# teaching material and questions .pdf - Module 4 Predict...

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Module 4Predict ground-state electron configurations for atoms and ions using the Aufbauprinciple, Hund’s rule, and the Pauli principleAufbau principle id s diagram that uses the electron configuration to predict theground state electrons.Electrons will prefer to be as close as possible to the nucleus to be at thelowest energy.As atoms have more electrons the additional electrons must occupy ahigher energy state which is further from the nucleus.This means that the orbitals with the lowest energy will be filled firstfollowed by the higher one.Ground state orbitals electrons will occupy the lowest principle energylevel availableEach energy level has a limited capacity for electrons.As each n goes up the energy level incresesn=3 this goes for 3s, 3p, 3d orbitals3s= l=0 m1= 03p =l=1m1=-1,0+13d= l=2 m1= -2,-1,0+1,+2n=2this goes for 2s and 2p orbitals2s= l=0 m1=02p l=1 m1=-1,0,+1n=1 would be 1s orbital and l=0 and m1=0No more than 2 electrons can occupy the same n, l, and m orbitalIf more electrons are needed it will move for exampleTo n=1 to n=2.Orbitals can have the same n andlvalue but have to have a different m1valve
Which are called degenerate orbitals.Pauli exclusion principleIn an atom or ion, no two electrons can have the same four quantumnumbers.The spin quantum number mshas values of +, -1212Only two electrons fit with the opposite spin.Hunds ruleIn hands rule the lowest energy orbital configuration from an atom withelectrons within a set of degenerate orbitals is having a maximum numberof unpaired electronsFor example, Nitrogen has 3 unpaired electrons in the 2p orbital1s22s22p3And forNe/ neon 1s22s22p6which the 2p has th maxim number of electrons.
Determine the number of valence and core electrons in atoms and ionsElectrons in all the subshells with the highest principal energy shell (n) alwaystend to have the lowest Z effectiveness and behave like valence electrons.Electrons that are low in energy shells, with higher z effective are called coreelectrons.One important factor is that is the way atoms behave chemically or physically isthe number of valance electrons.Electrons can shed them away or gain electrons to have a stable configurationwith full subshells.

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Term
Spring
Professor
vidensik
Tags
Pauli exclusion principle, Ccal, ground state electron configurations