Transcript Chemistry Notes - Washington High School

Electron
Configuration
Notes
• Ground State –
The lowest energy state of an atom.
• Excited State –
State in which an atom has a higher
potential energy then it has in its ground
state.
• Heisenberg Uncertainty Principle –
It is impossible to determine
simultaneously both the position and
velocity of an electron or any other
particle. (Can’t exactly predict where
electrons will be, just give a general idea.)
• Orbital –
Three dimensional region around the
nucleus that indicates the probable
location of an electron.
• Quantum Numbers –
Numbers that specify the properties of
atomic orbital’s and the properties of
electrons in orbital’s.
• Principle Quantum Number –
(n) The main energy level occupied by the
electron.
– Positive numbers only  1, 2, 3, etc
• Angular Momentum Quantum Number –
(l) The shape of the orbital.
– Starts at 0 and then positive integers till n – 1
is reached
• Ex. If n = 2, then l = 0, 1
• Ex. If n = 4, then l = 0, 1, 2, 3
Orbital Letter Designations
l
Letter
0
s
1
p
2
d
3
f
• Magnetic Quantum Numbers –
(m) The orientation of an orbital around the
nucleus.
– Starts at –l and it each integer to l
• Ex. If l = 2, then m = -2, -1, 0, 1, 2
• Ex. If l = 3, then m = -3, -2, -1, 0 , 1, 2, 3
• Ex. If n = 5, then l = 0, 1, 2, 3, 4,
then m = -4, -3, -2, -1, 0, 1, 2, 3, 4
• Spin Quantum Number –
Indicate the two fundamental spin states of
an electron in an orbital.
– Can only be + ½ or – ½
Quantum Number Relationships in Atomic Structure
Principle
Quantum
Number
(Main
Energy
Level)
Sublevels
In Main
Energy
Level
1
s
1
s
1
p
3
s
1
p
3
d
5
10
s
1
2
p
3
6
d
5
f
7
2
3
4
Number of
Number of
Number of
Orbital’s per
Orbital’s per
Electrons
Main Energy
Sublevel
per Sublevel
Level
1
4
2
2
6
Number of
Electrons
per Main
Energy
Level
2
8
2
9
16
6
10
14
18
32
• Electron Configuration –
The arrangement of electron’s in an atom.
• Aufbau Principle –
An electron occupies the lowest energy orbital that
can receive it.
• Pauli Exclusion Principle –
No two electrons in the same atom can have the same
set of four quantum numbers.
• Hunds Rule –
Orbital’s of equal energy are each occupied by one
electron before any orbital is occupied by a second
electron.
1s2
2s2
2p6
3s2
3p6
4s2
3d10
4p6
5s2
4d10
5p6
6s2
4f14
5d10
6p6
7s2
5f14
6d10
Orbital Sample 1
• The electron configuration of boron is
1s22s22p1. How many electrons are
present in an atom of boron? What is the
atomic number of boron? Write the orbital
notation for boron.
Number of electrons =
super scripts added together
• Number of electrons = 2 + 2 + 1
• Number of electrons = 5
Atomic Number = look on PT
• Atomic Number = 5
Orbital Notation = ___
1s
___
2s
___
2px
___
2py
___
2pz
• Start with the first orbital…
___
1s
___
2s
___
2px
___
2py
___
2pz
___
2py
___
2pz
• Move onto the next orbital…
___
1s
___
2s
___
2px
• According to Hunds rule, we have to fill each orbital of
the 2p level with one electron first, then go back and fill
with the second electron…
___
1s
___
2s
___
2px
___
2py
___
2pz
Orbital Sample 2
The electron configuration of nitrogen is
1s22s22p3. How many electrons are
present in a nitrogen atom? What is the
atomic number of nitrogen? Write the
orbital notation for nitrogen.
Number of electrons =
super scripts added together
• Number of electrons = 2 + 2 + 3
• Number of electrons = 7
Atomic Number = look on PT
• Atomic Number = 7
Orbital Notation = ___
1s
___
2s
___
2px
___
2py
___
2pz
• Start with the first orbital…
___
1s
___
2s
___
2px
___
2py
___
2pz
___
2py
___
2pz
• Move onto the next orbital…
___
1s
___
2s
___
2px
• According to Hunds rule, we have to fill each orbital of
the 2p level with one electron first, then go back and fill
with the second electron…
___
1s
___
2s
___
2px
___
2py
___
2pz
Orbital Sample 3
The electron configuration of fluorine is
1s22s22p5. What is the atomic number of
fluorine? How many of its p orbital’s are
filled? How many unpaired electrons
does a fluorine atom contain?
Atomic Number = look on PT
• Atomic Number = 9
How many of its p orbital’ are filled =
___
___
___ ___ ___
1s
2s
2px 2py 2pz
How many of its p orbital’s are filled = 2
How many unpaired electrons does a
fluorine atom contain = 1
• Octet of Electrons –
When the s and p orbital’s are filled.
Octet = 8
s orbital = 2 + p orbital = 6
2+6=8
• Nobel Gas –
The group 18 elements. No unpaired
electrons and all orbital’s of the energy
level are full.
E- Config. Sample 1
Write both the complete electronconfiguration notation and the noble-gas
notation for iron, Fe.
Write the complete electron-configuration
notation…
• Figure out number of electrons
In a stable atom, number of protons =
number of electrons
Fe = 26
• Start writing electron configuration till
number of electrons is reached
1s2 2s2 2p6 3s2 3p6 4s2 3d6
Write the noble-gas notation…
• Find the highest filled p orbital and its
Noble gas
3p6 = Ar
• Write the noble gas in brackets and then
the remainder of the full electron
configuration
[Ar] 4s23d6
E- Config. Sample 2
Write both the complete electron
configuration notation and the noble-gas
notation for iodine, I.
Write the complete electron-configuration
notation…
• Figure out number of electrons
In a stable atom, number of protons =
number of electrons
I = 53
• Start writing electron configuration till
number of electrons is reached
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10
5p5
Write the noble-gas notation…
• Find the highest filled p orbital and its
Noble gas
4p6 = Kr
• Write the noble gas in brackets and then
the remainder of the full electron
configuration
[Kr] 5s24d105p5
E- Config. Sample 3
Without consulting the periodic table or a
table in this chapter, write the complete
electron configuration for the element with
atomic number 25.
Write the complete electron-configuration
notation…
• Figure out number of electrons
Given 25
• Start writing electron configuration till
number of electrons is reached
1s2 2s2 2p6 3s2 3p6 4s2 3d5