Electron Location
Chapter 5
Lec 5 | MIT 3.091 Introduction
to Solid State Chemistry
Animations of Electron Levels
Electron “jumping” website
 Electron levels animation link
 McGraw Hill animation link
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Jumping Electrons
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normally electrons exist in the ground state,
meaning they occupy the lowest energy level
possible (the electron shell closest to the nucleus)
when an electron is excited by adding energy to
an atom (for example, when it is heated), the
electron will absorb energy, "jump" to a higher
energy level
after a short time, this electron will spontaneously
"fall" back to a lower energy level, giving off a
quantum of light energy called a photon
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the key to Bohr's theory was the fact that the
electron could only "jump" and "fall" to precise
energy levels, thus emitting a limited spectrum of
light.
 quantum is the amount of energy required to
move an electron from one energy level to
another
Quantum Numbers
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electrons display the properties of both waves and
particles.
think of an atom as a very bizarre house (like an
inverted pyramid) with the nucleus living on the
ground floor, and then various rooms (orbitals) on
the higher floors occupied by the electrons
electrons fill low energy orbitals (closer to the
nucleus) before they fill higher energy ones
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electron configuration is defined to be the
arrangement and distribution of electrons in
atomic orbitals
 the electron configuration of each atom is
made up of four quantum numbers, which
describe different properties of each electron
and its orbital.
Where is an electron?
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What level/size?
What shape?
Orientation?
Spin?
Quantum numbers give “the address” of the
electron.
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Principle quantum number (n) - describes the
SIZE of the orbital or ENERGY LEVEL of the
atom.
Angular quantum number (l) - describes the
SHAPE of the orbital.
Magnetic quantum number (m) - describes an
orbital's ORIENTATION in space. This tells the
placement of the electrons in the sub-orbitals
Spin quantum number (s) - describes the SPIN
or direction (clockwise or counter-clockwise) in
which an electron spins.