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FACT:. Chemical reactions happen because electrons are shared or transferred from one substance to another. MAX NUMBER OF ELECTRONS IN AN ENERGY LEVEL. Write a mathematical equation that allows us to predict the Max # if we know the energy level (n). Max # = …n….
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FACT: Chemical reactions happen because electrons are shared or transferred from one substance to another
Write a mathematical equation that allows us to predict the Max # if we know the energy level (n) Max # = …n…
Equation to calculate Max # of e- 2n2 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 Principle Quantum # The first number we already know… (a.k.a. The NRG level)
1st Quantum # Specifies the energy level that the electron is on Principle Quantum #
2nd Quantum # Specifies the shape of the sub-energy level
III. Quantum Mechanical Model: Atomic Orbitals E. Shapes of orbitals d orbitals
ORBITAL Space occupied by a pair of electrons
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
# of e- in sub-energy level Electron Configuration Symbols 5f3 Sub-Energy Level Energy Level
Bohr Models vs. e- Configs K K: 1s2 3s2 3p6 4s1 2p6 2s2
1s1 Write the e-config for: He: 1s2 Li: 1s22s1 H: K: 1s22s22p63s23p64s1
Valence Electrons Electrons in the outermost energy level (involved in chemical reactions)
K: 1s22s22p63s23p64s1 Noble Gas Shortcut 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?
3rd Quantum # Specifies the orientation of an orbital in space m or magnetic Q#
4th Quantum # Spin of an electron on its own axis s or spin Q#
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
What up? Bm 1 Who do 1 and 2 represent? 2 Why do 1 and 2 fill in on the same side?
What up? 3 6 Bm 4 Who do 3-8 represent? 7 5 8 Why do 3,4,5 and 6,7,8 fill in on different sides?
What up? 3 6 Bm 4 1 7 2 5 8 Why will you never have more than eight dots?
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!