PERIODIC PROPERTIES
Nuclear Charge (z)
Effective N C (Zeff)
Ionization E
& Affinity
Trends on P. Table
Isoelectronic Series
Properties of Elements
EFFECTIVE NUCLEAR CHARGE
Zeff
nucleus & e- density of a many-e- atom
strength of attraction: 1) as magnitude of charges
2) distance from nucleus
3) L to R, slight down col
nucleus: 12 p+
inner core [Ne]: 10 evalence, 3s: 2 e-
12 – 10 = 2+
Shielding
Penetration
e- interaction; repulsion of e- consider orbital shapes
decr full nuclear charge, Zeff 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-
TREND -- Main Groups
ATOMIC SIZE
Incr L to R & down col
2 influences
1. es in E-levels
as E-levels, n, increase then also radius
2. Nucleus’ “+” charge, Zeff
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
Fig 7.6
pg 263
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
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 # elist ions incr atomic #; Zeff incr; results in ion radius decr
ex. pg 266 O-2 – F-1 – Na+1 – Mg+2 – Al+3
10 eeffect: incr Z as decr radius
Practice Problems
1)What is the As – I bond length in AsI3?
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
Min E required to remove e- from grd state to form cation
Li + E --- Li+1 + e-
Ca + E --- Ca+1 + eCa+1 + E -- Ca+2 + eI1 < I2 < I3 < etc
notice
balance
of charges
as I incr, more diff to remove e**drastic incr E remove inner core e-
Ionization Values
Table 7.2
pg. 268
Trends 1st Ionization E Values
Fig. 7.10
pg. 270
np4 e- easier to remove than np3
E required to remove eIEvalence shell e- < IEinner core eLi Z= 3 1s22s1
IE1= 520 kJ
valence e-
IE2= 7300 kJ
1st inner core e-
N Z=7 1s22s2p3
valence shell e- IE1 --> IE5
1402 kJ ---> 9440 kJ
inner core e- IE6 ---> IE7
53270 kJ ---> 64360 kJ
Thus w/ the greater E required to remove
inner core, those e- not involved in chem rxns
s
TREND,
Incr across
I1 row, decr down col
smaller atom I1 > larger atom I1
p
incr to ½-fill (3 e-), decr as remove from 1 pair, then incr
from s2 to p1, e- must enter empty subshell
p3 to p4; repulsion of pair, each p3 is single (ml)
Fig 7.12
pg 272
ELECTRON AFFINITY
E by addition of e- to grd state to form anion
Br + e- --- Br-1 + E
O + e- --- O-1 + E
O-1 + e- --- O-2 + E
-kJ/mol: indicates add e- is exo
+kJ/mol: E released when e- added
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 = EA1 < 0
EA2= “+” value
EA2 > EA1
Net Effect
• trend not as consistent as w/ IE
• typically decr down a col
• typically incr L--->R across row
usually
stronger attraction for e- > neg affinity value
+ value, e- not attached, ion unstable
p: incr across row; drop @ p3
p 1 < p2 < p4 < p5 < p6
p2 > p3 < p4
METALS - NONMETAL - METALLOIDS
ReVieW pg. 273
metals
shiny luster
malleable, ductile
conduct heat, elec
solid @ room temp
form + cations
metal oxides form bases
form alloys w/ metals
nonmetal
metalloid
no luster
have some metallic
not malleable, ductile
can conduct
poor conductors
-semiconductor
solids usually brittle
form - anions w/ metals
oxides form acids
form molecules w/ non
Incseasing Metallic Behavior
Fig 7.13
pg.274
GROUP TRENDS
IA - Alkali (ashes)
soft metals; metallic luster
low densities; low M.P.
down col I1 decr, radius incr, react incr
exist as cmpds only
alkali + H2 -------> Hyrdide LiH NaH
alkali + H2O ----> Base LiOH NaOH Ho = - EXO
form +1 cations
IIA - Alkaline
solids
compare to IA:
harder, more dense, higher M.P., reactive but less,
I2A > I1A
down col react incr
form +2 cation
NONMETALS
hYDroGeN
nonmetal, no group memeber
metallic under pressure
no shielding elarge I1 - 1300 as Li 500
H2 + non ----> Ho = - EXO
more in common w/ 7A
H2 + metal ----> Hydride NaH CaH2
OXYgen - 6A
only gas in group, all solids
O2 ----> O3 Ho = + ENDO
O3 < stable
OXYgen - 6A
down col M.P. & B.P. incr
diatomic molecules
high EA values, high to gain every soluble in H2O ----> hydro-hal-ic acid
HF
HCl
HBr HI
Noble Gases - 8A (inert; unreact)
nonmetals, monoatomic
complete filled s & p (s2p6)
LARGE
I1
ACID - BASE
Metals - Main
ME + O2 ----> OXIDE
2 Ca + O2 ----> 2 CaO
BEHAVIOR
Nonmetals
Ionic
ME oxide + H2O ----> BASE
CaO + H20 ----> Ca(OH)2
NM + O2 ----> OXIDE
S + O2 ----> SO2
Covalent
NM oxide + H2O ----> ACID
SO2 + H20 ----> H2SO3
Metalloids
form amphorteric subst.