Transcript
Quantum Model of the Atom
Electrons in Atoms
Quantum Mechanics
Radial Distribution CurveOrbital
Orbital (“electron cloud”)
Region in space where there is 90% probability of finding an e-
Quantum Numbers
UPPER LEVEL
Four Quantum Numbers:
Specify the “address” of each electron in an atom
Quantum Numbers
1. Principal Quantum Number ( n )
Energy level
Size of the orbital
n2 = # of orbitals in the energy level
Quantum Numbers
s p d f
2. Angular Momentum Quantum # ( l )
Energy sublevel
Shape of the orbital
Quantum Numbers
n = # of sublevels per level
n2 = # of orbitals per level
Sublevel sets: 1 s, 3 p, 5 d, 7 f
Quantum Numbers
3. Magnetic Quantum Number ( ml )
Orientation of orbital
Specifies the exact orbitalwithin each sublevel
C. Quantum Numbers
px py pz
C. Quantum Numbers
Orbitals combine to form a spherical shape.
2s
2pz2py
2px
Quantum Numbers
4. Spin Quantum Number ( ms )
Electron spin +½ or -½
An orbital can hold 2 electrons that spin in opposite directions.
Quantum Numbers
1. Principal # 2. Ang. Mom. # 3. Magnetic # 4. Spin #
energy level
sublevel (s,p,d,f)
orbital
electron
Pauli Exclusion Principle
No two electrons in an atom can have the same 4 quantum numbers.
Each e- has a unique “address”:
General Rules
Aufbau Principle
Electrons fill the lowest energy orbitals first.
“Lazy Student Rule”
General Rules
The Diagonal Rule
2p3p4p5p6p7p
3d4d5d6d
4f5f
2s3s4s5s6s7s
1s
8s
WRONGRIGHT
General Rules
Hund’s Rule
Within a sublevel, place one e- per orbital before pairing them.
“Empty Bus Seat Rule”
O
8e-
Orbital Diagram / Box & Arrow Diagram
Electron Configuration / SPDF Notation
1s2 2s2 2p4
Notation
1s 2s 2p
Shorthand Configuration
S 16e-
Valence Electrons
Core Electrons
S 16e- [Ne] 3s2 3p4
1s2 2s2 2p6 3s2 3p4
Notation
Longhand Configuration
© 1998 by Harcourt Brace & Company
sp
d (n-1)
f (n-2)
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Periodic Patterns
Periodic Patterns
Period # energy level (subtract for d & f)
A/B Group # total # of valence e-
Column within sublevel block # of e- in sublevel
s-block
1st Period
1s11st column of s-block
Periodic Patterns
Example - Hydrogen
1
2
3
4
5
6
7
Periodic Patterns
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.
[Ar] 4s2 3d10 4p2
Periodic Patterns
Example - Germanium
Full energy level
1
2
3
4 5
6
7
Full sublevel (s, p, d, f)Half-full sublevel
Stability
Electron Configuration Exceptions
Copper
EXPECT: [Ar] 4s2 3d9
ACTUALLY: [Ar] 4s1 3d10
Copper gains stability with a full d-sublevel.
Stability
Electron Configuration Exceptions
Chromium
EXPECT: [Ar] 4s2 3d4
ACTUALLY: [Ar] 4s1 3d5
Chromium gains stability with a half-full d-sublevel.
Stability
Stability
Ion Formation Atoms gain or lose electrons to become more
stable. Isoelectronic with the Noble Gases.
O2- 10e- [He] 2s2 2p6
Stability
Ion Electron Configuration
Write the e- config for the closest Noble Gas
EX: Oxygen ion O2- Ne
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