For Mini-quiz 32

Pigeonhole 1 representation of electrons [Ar] 3d 4 4s 1 Cr + = As implied by Table + chemical reversal 4s 3d Pigeonhole representation D switch rule: s and d electrons in valence shell move around to produce filled, half-filled and/or empty orbitals in order to attain a more stable atom. Corrected for filled,half-filled, empty rule [ Ar]3d 5 4s 0 *This final moving around applies only for transition metals After fill, half-filled, empty correction 1 Called orbital diagrams in text [Ar]

d switch rule: s and d electrons in valence shell move around to produce filled, half- filled and/or empty orbitals in order to attain a more stable atom. If element only has s and p….it means no switching….

Write the correct, pigeonhole diagrams for the transition metal species below a) Cr b)Ni c)Ag + remember…rule is applied ONLY with the s & d electron combos (e.g. transition elements only) Write the correct, pigeonhole diagrams for the transition metal species below

What is the correct, abbreviated, d- switched configuration for Cu +1 ? A.[Ar] 4s 0 3d 10 B.[Ar] 3d 9 4s 1 C.[Ar] 4s 1 3d 10 D.[Ar] 3d 10 4s 0

electrons utterly rule how elements react to make compounds. What kind of electronic orbitals they possess decides how they behave chemically. s is for silly cow p is for pretty kitty d is for dumb dog Dogs drool, cats rule Why (really) the spdf song is sung…..

The specific combo of orbits creates the unique chemistry of an element Cl=[Ne]3s 2 3p 4 Be= [He]2s 2 100% cow33% cow+66% kitty Ti = [Ar] 3d 2 4s 2 50% cow +50% dog

What’s Periodic about the Periodic Table ?

Periodic Commonalities: halogens MP ( O C) BP ( O C) p mass Halogen chemistry !!! 2Na + X 2  2NaX (high melting white salts) X 2 (colored) + ethene  colorless dihalides Breathing X 2 kills you Chemistry= [inert gas] ns 2 np 5 X MP and BP very different So what’s common ???

Another example of periodic commonality inert (noble) gases p mass MP( o C) BP ( 0 C ) [Noble gas] chemistry= Core chemistry= So what’s common ??? NONE

A final example of `periodic commonality’: reactivities of alkali metals [inert gas] ns 1 chemistry SIZE (n) MATTERS ! Alkali metals It’s all about ….

A little addendum… Erwin Schrodinger (whiz kid) finally solves H atom to everyone’s satisfaction (in mid 1930s) with equation below* but only after the spectroscopists gave him the benchmarks to measure his predictions against…. “-h(  2  )/2m +  /r =E  obviously…(duh)” Schrodinger’s eigenvalue equation for one electron in 1/r electrostatic potential field= (H atom) No closed math form for general atoms yet “…. spectroscopists rule, you drool.” *

Where we’ve been so far on the chemistry bus trip…

Rutherford & Bohr ) Atomic structure & dimensions 2) p+n o, e - bookkeeping 3) Crazy quantum models Where we’ve been….

Mendeleev 1865 AD 1)Organizing element behavior to predict chemistry 2)Periodicity and the Periodic Table Where we’ve been ……

Where we’ve been…. In the land of the spectroscopists: ` fugetabout theory….let the line spectra rule or I breaka your face ! 1s 2 2s 2 2p 6 3s 2 3p 4 …… Describing atoms by electronic configurations implied by observation and predicted by Periodic table spectroscopy

Dalton 1805AD 1)Law of constant proportions 2)Law of multiple proportions Moles till we drop….. Where we’ve been…

“OK…so we know that water is H 2 O, salt is NaCl… Why don’t we ever see HO 2 and Na 2 C l … …and what holds H 2 O and NaCl together in the first place ?” Doc asks a few more of his dumb questions.

To answer Doc’s dumb questions we take a forced hike through several chemical bonding theories

Reading: Chapter 8 pp ionic model pp Lewis rules & covalent compounds pp exceptions pp formal charge, resonance pp VSEPR theory

CONDUCTIVITY DEMO…. HOW DO YOU KNOW A COMPOUND IS IONIC??? NaCl  If it lights up the light bulb, it’s ionic

Trends in binary ionic and near-ionic formulas LiCl Li 2 O Li 3 P NaCl Na 2 O Na 3 P KCl K 2 O K 3 P Trends down a column M a X b …all M’s combine the same for a given X

Trends in ionic and not ionic compound formulas Trend across columns MgCl 2 MgO Mg 3 P 2 HCl NaCl Na 2 O Na 3 P Al 2 O 3 AlP Is there a simple pattern here ?? CH4CH4 NH3NH3 H2OH2O

HINT #1: The Periodic Trend of Pauling’ Electronegativity (=electron suckativity) scale reveals a cliff… ???

HINT #2: the curious case of column

Noble gas chemistry 0 None Nada 8 What’s so curious ?? Noble…because like all aristocrats they have nothing to do with any of the lower class elements. The “Noble” Elements are utterly stable … …And what’s with this number 8 ??