Download Quantum Mechanical Model(obj. 10-16)

Chemistry
Name :
Worksheet : Ch. 4-6 : Obj. 13-16
Date :
A. Quantum mechanical model of atoms :
- mathematical
- predicts the probability of electron locations and paths in electron clouds
- quanta (s. quantum) - energies required to raise an electron to a higher energy level
- or given off when electrons return to lower energy levels
- quanta are different
1. Energy states of electrons are described by four quantum numbers
a. Principle quantum number (n=1,2,3,4,5,6,or 7) - indicates energy level
b. Orbital quantum number - indicates the shape of the orbital the electron
occupies
- "atomic orbital" - region in space where there is a high probability of
finding an electron
- first four orbital quantum numbers : s,p,d,f
- orbital shapes : s - spherical shape
p - dumbbell-shaped
d and f - very complex shapes
P
r
i
n
c
i
p
l
e
e
n
e
r
g
y
l
e
v
e
lN
u
m
b
e
r
o
f
s
u
b
l
e
v
e
l
s
(
n
)
T
y
p
e
o
f
s
u
b
l
e
v
e
l
(
n
u
m
b
e
r
o
f
o
r
b
i
t
a
l
s
p
e
r
s
u
b
l
e
v
e
l
n
=
1
n
=
2
n
=
3
n
=
4
T
o
t
a
l
n
u
m
b
e
r
o
f T
o
t
a
l
n
u
m
b
e
r
o
f
2) e
2)
s
u
b
l
e
v
e
l
s
(
n
l
e
c
t
r
o
n
s
(
2
n
1
s
(
1
o
r
b
i
t
a
l
)
2
s
(
1
o
r
b
i
t
a
l
)
,2
p
(
3
o
r
b
i
t
a
l
s
)
3
s
(
1
o
r
b
i
t
a
l
)
,3
p
(
3
o
r
b
i
t
a
l
s
)
,3
d
(
5
o
r
b
i
t
a
l
s
)
4
s
(
1
o
r
b
i
t
a
l
)
,4
p
(
3
o
r
b
i
t
a
l
s
)
,4
d
(
5
o
r
b
i
t
a
l
s
)
,4
f
(
7
o
r
b
i
t
a
l
s
)
( Note : s orbitals can hold a maximum of 2 electrons, p orbitals can hold 6, d orbitals can hold 10, f orbitals
can hold 14)
c. magnetic quantum number - indicates position About the three axes (x,y,and
z) in space
d. spin quantum number - indicates direction of electron spin (clockwise or
counter clockwise)
Note : Each quantum position as described by the first three quantum numbers can be occupied by only two
electrons with opposite spins. (e.g. 2px or 3dy ).
2. Electron configuration : the arrangement of electrons around the nuclei of atoms
a. Three principles governing electron configuration :
i. Aufbau principle : electrons enter orbitals of the lowest energy first
help diagram :
1s
2s
3s
4s
5s
6s
7s
2p
3p
4p
5p
6p
7p
3d
4d
5d
6d
7d
4f
5f 5g
6f 6g
7f 7g
ii. Pauli exclusion principle : an atomic orbital may describe at most two
electrons ; electrons in the same orbital must have opposite spins
iii. Hund's rule : when electrons occupy orbitals of equal energy, one
electron enters each orbital until all the orbitals contain one
electron with parallel spins
Sample problems :
1. Show the electron configurations and then summarize the electron configurations of the following
elements:
Orbital :
___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___
Summary :
Hydrogen :
Helium :
Lithium :
Carbon :
Sodium :
Sulfur :
Argon :
Calcium :
2. Identify the following elements from their electron configurations :
2
2
2
2
2
2
___________________ 1s 2s
___________________ 1s 2s
___________________ 1s 2s
2
*___________________ 1s 2s
2
___________________ 1s 2s
2
2
6
2p
6
2p
6
2p
6
2p
6
2p
3s
3s
3s
3s
3s
1
2
2
2
2
3p
3p
6
6
6
3p
6
3p
4s
4s
4s
4s
2
2
1
2
5
3d
10
6
3d 4p
5
3d
3d
10
6
2
4p 5s 4d
10
3. Write the summary electron configuration for the following elements :
Iron (symbol Fe, at. No. 26)
Xenon (symbol Xe, at. No. 54)
6
2
5p 6s 4f
14
6
5d