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Unformatted text preview: 8 Out-line Development of PT Periodic Law- ele exhibit reaccurance of similar properties when org by atomic mass (now atomic #) Characteristics of many-ele atoms The e- spin Quantum # Describes spin of e-, = either -.5 or +.5, intristic property, N= orb nrg (size) L= (0 to n-1) orb shape Ml= (-1,0,1) orb orientation Ms= spin The exclusion principle No two e- in the same atom can have the same 4 #s Electrostatic Effects and Nrg-level Splitting All sublevels of a given level have the same nrg Consequence- the splitting of nrg levels into sublevels of differing nrgs: the nrg orb in a many-e- atom depends on n value (to a lesser extent the l value) Nrg differences is bc nuc charge, e- repulsions, orb shape which leads to shielding and penetration The affect of Nuc charge (Z) on Orb Nrg Higher charges attract more than lower charges higher nuc charge = lower orb charges by inc nuc-e- attractions Shielding: The effect of E- Repulsions on Orb nrg Shielding reduces full nuc charge to effective nuc charge (the nuc charge an e- actually experiences) Lower nuc charge= easier e- removal Greater shielding by inner e-s bc they spend nearly all time in btwn outer e- and nuc which greatly lowers Zeff felt by outer e-s Penetration: The effect of Orb shape on Orb nrg Penetration- outer e- moves through region of core e-s to spend more time closer to nuc, inc ave effective nuc charge for that e- Penetration and the resulting effects on shielding cause an nrg level to split into sublevels of diff nrg S<p<d<f The Quantum-Mechanical Model and the PT E config is the basis for recurring chem behavior Building up Periods 1 and 2 Aufbau Principle ground-st config Two Common ways to designate orb and its e- 1. the e- config- (n value)(l value)(# of e-) 2. The orb diagram- box with up (+ .5) or down (-) arrow. Each box only contains 2 e- and the nrg of the sublevels inc from l to r Hunds rule- when orbs of = nrg are available, the e- config of the lowest nrg has the max # of unpaired e-s with parallel spins Building up Period 3 Condensed E- config = Noble gas then finish E- Config within Groups Orbs are filled in order of inc nrg, which leads to outer e- config the...
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