Electron Arrangement
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Electron Arrangement
Atoms Review
Name the three particles of the atom and their respective charges are:
a. Proton positive
b. Neutron_ neutral, no charge
c. Electron negative
Atoms Review
The number of protons in one atom of an
element determines the atom’s
identity, and the number of electrons
determines the charge of an element.
Atoms Review
The atomic number tells you the number of protons in one atom of an element. It also tells you the number of electrons in a neutral atom of that element.
The atomic number gives the identity of an element as well as its location on the Periodic Table. No two elements will have the same atomic number.
Valence Electrons
Valence Electrons – are outer energy level electrons.
Label your periodic table with the number of valence
electrons in each group.
12 63 4 75
8
Lewis Structures
Electron Dot Diagrams Show the valence electrons
in an atom. EX: oxygen
O
X
Lewis Structures
Octet Rule Most atoms form bonds in order to obtain _8_ valence electrons Eight valence electrons means the atom has a full outer energy
level. A full outer energy level gives the atom stability. Group 18, the Noble Gases have full outer energy levels.
Learning Check
Where are the electrons in an atom located?
What number tells you the number of electrons in an atom?
What information do Lewis Dot Structures give you?
What is the octet rule?
Electron Configuration
Electrons in Atoms
Electron Configuration
The arrangement of electrons in an atom.
A distinct configuration exists for each atom.
Electron Configuration
Like all systems in nature, electrons in atoms tend to assume arrangements that have the lowest possible energies.
Ground State: the lowest energy arrangement of the electrons.
A. General Rules
Pauli Exclusion Principle
Each orbital can hold TWO
electrons with opposite spins.
A. General Rules
Aufbau Principle
Electrons fill the lowest energy orbitals first.
“Lazy Tenant Rule”
RIGHTWRONG
A. General Rules
Hund’s Rule
Within a sublevel, place one e- per orbital before pairing them.
“Empty Bus Seat Rule”
O
8e-
Orbital Diagram
Electron Configuration
1s2 2s2 2p4
B. Notation
1s 2s 2p
Shorthand Configuration
S 16e-
Valence Electrons
Core Electrons
S 16e- [Ne] 3s2 3p4
1s2 2s2 2p6 3s2 3p4
B. Notation
Longhand Configuration
© 1998 by Harcourt Brace & Company
sp
d (n-1)
f (n-2)
1234567
67
C. Periodic Patterns
C. 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
C. Periodic Patterns
Example - Hydrogen
1
2
3
4
5
6
7
C. 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
C. Periodic Patterns
Example - Germanium
Full energy level
1
2
3
4 5
6
7
Full sublevel (s, p, d, f)Half-full sublevel
D. Stability
Electron Configuration Exceptions
Copper
EXPECT: [Ar] 4s2 3d9
ACTUALLY: [Ar] 4s1 3d10
Copper gains stability with a full d-sublevel.
D. Stability
Electron Configuration Exceptions
Chromium
EXPECT: [Ar] 4s2 3d4
ACTUALLY: [Ar] 4s1 3d5
Chromium gains stability with a half-full d-sublevel.
D. Stability
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