Electrons And Light
Electromagnetic Radiation
Energy that travels as a wave through
space
Wavelength –λ – distance between
corresponding points on adjacent waves
Frequency – f – waves per second
Spectrum
Breakdown of electromagnetic radiation
by increasing wavelength
Visible light is one small portion of the
electromagnetic spectrum
Relationship Between
Electrons And Light
When energy is given to an atom, it
gives off light
When light is shined on certain metals,
they give off electron – Photoelectric
effect
By old theory, it doesn’t make sense
that they are related – electrons are
particles and light is a wave
Quantum Theory
Says that light travels in chunks (like
particles) that follow the path of a wave
Quantum – finite chunk of energy
Photon – a quantum of light
Since light acts as both a wave and a
particle it can interact with electrons
Light has a wave-particle duality
Bohr Model
In the atom, electrons exist in quantum
energy levels (n levels)
Electrons have the lowest energy when
closest to the nucleus
Under resting conditions, the electrons
are in the lowest possible energy level
called ground state
When atom absorbs a quantum of energy, it
causes the electron to jump to a higher
energy level called the excited state
Excited atom is energetically unstable, so
electron will fall back down very rapidly and
energy will given off in the same amount as
absorbed but now in the form of a photon of
light
Line Emission Spectrum
Electrons falling to and from different
levels produce different colors of light
Since every atom has different numbers
of electrons, each produces its own
unique color bands of light – line
spectrum
Spectroscopy is the process of using the
color bands to identify specific atoms
Line Spectrum For Hydrogen
True or False
The distance between two waves is called
the frequency.
A breakdown of waves by
wavelength is called
A) Electromagnetic Radiation
B) Spectrum
C) Visible light
D) Photoelectric Effect
A chunk of energy is called a
_________.
When electrons are in the
lowest energy level possible,
they are in
A) Ground state
B) Excited state
C) Main energy level
D) Orbitals
When electrons in the ground state
absorb energy, they leap to an
____________ state.
When electrons fall back down
from the excited state, they
release a __________.
A) chunk of energy
B) Quantum of energy
C) Photon of light
D) Electron
True or False
The line emission spectrum for every
atom is different since every atom has
different numbers of electrons.