Mpp presentations claudia_bernedo
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Transcript of Mpp presentations claudia_bernedo
C L A U D I A B E R N E D O
Electronic Structure
Ground State vs. Excited States
Electrons are normally in their ground When they absorb energy, they get promoted to
excited states. Excited states are higher in energy than ground
states. Excited states come back down to the ground state
via release of energy.
Quantum Numbers
Electron address Principal quantum number ‘n’: designates which
shell the electron Sublevel ‘l’: designates subshell (s,p,d,f) l: n-1 Magnetic quantum number ‘ml’: designates precise
orbital of the subshell. –l to +l Spin + or -
Geometric Shapes
Rules
Heisenberg Uncertainty Principle: The more we know about the momentum of any particle, the less we know about the position.
Pauli Exclusion Principle: no two electrons in same atom can have same four quantum numbers.
Aufbau Principle: shells and subshells of lower energy gets filled first
Hund’s Rule: electrons will not fill any orbital in the same subshell until all orbitals in that subshell contain at least 1 electron
Bohr atom
Electron orbiting the nucleus in a circular orbit. Larger n values have larger orbiting radii.
Effective nuclear Charge
Effective nuclear charge = nuclear charge - shielding electrons. Shielding electrons are those that stand between the nucleus and the
electron we are interested in. Shielding electrons are those that are in subshells closer to the
nucleus (lower in energy) than the electron we are interested in. MCAT questions usually give you a diagram of the Bohr model, in
which case, shielding electrons are those that orbits at a smaller radius.
The higher the effective nuclear charge for an electron, the more stable it is (higher ionization energy, not easily knocked off).
Effective nuclear charge increases for outer electrons as you go across (left to right) the periodic table.
Questions
1. Which of the following is the correct electron configuration for the bromide ion, Br-?
a) [Ar] 4s24p5
b) [Ar] 4s23d104p5
c) [Ar] 4s23d104p6
d) [Ar] 4s23d104p65s1
e) [Ar] 4s23d103p6
Questions
1. Which orbital cannot exist? a)2p b)3p c)4d d)3f