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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.
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
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 So what is different?
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
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 1 7 2 5 8 Why will you never have more than eight dots?
Flame Tests Certain elements emit specific wavelengths of light when the electrons fall from outer energy levels back to their ground state.
H Hg Ne Line Spectra of Excited Atoms • Excited atoms emit light of only certain wavelengths • The wavelengths of emitted light depend on the element.