Title: Lesson 4 Full Electron Configuration
Learning Objectives:
• Know how to write full electron configurations using ideas of subshells
BELL TIME ACTIVITY
Below are examples of how you write electron
configurations in HL chemistry. Try and figure out the
method used to produce them. Use your periodic table.
1. 1s22s22p4 = Oxygen
2. 1s22s22s63s1 = Sodium
3. 1s22s22p63s23p64s2 = Calcium
• nth energy level is divided into n sub levels
• s, p, d and f identify the different sub levels
• Each main level can hold a maximum of 2n2 electrons
Why?
Shows the existence of sub levels within an energy
level. This explains the behaviour of elements.
Draw out the sublevels in
each main energy level.
Starting at 1s, follow the
arrows to give the order
of the sublevels!
So, the pattern for reading the electron configurations right off the periodic table is this:
If you are wanting to write the electron configuration for any element, just follow this
pattern and remember to stop at the element you’re representing.
1
1s2
2
2s2
2p6
3
3s2
3p6
4
4s2
3d10
4p6
5
5s2
4d10
5p6
6
6s2
5d10
6p6
7
7s2
6d10
4f14
5f14
For example, Cl (#17) which is right here on the table:
So the answer would be 1s2 2s2 2p6 3s2 3p5
The short cut would be: [Ne]3s2 3p5
1
1s2
2
2s2
2p6
3
3s2
3p5
4
5
6
7
Or how about Ni (#28)
1s2 2s2 2p6 3s2 3p6 4s2 3d8
Short cut: [Ar] 4s2 3d8
1
1s2
2
2s2
2p6
3
3s2
3p6
4
4s2
3d8
5
6
7
4f14
5f14
Let’s try Bi (#83)
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6
6s2 4f14 5d10 6p3 (don’t forget the 4f14!)
Short cut: [Xe]6s2 4f14 5d10 6p3
1
1s2
2
2s2
2p6
3
3s2
3p6
4
4s2
3d10
4p6
5
5s2
4d10
5p6
6
6s2
5d10
6p3
7
4f14
Abbreviated electron Configurations
• Only outer electrons are shown
• Inner electrons are represented as a noble gas
core.
• After Argon (Ar), notation can be written like:
• Potassium = [Ar] 4s1
• [Ar] represents 1s22s22p63s23p6
The Uncertainty Principle
• Bohr’s model assumes the electron’s trajectory can be
precisely described = Not true.
• Any attempted measure of an electron’s position will
disturb the motion.
• Focusing radiation to locate an electron will give it a
‘kick’ throwing it into a random direction.
• We cannot know where an electron would be at any
given time – all we can give is a probability picture of
where the electron is likely to be.
Atomic Orbitals
By the way, the orbitals are not really little empty boxes on a line:
2p
Instead, they are specific three-dimensional shapes called probability
clouds that show where you are most likely to find the electron around
the nucleus.
The s sublevels are all spherical in shape:
And they just get larger and larger as you move to higher levels
1s atomic orbital. Density of
dots gives the probability of
finding the electron in this
region.
3s2s
1s
p Orbital
The p orbitals are a bit more complicated - they are peanut shaped!
Within the 2p sublevel, the three orbitals are oriented at right angles to each other.
They are referred to as the 2px, 2py and 2pz orbitals.
And they fit together around the nucleus like this:
P Orbitals
Complete the Test Yourself Questions
 Use the ‘Sub-levels of Electrons Table’ and ‘Electron
Configuration Blocks’ to help you
• Page 69
• Question 11 a-e
• Check your answers on page 559
BELL TIME ACTIVITY
Which electronic configuration for Zn,
Zinc, is correct?
1. 1s22s22s63s23p64s23d10
2. 1s22s22p63s23p64s23d10
3. 1s22s22p63s23p64s24d10