Transcript Orbital Notation and Electron Configuration

Orbital Notation
and
Electron Configuration
October 20th
Distance From The Nucleus
 Called the Principle Quantum
Number (n)
 Describes the principle energy level
 n = 1, 2, 3
Shape of the Orbital
 Described by Orbital quantum
number (l)
 Tells you the shape of the orbital the
electron is in
 Is it an s, p, d, or f orbital?
Position in 3D Space
 Described by Magnetic Quantum Number (m)
 Indicated the position of the orbital around the 3
axes (x, y, z)
Electron’s Spin
 The direction of the electron’s spin is
described by the spin quantum number
 Electrons can be either up or down
 When electrons are part of a pair, they
must spin in opposite directions
Pauli Exclusion Principle
 No two electrons in the same atom can
have the same four quantum numbers
(the same description)
 No two electrons can have the same
address
 Electrons are repulsed by each other, so
they cannot live together… Hence
makes sense they have opposite spins!
Review Of Energy Levels
n=1
 s orbital (2 electrons)
n=2
 s orbital (2 electrons)
 p orbital (6 electrons)
n=3
 s orbital (2 electrons)
 p orbital (6 electrons)
 d orbital (10 electrons)
n=4
 s orbital (2 electrons)
 p orbital (6 electrons)
 d orbital (10 electrons)
 f orbital (14 electrons)
3 Rules for Electron Configuration
1) Aufbau Principle - electrons
occupy the orbitals of lowest
energy first
2) Pauli Exclusion Principle - no two
electrons can have the same
address(same 4 quantum #s)
3) Hund’s Rule - Electrons try to
occupy different orbitals before
pairing up
Orbital
Notation
order in which
electrons are
filled
The Order in which orbitals fill…
Orbital Notation
ORBITAL BOX NOTATION
for He, atomic number = 2
2
1s
1s
Arrows
depict
electron
spin
Arrangement of
Electrons in Atoms
 Each orbital can be assigned no more than 2
electrons!
 Each orbital can hold a pair of electrons per
orientation
s
1 orientation(pair)
2 electrons
p
3 orientations
6 electrons
d
5 orientations
10 electrons
f
7 orientations
14 electrons
Orbital Diagram
_____
1s
_____
2s
_____ _____ _____
2px 2py 2pz
_____
3s
_____ _____ _____
3px 3py 3pz
_____ _____ _____ _____ _____
3d
_____
4s
_____ _____ _____
4px 4py 4pz
_____ _____ _____ _____ _____
4d
_____
5s
_____ _____ _____
5px 5py 5pz
_____ _____ _____ _____ _____
5d
_____
6s
How Orbitals Fill….
_____
1s
_____
2s
_____ _____ _____
2px 2py 2pz
_____
3s
_____ _____ _____
3px 3py 3pz
Electron Configuration – Strontium
_____
1s
_____
2s
_____ _____ _____
2px 2py 2pz
_____
3s
_____ _____ _____
3px 3py 3pz
_____ _____ _____ _____ _____
3d
_____
4s
_____ _____ _____
4px 4py 4pz
_____ _____ _____ _____ _____
4d
_____
5s
_____ _____ _____
5px 5py 5pz
_____ _____ _____ _____ _____
5d
_____
6s
Valence electrons are electrons in the outermost
energy level of an atom.
Example: Sulfur
_____
1s
_____
2s
_____ _____ _____
2px 2py 2pz
_____
3s
_____ _____ _____
3px 3py 3pz
Valence electrons
Practice on your own!
 Draw the orbital diagram for Calcium
 Draw the orbital diagram for Silicon
Electron Configuration
for H, atomic number = 1
1 s
1
Energy Level
no. of
electrons
Subshell
(s, p, d, f)
Electron Configuration
 Fortunately! Its like orbital diagrams but
without drawing the orbitals…
 Fill electrons into lower energy levels first
 Follow order of filling
 Remember how many electrons each level can
hold: s holds 2, p holds 6, d 10, f 14
Examples
 Helium: 1s2
 Boron :
1s22s22p1
 Magnesium: 1s22s22p63s2
 Bromine: 1s22s22p63s23p64s23d104p5
Practice on your own!
Hydrogen
1s1
Sodium
1s22s22p63s1
Magnesium
1s22s22p63s2
Chlorine
1s22s22p63s23p5
Argon
1s22s22p63s23p6
Arsenic
1s22s22p63s23p64s23d104p3
Octet Rule
 Octet rule - all elements want to have a
full set of valence electrons
 Atoms will lose or gain electrons in
trying to achieve a full octet
Octet Rule
Octet Rule states that atoms will gain or
lose electrons to achieve a full outermost
energy level.
This is usually 8 electrons (s2 p6).
Example: Oxygen
_____
1s
_____
2s
O
_____ _____ _____
2px 2py 2pz