FACT: Chemical reactions happen because electrons are shared or transferred from one substance to another
MAX NUMBER OF ELECTRONS IN AN ENERGY LEVEL MAX # OF ELECTRONS 1 2 8 3 18 4 32 5 50
Write a mathematical equation that allows us to predict the Max # if we know the energy level (n) Max # = …n… ENERGY LEVEL MAX # OF ELECTRONS 1 2 8 3 18 4 32 5 50
Equation to calculate Max # of e- Where n is any energy level
There are 4 Quantum #s and those #s are used to describe where an electron is likely to be found at any given time
This is a lot like being able to use four “places” to describe EXACTLY where Mr. T should be at 8:00AM on Friday.
The first number we already know… The Principle Quantum # (a.k.a. The NRG level)
Specifies the energy level that the electron is on 1st Quantum # Principle Quantum # Specifies the energy level that the electron is on
Principle Quantum # (IDEA Academy’s Street)
Specifies the shape of the sub-energy level 2nd Quantum # Specifies the shape of the sub-energy level
s and p Sub Energy Levels
III. Quantum Mechanical Model: Atomic Orbitals E. Shapes of orbitals d orbitals
Space occupied by a pair of electrons ORBITAL Space occupied by a pair of electrons
Four Sub-Energy Levels Sub NRG Level Shape Max # of electrons # of Orbitals s Sphere 2 1 p Dumbbell 6 3 d 4-Lobed 10 5 f 6-8 Lobed 14 7
Sub-Energy Levels
So why do electrons fill in like they do? i.e. why is K’s last electron in the 4th NRG level?
2 Factors Influencing Electron Placement Energy Level - Closer to nucleus=easy 2. Subenergy level (shape) - spdf
Electron Configuration A detailed way of showing the order in which electrons fill in around the nucleus
Electron Configuration Symbols # of e- in sub-energy level 5f 3 Sub-Energy Level Energy Level
Electron Configuration PT
Bohr Models vs. e- Configs K K: 1s2 2s2 2p6 3s2 3p6 4s1
Write the e- config for: 1s1 He: 1s2 Li: 1s22s1 K: 1s22s22p63s23p64s1
Valence Electrons Electrons in the outermost energy level (involved in chemical reactions)
Noble Gas Shortcut K: 1s22s22p63s23p64s1 K: [Ar] 4s1
Aufbau Principle All lower energy sublevels must be full before high energy sublevels begin filling in
Steps for writing NGSC Write the noble gas preceding the desired element [in brackets] Carry on as usual
With only the first two Quantum #s, do we have as much information as possible as to where the electrons are likely to be found?
Specifies the orientation of an orbital in space 3rd Quantum # m or magnetic Q# Specifies the orientation of an orbital in space
Spin of an electron on its own axis 4th Quantum # s or spin Q# Spin of an electron on its own axis
Quantum Review 1st Q#: Energy Level 2nd Q#: Shape of sub 3rd Q#: Orientation of Orbital 4th Q#: Spin of e-
Quantum Review Principle (n): 1, 2, 3, 4, … Azimuthal (l): 0, 1, 2, 3 Magnetic (ml): …-2, -1, 0, 1, 2 Spin (ms): +1/2 or -1/2
Pauli Exclusion Principle No 2 electrons can have the same set of 4 quantum numbers
Arrow-Orbital Diagrams A way to show orbital filling, spin, relative energy
Hund’s Rule Most stable arrangement of electrons is the one with the maximum number of unpaired electrons
Arrow-Orbital Diagrams Energy 3d 4s 3p 3s 2p 2s 1s
Lewis Electron Dot Diagrams The easiest way to represent the # of valance electrons
Steps for writing electron dot diagrams Write the element’s symbol Write out e- config Count # of valence e-s (1-8) Place same # of dots as e- around symbol
Order to fill in an e- dot 3 6 Bm 4 1 7 2 5 8
Why do 1 and 2 fill in on the same side? What up? Bm 1 Who do 1 and 2 represent? 2 Why do 1 and 2 fill in on the same side?
Why do 3,4,5 and 6,7,8 fill in on different sides? What up? 3 6 4 Bm Who do 3-8 represent? 7 5 8 Why do 3,4,5 and 6,7,8 fill in on different sides?
Why will you never have more than eight dots? What up? 3 6 4 Bm 1 7 2 5 8 Why will you never have more than eight dots?
Examples of Lewis Electron Dots
Our way accounts for Quantum #s, this way doesn’t! What is different between the dot diagrams below and the ones that we’ve been doing? Our way accounts for Quantum #s, this way doesn’t!