PERIODIC PROPERTIES Nuclear Charge (z) Effective N C (Z eff ) Trends on P. Table Isoelectronic Series Properties of Elements Ionization E & Affinity

E FFECTIVE N UCLEAR C HARGE Z eff nucleus & e - density of a many-e - atom nucleus: 12 p + inner core [Ne]: 10 e - valence, 3s: 2 e - 12 – 10 = 2+ strength of attraction: 1) as magnitude of charges 2) distance from nucleus 3) L to R, slight down col

Shielding e- interaction; repulsion of e- decr full nuclear charge, Z eff Penetration consider orbital shapes i.e. 2p closer to nucleus, but 2s probable distr w/i 1s, therefore, 2s penetrates closer to nucleus Lower l value, more these e- penetrate Sublevel E order: s < p < d < f Effect of Nuclear Charge + nucleus e- attraction charge, then attraction pulls orbitals closer to nucleus more stable, more E required to remove e-

ATOMIC SIZE Incr L to R & down col TREND -- Main Groups 2 influences 1.  es in E-levels as E-levels, n, increase then also radius 2. Nucleus ’ “ + ” charge, Z eff as nucleus increases “ + ” chrg, draws E-levels in closer to nucleus, thus, decr radius IONS 1.1. anions > cations more “+” cation is smaller more “-” anion is larger 2. same charge cation; incr down col decr L to R 1A > 2A > 3A

SIZE nonbonding radius: closest dist separating nucleus of colliding atoms bonding radius: 1) attractive interaction bet atoms 2) atoms closer together than non-, 3) is dist that separates nuclei of bonded atoms Fig 7.6 pg 263 bonding radius < nonbonding radius trend bonding radius pg. 263 ion size depends on: cation radius < parent element anion radius > parent element

ISOELECTRONIC SERIES group of ions w/ same # e - list ions incr atomic #; Z eff incr ; results in ion radius decr ex. pg 266 O -2 – F -1 – Na +1 – Mg +2 – Al e - effect: incr Z as decr radius Practice Problems 1)What is the As – I bond length in As I 3 ? 2)Arrange in incr radius: F, P, S, As 3)What neutral element is isoelectronic to Al +3, Ti +4, Br -1 ? [As 1.19] + [I 1.33] = 2.52 Å F < S < P < As Ne, Ar, Kr

IONIZATION ENERGY Li + E ---  Li +1 + e - Min E required to remove e - from grd state to form cation I 1 < I 2 < I 3 < etc as I incr, more diff to remove e - **drastic incr E remove inner core e - Ca + E ---  Ca +1 + e - Ca +1 + E --  Ca +2 + e - notice balance of charges Ionization Values Table 7.2 pg. 268 Trends 1 st Ionization E Values Fig pg. 270

Li Z= 3 1s 2 2s 1 IE 1 = 520 kJ IE 2 = 7300 kJ valence e- 1 st inner core e- E required to remove e- IE valence shell e- < IE inner core e- N Z=7 1s 2 2s 2 p 3 valence shell e- IE 1 --> IE kJ ---> 9440 kJ inner core e- IE 6 ---> IE kJ ---> kJ np 4 e- easier to remove than np 3 Thus w/ the greater E required to remove inner core, those e- not involved in chem rxns

TREND, I 1 s Incr across row, decr down col smaller atom I 1 > larger atom I 1 incr to ½-fill (3 e - ), decr as remove from 1 pair, then incrp from s 2 to p 1, e - must enter empty subshell p 3 to p 4 ; repulsion of pair, each p 3 is single (m l )

ELECTRON AFFINITY  E by addition of e- to grd state to form anion Br + e  Br -1 + EO + e  O -1 + E O -1 + e  O -2 + E -kJ/mol: indicates add e - is exo +kJ/mol: E released when e - added Fig 7.12 pg 272

Net Effect trend not as consistent as w/ IE typically decr down a col typically incr L--->R across row EA 2 = “ + ” value EA 2 > EA 1 e- AFFINITY (EA) EA: E (kJ) required (released) to add 1 mol e- to 1 mol gaseous subst I (g) + e > I -1 (g) + E  E = EA 1 < 0 usually

stronger attraction for e- > neg affinity value + value, e - not attached, ion unstable p: incr across row; p 3 p 1 < p 2 < p 4 < p 5 < p 6 p 2 > p 3 < p 4

ReVieW pg. 273 no luster not malleable, ductile poor conductors solids usually brittle form - anions w/ metals oxides form acids form molecules w/ non metals nonmetal metalloid shiny luster malleable, ductile conduct heat, elec room temp form + cations metal oxides form bases form alloys w/ metals have some metallic can conduct -semiconductor METALS - NONMETAL - METALLOIDS Incseasing Metallic Behavior Fig 7.13 pg.274

GROUP TRENDS IA - Alkali (ashes) soft metals; metallic luster low densities; low M.P. down col I 1 decr, radius incr, react incr exist as cmpds only alkali + H > Hyrdide LiH NaH alkali + H 2 O ----> Base LiOH NaOH  H o = - EXO form +1 cations

IIA - Alkaline solids compare to IA: harder, more dense, higher M.P., reactive but less, I 2A > I 1A down col react incr form +2 cation NONMETALS H 2 + non ---->  H o = - EXO more in common w/ 7A H 2 + metal ----> Hydride NaH CaH 2 hYDroGeN nonmetal, no group memeber metallic under pressure large I as Li 500 no shielding e -

OXYgen - 6A only gas in group, all solids O > O 3  H o = + ENDO O 3 < stable down col M.P. & B.P. incr diatomic molecules high EA values, high to gain e- very soluble in H 2 O ----> hydro - hal - ic acid HF HCl HBr HI OXYgen - 6A

Noble Gases - 8A (inert; unreact) nonmetals, monoatomiccomplete filled s & p (s 2 p 6 ) LARGE I 1

Metals - Main ME + O > OXIDE Ionic 2 Ca + O > 2 CaO ME oxide + H 2 O ----> BASE CaO + H > Ca(OH) 2 ACID - BASE BEHAVIOR Metalloids form amphorteric subst. Nonmetals NM + O > OXIDE Covalent S + O > SO 2 NM oxide + H 2 O ----> ACID SO 2 + H > H 2 SO 3