CHE 106 Prof. J. T. Spencer 1 Chapter Seven: Periodicity v Periodic Table - Organizes many “facts” and trends in chemical reactivity v Based upon electronic

CHE 106 Prof. J. T. Spencer 1

Chapter Seven: PeriodicityChapter Seven: PeriodicityChapter Seven: PeriodicityChapter Seven: Periodicity

Periodic Table - Organizes Periodic Table - Organizes many “facts” and trends in many “facts” and trends in chemical reactivitychemical reactivity

Based upon electronic Based upon electronic configurations of the elementsconfigurations of the elements

Similarities in electronic Similarities in electronic properties leads to similarities properties leads to similarities in chemical reactivity and in chemical reactivity and structurestructure

Copyright J. T. Spencer 1995 - 1997


Chapter Seven: PeriodicityChapter Seven: PeriodicityChapter Seven: PeriodicityChapter Seven: Periodicity

Element - Element - a substance that cannot be a substance that cannot be decomposed into simpler substances decomposed into simpler substances by chemical or physical meansby chemical or physical means..

Most elements not found in nature in Most elements not found in nature in “elemental” form but in combination “elemental” form but in combination with other elements (particularly H with other elements (particularly H or O) in the form of mineralsor O) in the form of minerals

Prior to 1800, 31 elements known Prior to 1800, 31 elements known (mostly those that were found in (mostly those that were found in elemental form in nature (i.e., gold, elemental form in nature (i.e., gold, silver, nitrogen, etc...).silver, nitrogen, etc...).


Periodic Table Periodic Table DevelopmentDevelopmentPeriodic Table Periodic Table DevelopmentDevelopment

Between 1800 and 1865, 32 more were Between 1800 and 1865, 32 more were isolated by improved chemical techniques.isolated by improved chemical techniques.

Dmitri Mendeleev - noted that chemical and Dmitri Mendeleev - noted that chemical and physical properties recur periodically when physical properties recur periodically when the elements are arranged in order of the elements are arranged in order of increasing atomic weight. (atomic number increasing atomic weight. (atomic number not known then although atomic weights not known then although atomic weights generally follow atomic number sequence)generally follow atomic number sequence)

When he created the table, he was forced When he created the table, he was forced to leave blank spaces for “undiscovered” to leave blank spaces for “undiscovered” elements but he correctly predicted many elements but he correctly predicted many of their properties by use of his table.of their properties by use of his table.


Mendeleev’s GuessesMendeleev’s GuessesMendeleev’s GuessesMendeleev’s Guesses

Mendeleev’s guesses Mendeleev’s guesses Observed Observed for Ge (1871) for Ge (1871)

properties properties for Ge (1886)for Ge (1886)

Atomic WeightAtomic Weight 7272 72.5972.59DensityDensity 5.55.5 5.355.35Specific Heat (J/gK)Specific Heat (J/gK) 0.3050.305 0.3090.309Melting Point (°C)Melting Point (°C) HighHigh 947947Oxide FormulaOxide Formula XOXO22 GeOGeO22

Density of Oxide Density of Oxide 4.7 g/cm4.7 g/cm33 4.70 4.70 g/cmg/cm33

Chloride FormulaChloride Formula XClXCl44 GeClGeCl44

Chloride b.p. (°C)Chloride b.p. (°C) <100<100 8484

Guesses for Ge based upon Periodic TrendsGuesses for Ge based upon Periodic Trends

Table in TEXT


Mendeleev’s GuessesMendeleev’s GuessesMendeleev’s GuessesMendeleev’s Guesses

Mendeleev’s guesses Mendeleev’s guesses Observed Observed for Ge (1871) for Ge (1871)

properties properties for Ge (1886)for Ge (1886)

Atomic WeightAtomic Weight 7272 72.5972.59DensityDensity 5.55.5 5.355.35Specific Heat (J/gK)Specific Heat (J/gK) 0.3050.305 0.3090.309Melting Point (°C)Melting Point (°C) HighHigh 947947Oxide FormulaOxide Formula XOXO22 GeOGeO22

Density of Oxide Density of Oxide 4.7 g/cm4.7 g/cm33 4.70 4.70 g/cmg/cm33

Chloride FormulaChloride Formula XClXCl44 GeClGeCl44

Chloride b.p. (°C)Chloride b.p. (°C) <100<100 8484

Guesses for Ge based upon Periodic TrendsGuesses for Ge based upon Periodic Trends

Table in TEXT


Periodic DevelopmentPeriodic DevelopmentPeriodic DevelopmentPeriodic Development

Moseley (1887-1915) discovered Moseley (1887-1915) discovered atomic number concept (atomic atomic number concept (atomic number = number or protons and number = number or protons and electrons in an atom) from assigning electrons in an atom) from assigning X-ray from the elements.X-ray from the elements.

Periodic Table:Periodic Table:– column or column or groupsgroups (increasing n, (increasing n,

principal quantum numberprincipal quantum number, on , on descendingdescending

GGrroouupp

PeriodPeriod


Periodic TablePeriodic TablePeriodic TablePeriodic Table

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

1H 2He

3Li 4Be 5B 6C 7N 8O 9F 10Ne

11Na 12Mg 13Al 14Si 15P 16S 17Cl 18Ar

19K 20Ca 21Sc 22Ti 23V 24Cr 25Mn 26Fe 27Co 28Ni 29Cu 30Zn 31Ga 32Ge 33As 34Se 35Br 36Kr

37Rb 38Sr 39Y 40Zr 41Nb 42Mo 43Tc 44Ru 45Rh 46Pd 47Ag 48Cd 49In 50Sn 51Sb 52Te 53I 54Xe

55Cs 56Ba 57La 72Hf 73Ta 74W 75Re 76Os 77Ir 78Pt 79Au 80Hg 81Tl 82Pb 83Bi 84Po 85At 86Rn

87Fr 88Ra 89Ac 104Unq 105Unp 106Unh 107Ns 108Hs 109Mt

58Ce 59Pr 60Nd 61Pm 62Sm 63Eu 64Gd 65Tb 66Dy 67Ho 68Er 69Tm 70Yb 71Lu

90Th 91Pa 92U 93Np 94Pu 95Am 96Cm 97Bk 98Cf 99Es 100Fm 101Md 102No 103Lr

s orbitalss orbitals

p orbitalsp orbitals

d orbitalsd orbitals

f orbitalsf orbitals

closed shellclosed shell

3d3d3d3d

4d4d4d4d

5d5d5d5d

6d6d6d6d

2s2s2s2s

3s3s3s3s

4s4s4s4s

5s5s5s5s

6s6s6s6s

7s7s7s7s

2p2p2p2p

3p3p3p3p

4p4p4p4p

5p5p5p5p

6p6p6p6p

4f4f4f4f

5f5f5f5f


““Electron Shells”Electron Shells”““Electron Shells”Electron Shells”

Electrons with same principal energy value are in Electrons with same principal energy value are in the same “shell”.the same “shell”.

Why is the Ar n = 1 closer than n = 1 Ne or He? Why is the Ar n = 1 closer than n = 1 Ne or He? SCREENINGSCREENING!!

22 (rad)(rad)

Distance from NucleusDistance from Nucleus

ArAr

NeNe

HeHe

Helium showed 1 shell (n = 1)Helium showed 1 shell (n = 1)Neon showed 2 shells (n = 1,2)Neon showed 2 shells (n = 1,2)

Argon showed 3 shells ( n= 1,2,3)Argon showed 3 shells ( n= 1,2,3)


In many electron atoms, electron-electron In many electron atoms, electron-electron repulsions become more important than repulsions become more important than electron-nuclear attractions.electron-nuclear attractions.

Estimate the energy of an electron in an orbital Estimate the energy of an electron in an orbital by considering how it, on the average, interacts by considering how it, on the average, interacts with its electronic environment (treat electrons with its electronic environment (treat electrons individually).individually).

The net attractive force that an electron will feel The net attractive force that an electron will feel is the is the effective nuclear chargeeffective nuclear charge (Z (Zeffeff).).

ZZeffeff = Z - S = Z - S Screening is the average number of other Screening is the average number of other

electrons that are between the electron and the electrons that are between the electron and the nucleus.nucleus.

Screening (Shielding)Screening (Shielding)Screening (Shielding)Screening (Shielding)

Z = nuclear chargeS = screening valueZ = nuclear chargeS = screening value


Screening (Shielding)Screening (Shielding)Screening (Shielding)Screening (Shielding)

rr

Average electronic charge (S) between the nucleus and the electron of interest

Electrons outside of sphere of radius r have very little effect

on the effective nuclear charge experienced by the electron at

radius r

Zeff = Z - S

ZZ

The larger The larger the Zthe Zeffeff an an

electron electron feels leads feels leads to a lower to a lower energy for energy for

the electronthe electron


Atomic SizesAtomic SizesAtomic SizesAtomic Sizes

Atoms as hard spheres vs. quantum Atoms as hard spheres vs. quantum mechanical picture without sharply mechanical picture without sharply defined boundaries. (electron defined boundaries. (electron density does not abruptly stop)density does not abruptly stop)

Estimate atomic radii by assuming Estimate atomic radii by assuming that atoms are spheres that “touch” that atoms are spheres that “touch” when bonded together in molecules. when bonded together in molecules.

Atomic radii are approx. constant Atomic radii are approx. constant when an atom is bonded in many when an atom is bonded in many compounds.compounds.


Atomic RadiiAtomic RadiiAtomic RadiiAtomic Radii

Periodic TablePeriodic Table

Radius IncreasesRadius Increases

2r2r

1. Radii 1. Radii increase increase

from top to from top to bottom within a bottom within a

groupgroup2. Radii 2. Radii

increase in increase in moving R to L moving R to L

within a periodwithin a period

Molecule Bond Distance (pm)H2 74 pmF2 272 pmC-C 154 pmCH 114 pmCF 213 pm


For Outer electron:For Outer electron:Boron; ZBoron; Zeffeff (approx.) = 5 - 4 = 1 nuclear charge (approx.) = 5 - 4 = 1 nuclear charge

Carbon; ZCarbon; Zeffeff (approx.) = 6 - 4 = 2 nuclear charges (approx.) = 6 - 4 = 2 nuclear charges

Nitrogen; ZNitrogen; Zeffeff (approx.) = 7 - 4 = 3 nuclear charges (approx.) = 7 - 4 = 3 nuclear charges

Fluorine; ZFluorine; Zeffeff (approx.) = 9 - 4 = 5 nuclear charges (approx.) = 9 - 4 = 5 nuclear charges

Why does radius decrease across a Why does radius decrease across a group?group?– Nuclear charge increases while Nuclear charge increases while

screening does not increase.screening does not increase.



Radius IncreasesRadius Increases 2p electrons DO NOT 2p electrons DO NOT screen each other screen each other while the 2s very while the 2s very effectively screen the effectively screen the 2p, also each element 2p, also each element to right adds +1 to to right adds +1 to nucleus.nucleus.



Li < Na < K < Rb < Cs, due to increasing n Li < Na < K < Rb < Cs, due to increasing n values.values.

Li > F because of ZLi > F because of Zeffeff changes. changes.

LiLiNaNa

KKRbRb

FF ClCl BrBr II

AtomicAtomicRadiusRadius

(Å)(Å)

Atomic NumberAtomic Number

TransitionMetals

TransitionMetals

1010 20 20 30 30 40 40 50 50


Atomic Sizes: Charge Atomic Sizes: Charge EffectsEffectsAtomic Sizes: Charge Atomic Sizes: Charge EffectsEffects

Fe Fe (232 pm)(232 pm)

FeFe+2 +2

(152 pm)(152 pm)FeFe+3 +3

(128 pm)(128 pm)

FF(128 pm)(128 pm)

F F -1 -1

(272 pm)(272 pm)Li Li

(304 pm)(304 pm)LiLi++

(120 pm)(120 pm)



Sample exercise: Predict which will be greater, the P-Br bond length in PBr3 or the As-Cl bond length in AsCl3.




PBr3 P - 1.06Br - 1.14

Length: 2.20




PBr3 P - 1.06Br - 1.14

Length: 2.20

AsCl3 As - 1.19Cl - 0.99

Length: 2.18



Sample exercise: Arrange the following atoms in order of increasing atomic radius: Na, Be, Mg




- radius decreases as you go across the period, increases as you go down the group.









Be < Mg < Na


Ionization Energy (IE)Ionization Energy (IE)Ionization Energy (IE)Ionization Energy (IE)

Electrons are “exchanged” in many chemical Electrons are “exchanged” in many chemical reactions. [i.e., A gives electron(s) to B]reactions. [i.e., A gives electron(s) to B]

Ionization EnergyIonization Energy (IE) measures how strongly an (IE) measures how strongly an atom holds on to its electrons (atom holds on to its electrons (the minimum energy the minimum energy necessary to remove an electron from the ground necessary to remove an electron from the ground state of an isolated gaseous atomstate of an isolated gaseous atom).).

Higher ionization processes are possible:Higher ionization processes are possible:

– first IE - remove 1st electron; first IE - remove 1st electron; AA AA+1+1 + e + e--

– second IE - remove 2nd electron;second IE - remove 2nd electron; AA+1+1

AA+2+2 + e + e--

– third IE - remove 3rd electron;third IE - remove 3rd electron; AA+2+2 AA+3+3 + e + e--

E(g)E(g) EE+1+1(g) + 1 e(g) + 1 e--


Ionization EnergiesIonization EnergiesIonization EnergiesIonization Energies II11 < I < I22 < I < I33 (increasing positive charge on atom). (increasing positive charge on atom). Very sharp increase in IE when an inner shell Very sharp increase in IE when an inner shell

(core) electron is removed.(core) electron is removed. Within each period, IWithin each period, I11, generally increases with , generally increases with

increasing atomic number (increasing Zincreasing atomic number (increasing Zeffeff).). Within each group, IE generally decreases with Within each group, IE generally decreases with

increasing atomic number (“bigger” atoms).increasing atomic number (“bigger” atoms).


1st IE Increases1st IE Increases


Ionization Energies (IE)Ionization Energies (IE)Ionization Energies (IE)Ionization Energies (IE)

HH (1s (1s11))

HeHe (1s (1s22))


1st IE1st IE(kJ/mol)(kJ/mol)



HH (1s (1s11))

HeHe (1s (1s22))

Li Li (1s(1s222s2s11))





HH (1s (1s11))

HeHe (1s (1s22))

Li Li (1s(1s222s2s11))


1st IE1st IE(kJ/mol)(kJ/mol) BeBe (1s (1s222s2s22))



HH (1s (1s11))

HeHe (1s (1s22)) (1s(1s222s2s222p2p66) ) NeNe

Li Li (1s(1s222s2s11))


1st IE1st IE(kJ/mol)(kJ/mol) BeBe (1s (1s222s2s22))

BB (1s (1s222s2s222p2p11))

C C (1s(1s222s2s222p2p22))

(1s(1s222s2s222p2p33) ) NN

O O (1s(1s222s2s222p2p44))

F F (1s(1s222s2s222p2p55))

1s 2s 2p 2p 2p1s 2s 2p 2p 2p



HH

HeHe NeNe

LiLi


1st IE1st IE(kJ/mol)(kJ/mol) BeBe

BB

CC

NN O O

FF

ZZeffeff = 1 to 2 = 1 to 2






Screening and increasing Zeff

2s to 2p2s to 2p



HH

HeHe NeNe

LiLi


1st IE1st IE(kJ/mol)(kJ/mol) BeBe

BB

CC

NN O O

FF

88OO1s 2s 2p 2p 2p1s 2s 2p 2p 2p

n = 1 to 2n = 1 to 2

pairing energypairing energy

increasing n andpairing energy



HH

HeHe

NeNe

ArArKrKr

LiLi NaNa KK RbRb



24002400

18001800

12001200

600600

Trends recur throughout periodic tableTrends recur throughout periodic table



Elem.Elem. Elec. Config.Elec. Config. I I11 I I22 I I33 I I44 I I55 I I66

NaNa [Ne]3s[Ne]3s11 496496 45604560

MgMg [Ne]3s[Ne]3s22 738738 14501450 77307730

AlAl [Ne]3s[Ne]3s223p3p11 577577 18161816 27442744 1160011600

SiSi [Ne]3s[Ne]3s223p3p22 786786 15771577 32283228 43544354 1610016100

PP [Ne]3s[Ne]3s223p3p33 10601060 18901890 29052905 49504950 627062702120021200

SS [Ne]3s[Ne]3s223p3p44 999999 22602260 33753375 45654565 6950695084908490

Core ElectronsCore ElectronsBeing RemovedBeing Removed



Sample exercise: Based on the Sample exercise: Based on the trends discussed in this section, trends discussed in this section, predict which of the following atoms, predict which of the following atoms, B, Al, C, or Si - has the lowest first B, Al, C, or Si - has the lowest first ionization energy.ionization energy.




As atoms get smaller, the ionization energy gets As atoms get smaller, the ionization energy gets larger, so the lowest ionization energy belongs to larger, so the lowest ionization energy belongs to the largest atom.the largest atom.





Size decreases as you go across the period, so Size decreases as you go across the period, so the left-most atom is the largest.the left-most atom is the largest.





Size decreases as you go across the period, so Size decreases as you go across the period, so the left-most atom is the largest.the left-most atom is the largest.

AlAl


Electron Affinities (EA)Electron Affinities (EA)Electron Affinities (EA)Electron Affinities (EA)

Electron Affinity - Electron Affinity - the energy associated with the energy associated with adding an electron to a gaseous atomadding an electron to a gaseous atom..

E(g) + eE(g) + e-1-1 E E--

11(g)(g) Signs;Signs;

– Negative (exothermic) when energy is Negative (exothermic) when energy is released upon adding an electron.released upon adding an electron.

– Positive (endothermic) when energy is Positive (endothermic) when energy is required to add an electron.required to add an electron.

– Most neutral atoms and all ions (cations) Most neutral atoms and all ions (cations) have negative (exothermic) EA’s.have negative (exothermic) EA’s.



200200

100100

00

-100-100

-200-200

-300-300

-400-400

EAEA(kJ/mol)(kJ/mol)


HH

HeHe

LiLi

BeBe

BB

CC

NN

OO

FF

NeNe

NaNa

MgMg

AlAl

SiSi

PP

SS

ClCl

ArAr

KK

CsCs



00EAEA

(kJ/mol)(kJ/mol)


HeHe

LiLi

BeBe

FF

NeNe

NaNa

MgMg

ClCl

ArAr

KK

CsCsFilled Filled Shell Shell

AlreadyAlready

ns to npns to np

npnp55 to to Filled Filled Shell Shell

nsns11 to to

nsns22


Summary of General Observations:Summary of General Observations:– Neutral atoms and cations, EA exothermic (neg).Neutral atoms and cations, EA exothermic (neg).

– EA becomes more negative across period (ZEA becomes more negative across period (Zeffeff increases).increases).

– Group 2 EA positive because of nsGroup 2 EA positive because of ns22 to ns to ns22npnp11 addition.addition.

– Gp 18 has filled shell (no need to gain electrons).Gp 18 has filled shell (no need to gain electrons).– Gp 15 has significant electron-electron Gp 15 has significant electron-electron

repulsions (pairing electrons going from nsrepulsions (pairing electrons going from ns22npnp33 to to nsns22npnp44).).

– EA’s do not range significantly down group EA’s do not range significantly down group (because decreased nuclear attraction (Z(because decreased nuclear attraction (Zeffeff) is ) is offset by decreased electron-electron repulsions).offset by decreased electron-electron repulsions).



Trends and Group Trends and Group PropertiesPropertiesTrends and Group Trends and Group PropertiesProperties

Trends of radius, IE, EA, etc. are useful in Trends of radius, IE, EA, etc. are useful in predicting chemical behaviorpredicting chemical behavior

radius, IE, etc.. are ATOMIC properties radius, IE, etc.. are ATOMIC properties (individual atoms) which only noble gases exist (individual atoms) which only noble gases exist as isolated atoms in nature.as isolated atoms in nature.

Trends and properties of groups of atoms (and Trends and properties of groups of atoms (and atoms in compounds) are also useful (i.e., atoms in compounds) are also useful (i.e., metal, non-metal, conductor, insulator, etc...).metal, non-metal, conductor, insulator, etc...).


Non metal characterNon metal characterincreasesincreases


Metals, Nonmetals and Metals, Nonmetals and MetalloidsMetalloidsMetals, Nonmetals and Metals, Nonmetals and MetalloidsMetalloids

metalsmetals non-metalsnon-metals

GoldGold GraphiteGraphite



metalsmetals non-metalsnon-metalsconductorsconductors insulatorsinsulators

shinyshiny dulldull

high thermal conductivityhigh thermal conductivitythermal insulatorsthermal insulators

solids at RTsolids at RT (except Hg) (except Hg) freq. non-solids at RTfreq. non-solids at RT

ductile and malleableductile and malleable brittlebrittle

Metalloids (along line in table) have properties between metals and non-metals



metalsmetals non-metalsnon-metalsLow Ionization EnergiesLow Ionization Energies High IEHigh IE

tend to form cationstend to form cations tend to form anions tend to form anions

TM’s form multiple + statesTM’s form multiple + states Tend to form single Tend to form single (-) (-) states states

Basic OxidesBasic Oxides Acidic OxidesAcidic Oxides

Metalloids (along line in table) have properties between metals and non-metals


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

1H 2He

3Li 4Be 5B 6C 7N 8O 9F 10Ne

11Na 12Mg 13Al 14Si 15P 16S 17Cl 18Ar

19K 20Ca 21Sc 22Ti 23V 24Cr 25Mn 26Fe 27Co 28Ni 29Cu 30Zn 31Ga 32Ge 33As 34Se 35Br 36Kr

37Rb 38Sr 39Y 40Zr 41Nb 42Mo 43Tc 44Ru 45Rh 46Pd 47Ag 48Cd 49In 50Sn 51Sb 52Te 53I 54Xe

55Cs 56Ba 57La 72Hf 73Ta 74W 75Re 76Os 77Ir 78Pt 79Au 80Hg 81Tl 82Pb 83Bi 84Po 85At 86Rn

87Fr 88Ra 89Ac 104Unq 105Unp 106Unh 107Ns 108Hs 109Mt

58Ce 59Pr 60Nd 61Pm 62Sm 63Eu 64Gd 65Tb 66Dy 67Ho 68Er 69Tm 70Yb 71Lu

90Th 91Pa 92U 93Np 94Pu 95Am 96Cm 97Bk 98Cf 99Es 100Fm 101Md 102No 103Lr

metalsmetals

metalloidsmetalloids

non-metalsnon-metals


Metallic Metallic PropertiesPropertiesIncreaseIncrease

NonmetalliNonmetallic c

PropertiesPropertiesIncreaseIncrease


Compounds of metals and nonmetals tend to be Compounds of metals and nonmetals tend to be ionic.ionic.

Metal Oxides are basic;Metal Oxides are basic; Metal Oxide + WaterMetal Oxide + WaterMetal Hydroxide Metal Hydroxide NaNa22O(s) + HO(s) + H22O(l)O(l)2 NaOH(aq)2 NaOH(aq) KK22O(s) + HO(s) + H22O(l)O(l) 2 2 KOH(aq)KOH(aq) MgO(s) + HMgO(s) + H22O(l)O(l)Mg(OH)Mg(OH)22(aq)(aq) Metal Oxide + AcidMetal Oxide + AcidSalt + WaterSalt + Water MgO(s) + 2 HCl(aq)MgO(s) + 2 HCl(aq)MgClMgCl22(aq) + H(aq) + H22O(l)O(l) FeFe22OO33(s) + 3HNO(s) + 3HNO33(aq)(aq)Fe(NOFe(NO33))33(aq) + 3H(aq) + 3H22O(l)O(l) CuO(s) + HCuO(s) + H22SOSO44(aq)(aq)CuSOCuSO44(aq) + H(aq) + H22O(l)O(l)

Metal Compounds : Metal Metal Compounds : Metal OxidesOxidesMetal Compounds : Metal Metal Compounds : Metal OxidesOxides


Nonmetals reacting with metals give salts Nonmetals reacting with metals give salts (electron receivers)(electron receivers)

Non metal oxides are acidic;Non metal oxides are acidic;Nonmetal oxide + waterNonmetal oxide + water

acidacid PP44OO1010(s) + 6 H(s) + 6 H22O(l)O(l)4 H4 H33POPO44(aq)(aq) BB22OO33(s) + 3 H(s) + 3 H22O(l)O(l)2 H2 H33BOBO33(aq)(aq) SOSO33(g) + H(g) + H22O(l)O(l)HH22SOSO44(aq)(aq) Nonmetal oxide + baseNonmetal oxide + base

salt + watersalt + waterCOCO22(g) + 2NaOH(aq)(g) + 2NaOH(aq)

NaNa22COCO33(aq) + H(aq) + H22O(l) BO(l) B22OO33(s) + 6NaOH(s) + 6NaOH2NaBO2NaBO33(aq) + 6H(aq) + 6H22O(l)O(l)

Non-metal CompoundsNon-metal CompoundsNon-metal CompoundsNon-metal Compounds


COCO22 Nonmetal Chemistry Nonmetal ChemistryCOCO22 Nonmetal Chemistry Nonmetal Chemistry

Carbon dioxide (COCarbon dioxide (CO22) is a “typical” non-metal ) is a “typical” non-metal

and dissolves in water to form an acidic and dissolves in water to form an acidic solution:solution:

COCO22(s) + H(s) + H22O(l)O(l) HH22COCO33(aq)(aq)

HH22COCO33(aq) + H(aq) + H22O(l)O(l) HH33OO++(aq) + (aq) +

HCOHCO33--(aq)(aq) HCOHCO33

--(aq) + H(aq) + H22O(l)O(l) HH33OO++(aq) + (aq) +

COCO33-2-2(aq)(aq)

pH - measure of the acidity of a solution.pH - measure of the acidity of a solution.

Indicators - display different colors depending Indicators - display different colors depending upon the pH of the solution.upon the pH of the solution.

Demonstration 6.2

Nonmetal oxides are acidicNonmetal oxides are acidic


Along Diagonal Line in Periodic TableAlong Diagonal Line in Periodic Table

Have properties between metals and Have properties between metals and nonmetalsnonmetals

Metalloid oxides - AMPHOTERIC -Metalloid oxides - AMPHOTERIC -

–As bases:As bases:AlAl22OO33 + 6H + 6H++ 2Al2Al+3+3 + 3 H + 3 H22OO

–As Acids:As Acids: AlAl22OO33

+ 2OH+ 2OH-- + 3 H + 3 H22OO 2 Al(OH) 2 Al(OH)44--

MetalloidsMetalloidsMetalloidsMetalloids


Group Trends: Group I Group Trends: Group I (1A)(1A)Group Trends: Group I Group Trends: Group I (1A)(1A)

33LiLi77

1111NaNa2323

1919KK3939

3737RbRb8585

5555CsCs133133

8787FrFr223223

Alkali MetalsAlkali Metals

MOST REACTIVEMOST REACTIVE

LiLi NaNa K K



33LiLi77

1111NaNa2323

1919KK3939

3737RbRb8585

5555CsCs133133

8787FrFr223223

Alkali MetalsAlkali Metals

1st IE 1st IE decreasedecrease

ss

Radius Radius increaseincrease

ss

mp/bp mp/bp decreasedecrease

ss

electron electron sharing dec. sharing dec. (covalency)(covalency)




Soft, metallic solids.Soft, metallic solids. Low first ionization energies (electron Low first ionization energies (electron

donors); form +1 ions. Form pure metals donors); form +1 ions. Form pure metals by electrolysis (passing electrical current by electrolysis (passing electrical current through a molten salt).through a molten salt).

2Na2Na++ + 2e + 2e-- 2 Na2 Na 2Cl2Cl--

ClCl22 + 2 e + 2 e--

Reactions dominated by 1 electron loss Reactions dominated by 1 electron loss (to 1+) [i.e., Rx with hydrogen = MH; Rx (to 1+) [i.e., Rx with hydrogen = MH; Rx with S = Mwith S = M22S,etc...].S,etc...].

MH are hydride compounds (HMH are hydride compounds (H-1-1 not H not H++).).

33LiLi77

1111NaNa2323

1919KK3939

3737RbRb8585

5555CsCs133133

8787FrFr223223



Oxides:Oxides:Li + OLi + O22 2Li 2Li22OO lithium lithium

oxide [O]oxide [O]2-2- 2Na + O2Na + O22 Na Na22OO22 sodium peroxide [Osodium peroxide [O22]]2-2-K + OK + O22

KO KO22 pot. superoxide [Opot. superoxide [O22]]--

React with water to form React with water to form hydroxides;hydroxides; 2M + 2 H2M + 2 H22OO

2 MOH(aq) + H2 MOH(aq) + H22

HH22O O reactivity; Li - v. slowly; Na - reactivity; Li - v. slowly; Na - vigorously; K - inflames; Rb & Cs - vigorously; K - inflames; Rb & Cs - explodeexplode

React Flame Tests - elements React Flame Tests - elements excited to higher state by the excited to higher state by the flame and then emit light as they flame and then emit light as they return to the ground state (Na - return to the ground state (Na - yellow, 3p to 3s).yellow, 3p to 3s).

33LiLi77

1111NaNa2323

1919KK3939

3737RbRb8585

5555CsCs133133

8787FrFr223223


Flame TestsFlame TestsFlame TestsFlame Tests


Group Trends: Group 2 Group Trends: Group 2 (2A)(2A)Group Trends: Group 2 Group Trends: Group 2 (2A)(2A)

44BeBe99

1212MgMg2424

2020CaCa4040

3838SrSr8787

5656BaBa137137

8888RaRa226226

Alkaline Earth MetalsAlkaline Earth Metals


MgMg Ca Ca



44BeBe99

1212MgMg2424

2020CaCa4040

3838SrSr8787

5656BaBa137137

8888RaRa226226



ss


ss


ss

electron electron sharing decr. sharing decr. (covalency)(covalency)



Tendency to lose two electrons to form Tendency to lose two electrons to form MM+2 +2 cations (achieves noble gas electron cations (achieves noble gas electron config.).config.).

Mg(s) + ClMg(s) + Cl22(g)(g) MgClMgCl22(s) and (s) and MgCl(s)MgCl(s)

Flame Tests: Ca - brick red; strontium - Flame Tests: Ca - brick red; strontium - crimson red (in fireworks); barium - crimson red (in fireworks); barium - green.green.

In nature;In nature; berylberyl BeBe33AlAl22(SiO(SiO33))66

dolomitedolomite CaCOCaCO33MgCOMgCO33

limestonelimestone CaCOCaCO33


44BeBe99

1212MgMg2424

2020CaCa4040

3838SrSr8787

5656BaBa137137

8888RaRa226226




55BB1111

1313AlAl2727

3131GaGa7070

4949InIn115115

8181TlTl204204


ss


ss


ss

electron electron sharing decr. sharing decr. (covalency)(covalency)+3 Ox. State

+1 Ox. State


Boron Compounds; Boron Compounds;

Numerous Polyhedral Compounds (covalent)Numerous Polyhedral Compounds (covalent)

Boron Neutron Capture TherapyBoron Neutron Capture Therapy Aluminum;Aluminum;

2Al + Fe2Al + Fe22OO33 AlAl22OO33 + 2Fe + 2Fe

THERMITE REACTIONTHERMITE REACTION

Gemstones; AlGemstones; Al22OO33 (Alumina) (Alumina)

trace Crtrace Cr+3 +3 = ruby= ruby

trace Fetrace Fe+2+2, Fe, Fe+3+3, Ti, Ti+3 +3 = blue sapphire= blue sapphire


55BB1111

1313AlAl2727

3131GaGa7070

4949InIn115115

8181TlTl204204


• Dictionary - “A number of things held together”.Dictionary - “A number of things held together”.• Earliest Man-made Polyhedra: Neolithic Scots Earliest Man-made Polyhedra: Neolithic Scots • Plato : Five “Platonic” Bodies: All Triangular Face (Its Plato : Five “Platonic” Bodies: All Triangular Face (Its

not what you discover but who publishes not what you discover but who publishes FirstFirst))• tetrahedrontetrahedron trigonal trigonal octahedronoctahedron dodecahedrondodecahedron icosahedronicosahedron

bipyramidbipyramid

• Archimedes Archimedes : Thirteen Semi-Regular Polyhedra Derived : Thirteen Semi-Regular Polyhedra Derived from the Platonic Solidsfrom the Platonic Solids

Clusters??Clusters??Clusters??Clusters??


Boron Neutron Capture Boron Neutron Capture Therapy (BNCT)Therapy (BNCT)Boron Neutron Capture Boron Neutron Capture Therapy (BNCT)Therapy (BNCT)

thermal neutron

thermal neutron

10B 11B* 7Li + + 2.4 MeV

to Cells CELL



88OO1616

1616SS3232

3434SeSe7979

5252TeTe128128

8484PoPo209209

ChalcogensChalcogens


ss


ss

mp/bp mp/bp increaseincrease

ss



Oxygen - two allotropes Oxygen - two allotropes (allotropes - different form of (allotropes - different form of the same element) - Othe same element) - O22 and O and O33..

Great tendency to gain Great tendency to gain electrons (oxidize other electrons (oxidize other elements)elements)

Most common OMost common O-2-2.. S reacts similarly to oxygenS reacts similarly to oxygen


88OO1616

1616SS3232

3434SeSe7979

5252TeTe128128

8484PoPo209209

ChalcogensChalcogens


99FF1919

1717ClCl3535

3535BrBr8080

5353II127127

8585AtAt210210


ss


ss


ss



HalogensHalogens


Greek for “salt formers”.Greek for “salt formers”. Diatomic in elemental state (FDiatomic in elemental state (F22, Cl, Cl22, Br, Br22, ,

etc...).etc...). Highest electron affinities - form EHighest electron affinities - form E-1-1 anions. anions.

–F removes electrons from almost F removes electrons from almost everything else.everything else.

–Reacts with most metals directly to form Reacts with most metals directly to form salts.salts.

–Reacts with hydrogen to form hydrogen Reacts with hydrogen to form hydrogen halides which dissolve in water to form halides which dissolve in water to form acids (all except HF are strong acids).acids (all except HF are strong acids).

99FF1919

1717ClCl3535

3535BrBr8080

5353II127127

8585AtAt210210



Group Trends: Group I8 Group Trends: Group I8 (8A)(8A)Group Trends: Group I8 Group Trends: Group I8 (8A)(8A)

22HeHe44

1010NeNe2020

1818ArAr4040

3636KrKr8383

5454XeXe131131

8686RnRn222222


ss


ss


ss


Noble GasesNoble Gases


Very unreactive and have closed shell Very unreactive and have closed shell electronic configurations [called noble or electronic configurations [called noble or inert gases].inert gases].

All are monoatomic in native state.All are monoatomic in native state. 1962, Bartlett noticed that Xe has a similar 1962, Bartlett noticed that Xe has a similar

ionization energy to oxygen and could ionization energy to oxygen and could possible form compounds with Xe.possible form compounds with Xe.– Reacted Xe with very strong oxidizer Reacted Xe with very strong oxidizer

(remover of electrons) F and O to form (remover of electrons) F and O to form XeFXeF22, XeF, XeF44, XeF, XeF66, XeO, XeO33, etc..., etc...

– No compounds of He, Ne or Ar are known No compounds of He, Ne or Ar are known and only one compound is known for Kr and only one compound is known for Kr (KrF(KrF22).).

Group Trends: Group I8 Group Trends: Group I8 (8A)(8A)Group Trends: Group I8 Group Trends: Group I8 (8A)(8A)

22HeHe44

1010NeNe2020

1818ArAr4040

3636KrKr8383

5454XeXe131131

8686RnRn222222

Noble GasesNoble Gases

CHE 106 Prof. J. T. Spencer 68Setting up ionic Setting up ionic compounds, molecular compounds, molecular compounds, and chemical compounds, and chemical equationsequations

Setting up ionic Setting up ionic compounds, molecular compounds, molecular compounds, and chemical compounds, and chemical equationsequationsSample exercise: Predict the Sample exercise: Predict the

formula of the compound formula of the compound formed by Rb and Se.formed by Rb and Se.




RbRb1+1+ SeSe2-2-




RbRb1+1+ SeSe2-2-

RbRb22SeSe


Setting up ionic Setting up ionic compounds, molecular compounds, molecular compounds, and chemical compounds, and chemical equationsequationsSample exercise: Write the Sample exercise: Write the

balanced chemical equation balanced chemical equation for the reaction between for the reaction between copper II oxide and sulfuric copper II oxide and sulfuric acid.acid.




CuCu2+2+ O O2-2-




CuCu2+2+ O O2-2-

CuO + HCuO + H22SOSO44




CuCu2+2+ O O2-2-

CuO + HCuO + H22SOSO44 CuSO CuSO44 + H + H22OO


Chapter SevenChapter SevenChapter SevenChapter Seven

Periodic Table Trends and Periodic Table Trends and GeneralizationsGeneralizations

Electron ShellsElectron Shells Atomic Radii and screening (shielding)Atomic Radii and screening (shielding) Ionization EnergyIonization Energy Electron AffinitiesElectron Affinities Metals, Nonmetals and MetalloidsMetals, Nonmetals and Metalloids Group I, 2, 16, 17 and 18 Chemistry - Group I, 2, 16, 17 and 18 Chemistry -

Examples of above concepts and Examples of above concepts and trendstrends

Documents

CHE 106 Prof. J. T. Spencer 1 Chapter Seven: Periodicity v Periodic Table - Organizes many “facts” and trends in chemical reactivity v Based upon electronic