CHAPTER 1PERIODIC CLASSIFICATION OF ELEMENTS&

PERIODICITY

•Basic framework to study the periodic behaviour of physical and chemical properties of elements as well as their compounds.  

Reading the Periodic Table: Classification• Nonmetals, Metals, Metalloids, Noble gases

No. Peculiarity Sub -groups present

No. of elements

s - block elements

p – block elements

d – block elements

f – block elements

1 Shortest A 2 2 0 0 0

2 Short A 8 2 6 0 0

3 Short A 8 2 6 0 0

4 Long A & B 18 2 6 10 0

5 Long A & B 18 2 6 10 0

6 Longest A & B 32 2 6 10 14

7 Incomplete A & B 2 6 10 14

FAMILIES

Name Contents

Alkali metals Group – I A

Alkaline earth metals Group – IIA

Chalcogens Group – VI A

Halogens Group VII A

Noble gases / Inert gases Group VIII A

Coinage metals Group I B

Rare earth elements f – block elements

Actinides fourteen elements that follow actinium (89Ac)

Lanthanidesfourteen elements that follow lanthanum

(57La)

Outer transition metals d – block elements

Inner transition metals f – block elements

BLOCKSThere are four blocks on basis of the valence orbital of the element involved in chemical bonding.

Block Contents

s IA , IIA and He

p IIIA to VIIIA (except He)

d Transition elements

f Actinides & Lanthanides

METALS, NON – METALS & METALLOIDS Properties Metals Non – metals Metalloids

Chemical tendency Lose electrons Gain electrons Can lose or gain electrons

Ionic tendency Form cations Form anions Can form both

Nature of oxides Basic Acidic Amphoteric

Oxide – water interaction

Base is formed Acid is formed Both can be formed

Heat conductivity Good Poor Dual

Electrical conductivity

Good Poor Dual

Examples Most of elements B, O, N, F, CL, I, Br, P, Se, &, H

Si, Ge, As, Sb, Te, , & At

1IA

18VIIIA

12

IIA13

IIIA14

IVA15VA

16VIA

17VIIA

2

33

IIIB4

IVB5

VB6

VIB7

VIIB8 9

VIIIB10 11

IB12IIB

4

5

6

7

Important members - the Elements

• Individual members of selected Elements & their characteristics

H He

Li

Na

K Ca

Mg

Fe

I

Cl

F

P SSi

ONC

Al

ZnCu

Ag

Br

13

• All Group II metals (except Be) react with H2O to form

metal hydroxides and H2 gas (Mg reacts with hot water).

e.g.Ca(s) + 2H2O(l) Ca(OH)2(aq) + H2(g)

Sr(s) + 2H2O(l) Sr(OH)2(aq) + H2(g)

• Be does not react with H2O

Characteristic Properties of the s-Block Elements (SB p.43)

14

• Form normal oxides only, except Sr, Ba which can form peroxides. • All are basic (except BeO which is amphoteric), why?

41.2 Characteristic Properties of the s-Block Elements (SB p.46, notes p. 14)

Group II Elements

2Be(s) + O2(g) 2BeO(s)

2Mg(s) + O2(g) 2MgO(s)

2Ca(s) + O2(g) 2CaO(s)

Ba(s) + O2(g) 2BaO2(s)

2BaO(s) + O2(g) 2BaO2(s)

15

Group II element

Normal oxide

Peroxide Superoxide

BeMgCaSrBa

BeOMgOCaOSrOBaO

———SrO2

BaO2

—————

Be, Mg, Ca peroxide do not exist, why?

Reason: High charge density high polarizing power serious distortion on electron cloud of the peroxide ion

40.1 Characteristic Properties of the s-Block Elements (SB p.43)