Electron Shells
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Transcript Electron Shells
Electron Configuration and
Energy Levels:
Ground state:
All the electrons in an atom have the
lowest possible energies
Most stable electron configuration
Example: Sodium (Na)
Pictures show all the
electrons in a sodium atom
Neutral Sodium has 11
protons (p+) and 11
electrons (e-)
First layer fills up with 2
electrons - 9 left over
Next layer fills up with 8
electrons - 1 left over
Last electron is all alone in
the next layer
All of the Electron Shells
Electron Energy Levels:
Analogy: staircase.
•Can stand on a stair, not between stairs.
•It takes energy to raise from a lower
stair to a higher stair.
•In the same way, electrons can be in
lower or higher energy level but not in
between.
Electron Configuration and
Energy Levels:
Electrons can not exist between energy
levels (shells).
They must jump from one level to the next.
Energy must be added to atom for
electron to jump to higher energy level.
When electron falls back to it’s original
state, energy is released as specific
wavelength of light.
Electron at
Ground State.
Electrons become
excited, and
move to a higher
energy level.
Add energy in the
form of heat.
Electron
returns
to
Ground
State
Energy
is given
off as
light.
Emission Spectrum
Each element has different “energy staircase” ,
i.e. unique series of electron energy steps.
To move between steps, electrons absorb or
emit specific amounts of energy,
Amount of energy corresponds to specific
wavelengths (colors) of light.
Emission spectrum: unique series of energy
differences (i.e. colors) between steps allows
identification of elements by light energy they
emit.
Red . Orange . Yellow . Green . Blue . Indigo . Violet
Red
Long wavelength
Orange
Less Energy
Yellow
Green
Blue
Indigo
Violet
Short wavelength
Greater Energy
Flame Test
We will place samples of elements into a
flame.
This will add energy to the atom in the
form of heat.
The electrons will them become excited,
and jump to a higher energy level.
Flame Test
Then the electrons will return to their
original ground state.
As they return to a lower energy level, the
energy will be given off in the form of light.
Different elements will have different flame
colors because of their unique electrons.
This characteristic spectrum can be used
to identify an element.