Transcript Quantum Number Describes

Chapter 5 Review
Wave Nature of Light



WavelengthThe distance between two consecutive peaks
or troughs.
FrequencyThe number of waves that pass a point each
second (the unit is the Hertz, Hz). One
complete wave or cycle per. second = 1 Hz.
VelocityDistance a peak moves in a unit of time.
Particle Nature of Light
PHOTOELECTRIC EFFECT
 When light shines on certain metals an
electric current is produced (electrons are
emitted from the metal).
 Not explained by the wave theory of
light…
 Light is thought of as a stream of particles
called…
Bohr’s Model
absorbs energy  electron ‘jumps’
to a higher energy level (orbit).
 Atom
 Electron
‘jumps’ to a lower orbit  energy
released (photon).
 Energy
difference between the two orbits
 energy of the photon The color
(frequency) of light produced E = h f
Bohr’s Shortcomings

Quantized energy levels were not
immediately accepted by other scientists
(though correct)

Worked for hydrogen but not for other
elements with more electrons.
Heisenberg Uncertainty Principle

It is impossible to determine
simultaneously the position and velocity of
an electron or any other particle.
Orbital

A three dimensional region around the
nucleus that indicates the most probable
location of the electron.
Quantum Numbers
Describe the properties of atomic orbitals
and the electrons that occupy them…
Quantum Number
Describes
 Principle
main E. level
 Angular Momentum - shape of Orbital
 Magnetic
orientation of orbital
 Spin
orientation of electron

Rules for Writing e- configurations
An electron occupies the lowest energy
orbital that can receive it…(like filling a
glass)
 If two electrons occupy the same orbital
they must have opposite spins!
 Orbitals of equal energy are each
occupied by one electron before any
orbital is occupied by a second electron.

1S2 2S2 2P2
What do the symbols
represent?
Write Orbital notation for

Nitrogen
Electron configuration for:

Ne
1S2 2S22P6
Nobel Gas Notation for:
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Aluminum
Al [Ne] 3S2 3P1
How does the arrangement of
electrons relate to an elements
position on the periodic table?

….where would find an element with an
outermost energy level like this 4S24P4 ?
Calculate Frequency and energy

Wavelength = 4.5 x 10-7 meters
Region outside of nucleus where
an electron can most probably
be found

Orbital
An electron in the lowest
possible energy level said to be
in it’s

Ground state
When an electron absorbs
energy it will be in…

An excited state
A photon is released when an
electron moves from

Excited state to ground state
A quantum of electromagnetic
energy is a

Photon
How does an orbit differ from an
orbital?
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Orbitals do not show the exact location or
path of an electron… only the probable
location
It is not possible to know the
precise location and velocity of
an electron or other small
particle (“what is…”)

Heisenberg uncertainty principle
Indicates the main energy level of
an orbital or electron

Principle quantum number
An electron at main energy level 5
has more ___ than an electron at
main energy level 2

Energy
Dumbell-shaped set of 3 orbitals

P ORBITALS
Indicates the orientation of the
orbital with regard to a three
dimensional axis

Magnetic quantum number
A spherical electron cloud

S orbital
The difference between a 2S orbital
and a 3S orbital

Distance from nucleus or energy level
An electron occupies the lowest
energy orbital that can receive it

Aufbau principle
Orbitals of equal energy are each
occupied by one electron before
any is occupied by a second
electron.

Hund’s Rule
Two electrons in the same
orbital must have opposite spins

Pauli exclusion principle
The Bohr model was an attempt to
explain what about hydrogen

Bright line or line emission spectrum
The number of electrons in the
highest occupied energy level of
argon (a noble gas)
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8
The distance between successive
peaks on a wave
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wavelength