![Page 1: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/1.jpg)
Electrons in Atoms
![Page 2: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/2.jpg)
Wavelength () - length of one complete wave measured in m, cm, or nm
In light it tells us which color it is
Frequency () - # of waves that pass a point during a certain time period, hertz (Hz) = 1/s
Amplitude (A) - distance from the origin to the trough (dip) or crest (peak Amount of energy the wave is carrying - height of wave. It
is measured in meters. In SOUND it tells us how LOUD it is. In LIGHT it tells how
BRIGHT it is.
![Page 3: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/3.jpg)
A
greater amplitude
greater frequency
crest
origin
trough
A
![Page 4: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/4.jpg)
Understanding electronic structure of atoms
Must understand light
Emitted and absorbed by substances. Visible light - type of Electromagnetic Radiation (EM)
Carries (radiant) energy through space Travels at speed of lightExhibits wavelike behavior.
Think of light as particlehelp understand how EM radiation and atomsinteract
![Page 5: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/5.jpg)
LOW
ENERGY
HIGH
ENERGY
![Page 6: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/6.jpg)
Move through a vacuum at the
‘speed of light’ 3.00 x 108 m/s
Behaves like waves that move through water
Result of energy transferred to the water (from
a stone)
Expressed as up and down movement
Both electric and magnetic properties
![Page 7: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/7.jpg)
Wave Speed = (distance between wave peaks) x (frequency)
= (wavelength)
x (frequency)
EM radiation moves through a vacuum at the “speed of light”
3.00 x 108 m/s also called c. A lower energy wave (infrared and red) has a longer
wavelength() and lower frequency(f)
A higher energy wave (blue - violet) has a shorter
wavelength() and higher frequency(f).
![Page 8: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/8.jpg)
Frequency & wavelength are inversely proportional
c = c: speed of light (3.00 108 m/s): wavelength (m, nm, etc.): frequency (Hz)
![Page 9: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/9.jpg)
EX: Find the frequency of a photon with a wavelength of 434 nm.
GIVEN:
= ?
= 434 nm = 4.34 10-7 m
c = 3.00 108 m/s
WORK: = c
= 3.00 108 m/s 4.34 10-7 m
= 6.91 1014 Hz
![Page 10: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/10.jpg)
Planck (1900)
Observed - emission of light from hot objects
Concluded - energy is emitted (absorbed or released) in small, specific amounts (quanta)
Quantum - smallest energy packet that can be emitted or absorbed as EM radiation by an atom.
![Page 11: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/11.jpg)
E: energy (J, joules)h: Planck’s constant (6.6262 10-34 J·s): frequency (Hz)
E = h
Planck proposed that the energy, E, of a single quantum energy packet equals a constant (h) times its frequency
The energy of a photon is proportional to its frequency.
![Page 12: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/12.jpg)
EX: Find the energy of a red photon with a frequency of 4.57 1014 Hz.
GIVEN:
E = ? = 4.57 1014 Hzh = 6.6262 10-34 J·s
WORK:
E = h
E = (6.6262 10-34 J·s)(4.57 1014 Hz)
E = 3.03 10-19 J
![Page 13: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/13.jpg)
Energy is always emitted or absorbed in whole number multiples of hv, such as hv, 2 hv, 3 hv, 4hv, ….
The allowed energies are quantized values are restricted to certain quantities.
The notion of quantized rather than continuous energies is strange.
Ramp vs Staircase Ramp - vary the length your steps and energy used on
the walk up. Stairs - must exert exactly the specific amount of
energy needed to reach the next step. Your steps on steps are quantized, you cannot step
between them.
![Page 14: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/14.jpg)
Planck (1900)
vs.
Classical Theory Quantum Theory
![Page 15: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/15.jpg)
Einstein (1905)
Observed – photoelectric effect
Dispersed light falls on metal samples, the different frequencies produce different energetic photoelectrons
![Page 16: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/16.jpg)
Einstein (1905)
Concluded - light has properties of both waves and particles (photons)
“wave-particle duality”
Photon - particle of light that carries a quantum of energy
Used planck’s quantum theory to deduced that: Ephoton = hv
![Page 17: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/17.jpg)
Electrons in Atoms
![Page 18: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/18.jpg)
ground state
excited state
ENERGY IN PHOTON OUT
Elements’ atoms absorb electrical energy
e- get excited, become unstable, and release energy
Energy is in form of light
Set of frequencies of EM waves
![Page 19: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/19.jpg)
e- exist only in orbits with specific amounts of energy called energy levels
Therefore…
e- can only gain or lose certain amounts of energy
only certain photons are produced
Ground state = lowest allowable atomic electron energy state
Excited state = any higher energy state
![Page 20: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/20.jpg)
Energy of photon depends on the difference in energy levels
Bohr’s calculated energies matched the IR, visible, and UV lines for the H atom
1
23
456
![Page 21: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/21.jpg)
Each element has a unique bright-line emission spectrum. “Atomic Fingerprint” Helium
Examples: Iron
Now, we can calculate for all elements and their electrons – next section
![Page 22: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/22.jpg)
![Page 23: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/23.jpg)
Louis de Broglie (1924)
Proposed eˉ in their orbits behave like a waveEVIDENCE: DIFFRACTION PATTERNS
ELECTRONSVISIBLE LIGHT
![Page 24: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/24.jpg)
Heisenberg Uncertainty Principle Impossible to know velocity and position of an
electron at the same time
Trying to observe an electron’s position changes its momentum
Trying to observe an electron’s momentum changes its position
Electrons cannot be locked into well-defined circular orbits around the nucleus.
![Page 25: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/25.jpg)
Orbital (“electron cloud”) a specific distribution of electron density in space. Each orbital has a characteristic energy and shape.
Orbital
![Page 26: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/26.jpg)
Specify the “address” of each electron in an atom
UPPER LEVEL
![Page 27: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/27.jpg)
1. Principal Quantum Number (n = 1, 2, 3, …) (see periodic table left column)
Indicates the relative size and energy of atomic orbitals
As (n) increases, the orbital becomes larger, the electron spends more time farther from the nucleus
Each major energy level is called a principle energy level Ex: lowest level = 1 ground state, highest level = 7 excited state
![Page 28: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/28.jpg)
2. Energy Sublevel Defines the shape of the orbital (s, p, d, f)
# of orbital related to each sublevel is always an odd # s = 1, p = 3, d = 5, f = 7
Each orbital can contain at most 2 electrons
s p d f
![Page 29: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/29.jpg)
Subscripts x, y, z designates orientation Specifies the exact orbital within each
sublevel
![Page 30: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/30.jpg)
px py pz
![Page 31: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/31.jpg)
4. Spin Quantum Number ( ms ) Electron spin +½ or -½
An orbital can hold 2 electrons that spin in opposite directions.
![Page 32: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/32.jpg)
Pauli Exclusion Principle A maximum of 2 electrons can occupy a single
atomic orbital
Only if they have opposite spins
1. Principal #
2. Energy sublevel 3. Orientation
4. Spin #
energy level
(s,p,d,f)
x, y, z
exact electron
![Page 33: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/33.jpg)
Electron Configuration
Electrons in Atoms
![Page 34: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/34.jpg)
A. General Rules
Aufbau Principle
Electrons fill the lowest energy orbitals first.
“Lazy Tenant Rule”
![Page 35: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/35.jpg)
RIGHTWRONG
A. General Rules
Hund’s Rule
Within a sublevel, place one e- per orbital before pairing them.
“Empty Bus Seat Rule”
![Page 36: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/36.jpg)
O
8e-
Orbital Diagram
Electron Configuration
1s2 2s2 2p4
B. Notation
1s 2s 2p
![Page 37: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/37.jpg)
Shorthand Configuration
S 16e-
Valence ElectronsCore Electrons
S 16e- [Ne] 3s2 3p4
1s2 2s2 2p6 3s2 3p4
B. Notation
Longhand Configuration
Valence electrons: determine chemical properties of that
element & are the electrons in the atoms outermost orbital
![Page 38: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/38.jpg)
© 1998 by Harcourt Brace & Company
sp
d (n-1)
f(n-2)
1234567
67
Notation
![Page 39: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/39.jpg)
1
2
3
4
5
6
7
Shorthand Configuration Core e-: Go up one row and over to the
Noble Gas. Valence e-: On the next row, fill in the #
of e- in each sublevel.
Shorthand Notation
![Page 40: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/40.jpg)
[Ar] 4s2 3d10 4p2
C. Periodic Patterns
Example - Germanium
![Page 41: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/41.jpg)
Full energy level
1
2
3
4 5
6
7
Full sublevel (s, p, d, f)Half-full sublevel
D. Stability
![Page 42: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/42.jpg)
Electron Configuration Exceptions
Copper
EXPECT: [Ar] 4s2 3d9
ACTUALLY: [Ar] 4s1 3d10
Copper gains stability with a full d-sublevel.
D. Stability
![Page 43: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/43.jpg)
Electron Configuration Exceptions
Chromium
EXPECT: [Ar] 4s2 3d4
ACTUALLY: [Ar] 4s1 3d5
Chromium gains stability with a half-full d-sublevel.
D. Stability
![Page 44: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/44.jpg)
D. Stability
Ion Formation Atoms gain or lose electrons to become
more stable. Isoelectronic with the Noble Gases.
![Page 45: Electrons in Atoms. Wavelength ( ) - length of one complete wave measured in m, cm, or nm In light it tells us which color it is Frequency ( ) -](https://reader035.vdocument.in/reader035/viewer/2022081513/56649f1d5503460f94c348ba/html5/thumbnails/45.jpg)
O2- 10e- [He] 2s2 2p6
D. Stability
Ion Electron Configuration
Write the e- config for the closest Noble Gas
EX: Oxygen ion O2- Ne