy
level
– the process
• electrons surround the nucleus in specific orbitals
or energy levels
• when electrons are excited (heat/electricity) they
can move to a higher energy level
• when they move back down they emit energy in
the form of electromagnetic radiation
• because electrons can only exist in certain energy
levels, only certain transitions can occur
• the color of the light emitted depends on the
frequency of the emitted photon
• http://www.youtube.com/watch?v=QI50GBUJ48s
this is a repetitive slide- just couldn’t bear to delete it
1. an electron in the
atom gains (absorbs)
energy from heating
2. electron jumps up an
energy level.
3. electron is now
unstable (unwelcome)
in this level and is
“kicked out”
4. when the electron
loses the energy and
come back to the
original level, light is
emitted
The Atomic Emission Spectrum of
Hydrogen
• the emission spectrum of hydrogen is the simplest
emission spectrum because there is only one electron
– if had more than one electron, they would influence the
other’s position
– it is not uniform, but concentrated into bright lines,
indicating the existence of only certain allowed electron
energy levels
– Electron “jumping” website
– McGraw Hill animation link
convergence
up here
(levels are
close
together)
More about energy levels
• energy levels of atoms are NOT evenly spaced like
the rungs of a ladder
– the higher the energy level, the smaller the
difference in energy between successive energy
levels becomes
– the energy difference between levels becomes
less as the level number increases
– this means that the lines of a spectrum will
converge (get closer together with increasing
energy)
IB-- this is referred to as
convergence of the
spectral lines
This is referred to as
convergence of the
spectral lines.