Title: Lesson 4 Full Electron Configuration Learning Objectives: Know how to write full electron configurations using ideas of subshells

1.1s 2 2s 2 2p 4 = Oxygen 2. 1s 2 2s 2 2s 6 3s 1 = Sodium 3. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 = Calcium 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. BELL TIME ACTIVITY

n th 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 2n 2 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!

1s 2 2s 2 3s 2 4s 2 5s 2 6s 2 7s 2 2p 6 3p 6 4p 6 5p 6 6p 6 3d 10 4d 10 5d 10 6d 10 4f 14 5f 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.

1s 2 2s 2 3s 2 2p 6 3p For example, Cl (#17) which is right here on the table: So the answer would be 1s 2 2s 2 2p 6 3s 2 3p 5 The short cut would be: [Ne]3s 2 3p 5

1s 2 2s 2 3s 2 4s 2 2p 6 3p 6 3d 8 4f 14 5f Or how about Ni (#28) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 8 Short cut: [Ar] 4s 2 3d 8

1s 2 2s 2 3s 2 4s 2 5s 2 6s 2 2p 6 3p 6 4p 6 5p 6 6p 3 3d 10 4d 10 5d 10 4f Let’s try Bi (#83) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 3 (don’t forget the 4f 14 !) Short cut: [Xe]6s 2 4f 14 5d 10 6p 3

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] 4s 1 [Ar] represents 1s 2 2s 2 2p 6 3s 2 3p 6

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.

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 2s 3s 1s atomic orbital. Density of dots gives the probability of finding the electron in this region. Atomic Orbitals

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

1.1s 2 2s 2 2s 6 3s 2 3p 6 4s 2 3d s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d s 2 2s 2 2p 6 3s 2 3p 6 4s 2 4d 10 Which electronic configuration for Zn, Zinc, is correct? BELL TIME ACTIVITY