Periodic Properties of Elements in the Periodic Table Chapter 38.

38
Periodic Properties of Elements in the Periodic Table Chapter 38

Transcript of Periodic Properties of Elements in the Periodic Table Chapter 38.

Page 1: Periodic Properties of Elements in the Periodic Table Chapter 38.

Periodic Properties of Elements in the Periodic Table

Chapter 38

Page 2: Periodic Properties of Elements in the Periodic Table Chapter 38.

Periodic Table (Modern Form)

Page 3: Periodic Properties of Elements in the Periodic Table Chapter 38.

Periodic Law The properties of

elements are a periodic function of their atomic number

P = F(z)

Page 4: Periodic Properties of Elements in the Periodic Table Chapter 38.

Periodic Law When elements

are arranged in order of atomic number, similar properties recur periodically.

Li

NaK

Atomic radii vs. Z

Page 5: Periodic Properties of Elements in the Periodic Table Chapter 38.

Periodic Law

Atomic number

First Ion

ization

En

ergy

Page 6: Periodic Properties of Elements in the Periodic Table Chapter 38.

Why Periodic Law?

Chemicaland Physicalproperties

Type ofBondingandstructure

Atomicproperties

Atomic number

Page 7: Periodic Properties of Elements in the Periodic Table Chapter 38.

Ionization Energies

H

HeNe

Ar

Li Na K

N

Be

BC O

F

MgP

AlSi S Cl

Ca

Atomic number

First

I.E.

Variations:1. Across a period2. Down the group

Page 8: Periodic Properties of Elements in the Periodic Table Chapter 38.

Atomic radius

HHe

Li

Na

NeAr

K

Be

Mg

Ca

Page 9: Periodic Properties of Elements in the Periodic Table Chapter 38.

H

37

He

54

Li

156

Be

105

B

91

C

77

N

71

O

60

F

67

Ne

80

Na

186

Mg

160

Al

143

Si

117

P

111

S

104

Cl

99

Ar

96

K

231

Ca

197

Sc

161

Ti

154

V

131

Cr

125

Mn

118

Fe

125

Co

125

Ni

124

Cu

128

Zn

133

Ga

123

Ge

122

As

116

Se

115

Br

114

Kr

99

Rb

243

Sr

215

Y

180

Zr

161

Nb

147

Mo

136

Tc

135

Ru

132

Rh

132

Pd

138

Ag

144

Cd

149

In

151

Sn

140

Sb

145

Te

139

I

138

Xe

109

Cs

265

Ba

210

Hf

154

Ta

143

W

137

Re

138

Os

134

Ir

136

Pt

139

Au

144

Hg

147

Tl

189

Pb

175

Bi

155

Po

167

At

145

Rn

La

187

Ce

183

Pr

182

Nd

181

Pm

181

Sm

180

Eu

199

Gd

179

Tb

176

Dy

175

Ho

174

Er

173

Tm

173

Yb

194

Lu

172

Atomic Radius (pm) 1pm=1x10-12m

Page 10: Periodic Properties of Elements in the Periodic Table Chapter 38.

Electronegativity

H

He Ne Ar

F

Cl

Li Na KCaEl

ectr

oneg

ativ

ity

Atomic number

Page 11: Periodic Properties of Elements in the Periodic Table Chapter 38.

Electronegativity

H2.1

Li1.0

Be1.5

Na0.9

Mg1.2

Al1.0

K0.8

B2.0

C2.5

N3.0

O3.5

F4.0

Al1.5

Si1.8

P2.1

S2.5

Cl3.0

Ne -Ar -

He-

Increase in electronegativity

Decrease

Page 12: Periodic Properties of Elements in the Periodic Table Chapter 38.

Melting Points

m.p./oC

1000

2000

3000

4000

0 5 10 15 20

Atomic number

-1000

0

C

Si

He Ne Ar

Ca

Page 13: Periodic Properties of Elements in the Periodic Table Chapter 38.

Melting Points

H-259

Li180

Be1280

Na97.8

Mg650

Ca850

K63.7

B2300

C3730

N-210

O-218

F-220

Al660

Si1410

P44.2

S119

Cl-101

Ne -249

Ar -189

He-270

Unit: oC

Increase

Page 14: Periodic Properties of Elements in the Periodic Table Chapter 38.

Periodic Variation of Physical Properties Structure & Bonding

Giant metallic Giant covalent Simple molecular

Page 15: Periodic Properties of Elements in the Periodic Table Chapter 38.

Periodic Variation of Chemical Properties

Formulae of hydrides, oxides, chlorides

Hydrolytic behaviours and explanations

Page 16: Periodic Properties of Elements in the Periodic Table Chapter 38.

Peiodicity in formulae

Li Be B C N O F Ne Na Mg Al Si P S Cl Ar

6

4

2

Moles of Cl atoms per mole of atoms of element

Page 17: Periodic Properties of Elements in the Periodic Table Chapter 38.

Hydrides

Period 2 LiH BeH2 B2H6 CH4 NH3 H2O HF

Period 3 NaH MgH2 AlH3 SiH4 PH3 H2S HCl

Ionic Covalentwith someioniccharacter

TypicallyCovalent

Polarcovalent

Page 18: Periodic Properties of Elements in the Periodic Table Chapter 38.

Hydrides

Bonding Hydrolytic behaviour

Ionic NaH + H2O NaOH + H2

(H- + H2O OH- + H2)

Be(OH)2, Mg(OH)2, Al(OH)3 are alkalineH3BO3 is acidic

Covalent withionic character

BeH2 + 2H2O Be(OH)2 + 2H2

MgH2+ 2H2O Mg(OH)2 + H2

B2H6 + 6H2O 2H3BO3 + 6H2

AlH3 + 3H2O Al(OH)3 + 3H2

Page 19: Periodic Properties of Elements in the Periodic Table Chapter 38.

Hydrides

TypicallyCovalent

CH4 does not dissolve nor react

SiH4 reacts to give SiO2.2H2O + H2

PH3 very slight soluble

SiH

H HH

:OH2 SiH

HOH

H

+ H2 etc

Page 20: Periodic Properties of Elements in the Periodic Table Chapter 38.

Hydrides

Polar covalent NH3 + H2O NH4+ + OH-

H2S + H2O H3O+ + HS-

HF + H2O H3O+ + F-

HCl + H2O H3O+ + Cl-

Note: From gp4 to gp7

Acidity increases because polarity of bond increase

Page 21: Periodic Properties of Elements in the Periodic Table Chapter 38.

Check point 38-3

H-O-H :NH3 OH- + NH4++

H2O: + H-Cl H3O+ + Cl-

N is more electronegative, hence more basic than Cl.It reacts with water by donating its lone pair electron.

CH4 , due to its non-polar covalent bond, it does notdissolve nor react with water.

Page 22: Periodic Properties of Elements in the Periodic Table Chapter 38.

Oxides

Ionic

Ionic withCovalent character

Amphoteric Al2O3

Covalent Acidic CO2

SO2

NO2

Basic Na2O

Page 23: Periodic Properties of Elements in the Periodic Table Chapter 38.

Ionic Oxides

O2- + H2O 2OH-

Na2O(s) + H2O(l) 2NaOH(aq)Li2O(s) + H2O(l) 2LiOH(aq)MgO(s) + H2O(l) Mg(OH)2(s)

Page 24: Periodic Properties of Elements in the Periodic Table Chapter 38.

Amphoteric Oxides

Al2O3 + 6H+ 2Al3+ + 3H2OAl2O3 + 2OH- + 3H2O 2[Al(OH)4]-

BeO + 2H+ Be2+ + H2OBeO + 2OH- + H2O [Be(OH)4]2-

Page 25: Periodic Properties of Elements in the Periodic Table Chapter 38.

Covalent Oxides

O=X+ :O-H H [O-X-OH]- + H+

Mechanism of the Hydrolytic behaviourof covalent oxides:

CO2 + H2O H2CO3 H+ + HCO3-

SO2 + H2O H2SO3 H+ + HSO3-

2NO2 + H2O HNO3 + HNO2

Page 26: Periodic Properties of Elements in the Periodic Table Chapter 38.

Covalent Oxides

P4O6 and P4O10 :

P4O6(s) + 6H2O(l), cold 4H3PO3(aq)P4O6(s) + 6H2O(l), hot 3H3PO4(aq) + PH3(g)P4O10(s) + 6H2O(l) 4H3PO4(aq)

The actual reactions are complicated.The products formed depend on the amount of water present and the conditions of reaction.

Page 27: Periodic Properties of Elements in the Periodic Table Chapter 38.

Covalent Oxides

Group VIIA: F2O, Cl2O and Cl2O7

F2O(g) + H2O(l) 2HF(aq) + O2(g)Cl2O(g) + H2O(l) 2HOCl(aq)Cl2O7(l) + H2O(l) 2HClO4(aq)

ClO O

O O

ClO

OO

Cl2O7(g)/(l)

ClO O

O O

ClO

OO

+ -

Cl2O7(s)

Page 28: Periodic Properties of Elements in the Periodic Table Chapter 38.

Check point 38-4

a. SiO2 does not react with water. The giant covalent structure has high lattice energy. It is not possible to break it down in aqueous solution.

Page 29: Periodic Properties of Elements in the Periodic Table Chapter 38.

Chlorides

LiCl

NaCl MgCl2

Ionic

AlCl3

BeCl2

Intermediatewith covalentcharacter

BCl3 CCl4

SiCl4

NCl3

PCl5PCl3

OCl2

S2Cl2SCl2

ClF

Cl2

Covalent

Page 30: Periodic Properties of Elements in the Periodic Table Chapter 38.

Ionic chlorides Group IA

LiCl, NaCl are not hydrolysed in aqueous solution, neutral solution formed when dissolved. NaCl (s) Na+(aq) + Cl-(aq), LiCl (s) Li+(aq) + Cl-(aq)

Group IIA MgCl2 is not hydrolysed. Hydrated crystals undergoes hydrolysis when h

eated. MgCl2.6H2O MgCl(OH) + 5H2O + HCl

Page 31: Periodic Properties of Elements in the Periodic Table Chapter 38.

Intermediate chloridesBeCl2 and AlCl3 :

Be2+ and Al3+

High charge/size ratio, strong polarizing power,cation hydrolysis.

Be2+ :OH

H:OH2

Be(OH)2 + HClBeCl2 + 2H2O

AlCl3 + 3H2O Al(OH)3 + 3HCl

Page 32: Periodic Properties of Elements in the Periodic Table Chapter 38.

Covalent chlorides

Group IIIA BCl3 Cl

ClClB+

:OH2

Due to presence of vacant orbital and the polarB-Cl bond.

BCl3 reacts vigorously with water to giveboric acid, H3BO3 and HCl.

BCl3(l) + 3H2O(l) H3BO3 (aq) + 3HCl(aq)

Page 33: Periodic Properties of Elements in the Periodic Table Chapter 38.

Covalent chloridesGroup 4A : CCl4 and SiCl4

Cl

Cl ClClSi

Cl

Cl ClClC

CCl4 does not hydrolyzed by water

SiCl4 hydrolyzes.SiCl4(g) + 4H2O(l) SiO2.2H2O(s) + 4HCl(aq)

Page 34: Periodic Properties of Elements in the Periodic Table Chapter 38.

Covalent chlorides

Group VA: NCl3

NCl3(l) + 3H2O(l) NH3(aq) + 3HOCl(aq) chloric(I) acid

N does not have low-lying vacant orbital,it hydrolyses through the donation of lone pairelectron of N atom to the H atom of water molecule.

:OH

H:N-Cl3

Page 35: Periodic Properties of Elements in the Periodic Table Chapter 38.

Covalent chlorides

Group VA: PCl3 and PCl5

PCl3(l) + 3H2O(l) H3PO3(aq) + 3HCl(aq)PCl5(s) + 4H2O(l) H3PO4(aq) + 5HCl(aq)

P is less electronegative than Cl.PCl3 and PCl5 hydrolyze by accepting the electron pair from water molecule.

Page 36: Periodic Properties of Elements in the Periodic Table Chapter 38.

Covalent chlorides

Group VI: SCl2 , S2Cl2

SCl2(g) + H2O(l) HSCl(aq) + HOCl(aq)S2Cl2(l) + 2H2O(l) H2S(g) + SO2(g) + 2HCl(aq)

Group VII: FCl, Cl2

FCl(g) + H2O(l) HF(aq) + HOCl(aq)Cl2(g) + H2O(l) HCl(aq) + HOCl(aq)

Page 37: Periodic Properties of Elements in the Periodic Table Chapter 38.

Check point 38-5

Give the equation for the reaction between the following compounds with water:

a. AlCl3b. Cl2O6

Page 38: Periodic Properties of Elements in the Periodic Table Chapter 38.

Past paper questions

Periodicity

1999 IIA 3c2001 IIA 3c