Adobe Scan 24 Mar 2024
Adobe Scan 24 Mar 2024
Adobe Scan 24 Mar 2024
1
SYLLABUS
·pJic properti-es and variations of properties - Physical a,id Clien . I
fef1 · ·odic properties and thei r variarions in groups a ., . · uc"
il pen . . . · nu pcnods.
( ,Ii •,;ons and trends r,_f the .followm g periodic . . .
Oe1 m1 . f)lop eri ws ,n K' m . 0 .d .
• atomic.'r1 ze . • m<'fal/i c clra racter ~p~i " p eri od~ should be .Hudied;
·oni w twn p ote11flt1I
• I -
elec rrorz r.1- .
• no,1 -mctall, c cha racter
O u l/11 () '
eriodicil y on 1he bas is of ato mi c number for elcn~e11ts.· • ,,[ectrrml' gati vity
(ii ) P
• The study of mod<'m. periodic
,. tablr up to period ., ( . _
.
questions ,nil 1'(' n s"-ed 0 11 <!lem ents bevond .., .·sruden11·
J ·
to he
. exposec1to the complete m odern periodic table but
110 • · I · pe u o 4 - Calc wm )·
• f eriodic1 ry .and ot 1cr rela ted
. properties
. to be t,xp 1m.ned on tl, r. b .·· .r
'special ref erenCf' to the a lka li metal,· alkal · · ci.H s 01 n.uc 1.ear charge and shells (not orbitals)·
( . ,, m e ea rt1l· metal
, . i1a IOf?ens and i n ert g a ses)
s, '
, 4ccordin~ ro 1he recommendatw 11 of fntemar,· U .
1 nwn of P ·
,,Vote· ,11m1bered
' ' fro m I to l 8 rep lacinf{ rh ·
e older notataria
· ·• . ure anc.I A p p 1·ie d Chemistry (I UPAC), the groups a re
• • L · wn 01 groups I A VI/A VJ
r.raminaiion borh nora11011s will be a ccepted. ...... , II. IB ... ... . V//B and 0. Howeve r, for the
38 0: 39 41 0 42 □ 43 44 45 tTl C:
· 37 0 0 40 D □ D □ 46 □ 47 □ 48 □· 49 □ 50 □
y Mo Tc Ru Rh Pd Te- t -, . :,::, 3
Rb Sr Zr Nb Ag Cd ln Sn fr Sb' - ::I
Zircomum Niobium Mulyhdenum Technetium Ruthenium Rhodium Palladi um Silver Cadmium Indium l;eUl!rium , Q v,
SIJ'Ontium Ynnum Tm j( Anrimm)/ o-
_i:.i
I -
1
F9 Ne 10
F
BS c6 N7 08
T
I 3 to 10 Ll 3 Be 4 2,8
2. Short 8 2 ,3 2,4 2 ,5 2.6 2.7
I 2 ,1 2,2
- -
[ 4 5 6 7 8 19110 11 12 Al 13 Si I4 p 15 s ,6 c1I1 Ar 18
3
3. Short 8 18 I Na,, I Mg ., VIII 18 118 2 .8 ,3 2 .8 .4 2,8 ,5 2 .8,6 2 .8 ,7 2,8, 8
r --
J 2, 8,2 : 2,a, ~
111B IVB VB VIB VI IB
Br35 KrJ6
4. Long
I
I 18 j 19 to 36 1 K 19 I Ca 20 T 1l AN SITION ELEfv' EN s
I I __ ~ 8. 112. ~ - -- --· 1
s3 Xes4
5. Long 18 ~ to 54 1 Rb 37 _ _ !___
- - - -- - Alas Rns6
Acsg
7. Longest I 87~ o .. Fr 87 LLI 71
KLMNOP
--
£ \el11ents
tbC 2nd r
~to,niC ]'
The th.inf period clements. Na. Mg. Al , Si. F (9) 2 2, 7 S f,tect ron
, ecr,nd configu t
P. S and Cl. s ummari se the prope rtie s of their C l ( I 7J ]
2, 8. 7 l'hird
respecti,·e group.o- and a re called typical elements. Ur (J.'i) 4 2. 8. 18, 7 F ['lo- of s
0Urth
A period is detennined by rhe number of shells and a I (53 ) 5 2, 8, 18, 18. 7 Fifth ygleDC)
---
in the ou1ennost shell. }lydri<
For example : Sodium ha~ ato mi c number 11 a nd its .'1cross a period, i.e., from left tori h
(h)
. f I f .
/ electronic confi gu ration is 2. 8. I . It has three orbits On moving rom e t to nght ·m a givengt.. In tl
1
(shells) and has one e lec tron in the o utermost orbit, the number of shell s re main s the sarn l'en I •
I hence it is placed in third pe riod a nd group l. Similarly. I
example , in the 2nd period, the number ;- F
calcium. atomic number 20. electroni c configuration 2, 0
8. 8. 2 is placed in fo urth peri od a nd group 2.
remains two, i. e., equal to the number of the s.
Similarly in the third period the number of~
1.3 PERIO DICITY remains three and so on .
The properties that reappear at regular intervals, (2) Valency
or in w hich there is gradual variation (i.e.
increase or decrease) at regular interval s, are Valency denotes the combinjng capacity of
called periodic propenies ' and the phenomenon atom of an element. It is equal to the number
is .known as the periodicity of elements. electrons an atom can donate or accept or shaJt
I
Note 1 : Valency depends on the number
1.4 SHELLS (ORBITS) AND VALENCY electrons in the outermost shell (i.e. vale
shell). If the number of electrons present in
/ Orbits : Electrons revol ve around the ~ ucleus in
I certain definite circular paths called orbits or
shells.
outermost shell are 1, 2, 3 or 4, then their valency
is I, 2, 3 or 4 respectively.
I
\
--- If the number of electrons present in the
( 1) Number of she1ls : outermost shell are 5, 6 or 7, then their valency
fa) Down a group, i.e., from top to bottom. is 8 - 5 = 3, 8 - 6 =2 and 8 - 7 = 1 respectively,
Note 2 : Valency is the combining capacity so it
The number of shells increases successively,
z. e., one by one, such that the number of shelJs that is always positive.
OJ
-- -: -
Gro11P-"
IA
I
IlA
2
IIlA
13
JVA
14
VA
15
VIA
16
VII.A
17
Zero
18
5.
~ame two elements in each case .·
(1) Alkali metals ..
(~11)) Alkaline earth metals
L-- ;; -
f fe,neJI •od Li Be B C N 0 F Ne 6
(iii) Halogens rv Inert gas
. Elements of group 1 and elements of group 17 both
11te 2Pd pen
4 5 6 7 8
have valency 1. Explain.
9 10
~
'.l
7 . Correct the statements. .
KL KL K L KL K L KL
~ KL K L
(i) Elem ents in the sam e p~r·i~ t 'h
tJecfroPIC 2, I 2. 2 2, 3 2.4 2,5 2, 6 2. 7 2, 8
valency. _ _ ave the same
j configll111tioll
(ii) Valency depends upon the b f '; . , : ' l)f\~ t)
,
s.
ce of on the basis of their similar propertie
of electron s are see n afte r a diff eren s ?
bers. (i) · What are those similar propertie
2, 8, 8. 18. 18 and 32 in atom ic num group or family ?
electrons (ii) What is the common name of this
• Properties of elem ent s dep end upon of the last element in
it) so 12 . What is the main characteristic
in the vale nce she ll (o ute rmo st orb each period of the Periodic Tabl
e ? What is the
n with
grad ual cha nge in pro per ties is see general name of such elements ?
I increase in ato mic num ber. 13. According to atomic structure, what
determines which
1 a nd 2 . be the last in a
• Re acti ve me t a ls are in gro up element will be the first and which will
w
. yV;>(\ , N~'..
~
?
'·)
£,,......
tl
1
riod, from left to right or down the group from ~ ~oto ~ in the nucJeus~ e. :__ the atomic nu At
p to bottom, are called Periodic Propertie
s.
A1
An increase in nucl ear charge decreases -
Important periodic properties are : ~ El
size of the atom because the electrons are C<
(i) atomic size (atomic radius), attracted towa rds the nucl eus with a greater
fooi
(ii) metallic character, thereby bringing the oute nno st shell closer to
1M
nucleus.
(iii) non-metallic character, s
(iv) ionisation potential (ionisation energy), Trends in ato mic size (atomic radius)
( v) electron affinity,
la) Down a ,:!ro op:
(vi) electronegativity.
In u grou p. rhe increases 111
.\ i :_e of' an ato111
1.5. I Atomic size (atomic radius) oiu• f>roc ad r 1'wn tr,p to b~r! om. This is due to ~
successive addition of shells (which overweighs ~ ti,
It i., the di:rra,u-c hetw em thc centrc ol the .
mc~eased nuclear charge) as one moves frorn
nucl eus ff m, atmn and its ouremw.\t .\heft.
Penod to the next in a group. For example:
l I]
· Groun 1 In group 17 the size of fluorine is the 11
E/efflents"' r F < Cl < B sma est.
In group 1 the size of hydrogen is the smallest. 64 r < I < At
99 114 133 140
Electronic pm pm pm pm
cs AtolJUC Atomic Size pm
~ No. radius configuration
(b) Across a period :
-
KLMNOP
In a pe riod, the si::.e of an atom dec reme . ft·
feFt t . I Thi . . s om
Hydrogen J 37 pm I 0 thJ' t ng· 1.
0 1 s 1s because the nuclear char
b . .
ge, i.e.,
e a orruc. num er mcreases from left to right m · the
L---
same pen 00 , thereby bringing the outermost shell
Lithium 3 152 pm 2. l
0 ~loser to the nucleus. Therefore, in the second period,
it ha~ ~en fo~nd that lithium (Li) has the largest
-- atonuc size while fluorine (F) has the smallest.
sodium JI 186 pm 2, 8, l
~ I~ the third period, sodium atom is the largest in
size and chlorine atom is the smallest.
Na > Mg > Al > Si > P > S > Cl
~
Potassium 19 231 pm 2. 8, 8, 1 186 pm 160 pm 143 pm 117 pm 110 pm 104 pm 99 pm
•
period. This is because the outer most shell of inert
Rubidium 37 244 pm 2, 8, 18, 8, I
gases is complete. They have the maximum number
of electrons in their outermost orbit thus the
electronic repulsions are maximum. The effect of
'S nuclear pull over the valence electrons is not
•
I/
262 pm 2, 8, 18, 18, 8, I seen. Hence, the size of the atom of an inert gas is
Caesium 55
bigger, but not bigger than the alkali metal of
the same period.
I Elements
Atomic No.
Lithium
3
Beryllium
4
--- --
Boron
5
-
Carbon
6
Nitrogen
7
Oxygen
8
Fluorine
9
Neon
10
Electronic KL KL KL KL
KL KL KL
configuration KL 2,4 2, 5 2,6 2, 7 2,8
2, 2 2, 3
2, l
Size
(@ (®) @ @ @ @) @) @
Note : 1. Cation is always smaller than the parent atom, from which it is formed .
Reason
· ··
· f 1 t · so elec tro ns are
· a cauon.
(s) hence proton(s) are more than electron(s) m
Cat1on 1s fonned by the loss o e ec ron ' h • d
strongly attracted by the nucleus and are pulled inward. Hence t e size ecreases.
Na-e- ~ Na+
(2, 8, I ) (2, 8)
Thus sodium ion is smaller than sodium atom.
[D
. e . Gr ea ter the
ato mi c Si~
st orb
• ter mo it, an d thu s, Ies
. A
At omh icis the ou
SlZ
- ,/i)
, ert ed on 1t. s .a res n
t.he parent ato m.ele ctro n(s), fart er cle Mp u 11 ex Ac ro ss a
Anion is lar ger tha n ain of
nu be rem ov ed mo re heasily fr o
by the (f) a rc mo re tha
n is the n(s ) can . On rn
;· on : Ani on is fonned thu s ma km g t e elerne
ens . num be r o f e lec rro n - ·11 rhe nuc leu s
thectr
ele val
·h
o e nce s e , 11 11 inc rea ses cl
rhe
Thu s,( t)l1eThc effectiv e pos iti ve cha rg: ;d - H e nce thu s the '
-d II is ex pcn e n re me tal lic .
proron s - _
is less, so less rnw ar pu . Gr ea ter the nu cle ar char can no t los
size exp and s,
Cl+ e- ~ Cl
-
mo
(ii) Nu clea~15 ~';,~;~:;ce ex ert ed by the nucleu s g,,
os t orb it. l'h~
There:
(2. S. 7) -
(2. 8) s.
th . t:·l1lo rine atom .
gre
th e electron
ater
. ·rt-
( ) of the
s
, It to rem
.
o ute
o ve the
.
rm I
ron (s) •q
e ect11· fro11
lg a pe
,
rio
Ex
d,
,a;
- - - b gge r an 1 - r1 s havi ng rhe. ma kes ,t d , icu
-
Thu s chl onnc ron i s I. . ns ,_e. c1e Io • th e o ute r.mo s t o rbi t.
T hu s m eta 1c nature mo st met
romc d '° ids UfJO II rhe nuc lea , Li
3. Size of isoelect f rons. cpe · r h · e
e,u · c rug decreases. L---
same nu mb er o elect ) Grea.ter 1..s lh"'~ 11ud Me t
" rge (no. of proton s . let e their
cha
. h lose ele ctr on (s)M to coJ mp
(nu clea r pul l) sma ller is the
size . Ele me nts wh IC
re d uc1•ng ag en ts . eta s are g 00d
Eramp le : oc te t are
ency to lose
Isoelec rronic ions Mg-'+ Na + F- 0 2-
red ucr.ng age , rits · Gr ea te r the te. nd In tl
10 10 10 (s) , str on ge r is the red uc ing ag ent. ele me nt
/ No . of electrons
1() electron
12 11 9 8
I No . of protons 1.5 . 3
ac te r
Size in A ~ 0-65 0-95 1-26 1-42 Trends in me ta llic ch ar Th
Down a group ele ct rm
1_5_2 Metallic ch ara cte r , the ato mi c o rbit. <
·f! a ten den cv to los e On mo vin g do wn a gr ou p
Those c/£'111e111s. ll'hiclt hm cle ar ch arg e als o Li i: N1
ctro ns of the ou ten no st size inc reases an d the nu
(1)
Na - e- ~ Na+
K C:
de nc y to los e in va lenc
(2. 8. 1) (2, 8) nu clear ch arg e. Th ere for e, ten Rb 3"
me nts ca n los e 0
F
Mg - 2e- Moe,2+ ele ctr on inc rea ses an d ele Cs
inCl
me tal lic na tu re
c,,
~
1 an d
ele ctr on s ea si ly . Th us
ll)
c,,
(2, 8, 2) (2, 8)
wn a gr ou p.
increases as on e mo ves do
nt (non me tal) which does a gro up are most
Note : Hy drogen is an eleme Elements at the bo tto m of
y one electron and one ns
lar ge , he nc e electro
noc have a neu tron , it has onl
it forms its cation which metallic. Th e atornic siz e is
proton. On los ing this ele ctron for me d. Th us,
also be are loosel y held, so ion s are rea dil y
has onl y one pro ton , therefore its cation can rea cti ve .
called a proton . the se ele me nts are mo re (i)
the least
H- e- ~ H+ Ex am ple : In group 1, lit hiu m is (i;
metallic ele me nt.
The metallic character of ele
ments dep en ds on:
is a rad ioa cti ve ele me nt, so
(i) atomic size and (ii) nuclear charge. No te : Fra nc i um
t -"nown.
its properties are no
- 12
(ii
- - -ble
. Ta
'P- - . - - --- -,. . -
G;:
fr. ro::-:u:::p-- -"7 ""- .: O~U:-
'R~
G:-
GROUP14 - ~ U P1. 5
. ---- -- -, -- --- --7
-R_O_U_'P_2~ -GROUP 13
J--+- G J8~ -
_P__
Ar
r-: ;:~~ -- -t --- - - _ GR~ S 16 / GROU _R
7 t--G
ClP_ J_ _U
_O
-- ir .- AJ
- -- -
- - S;- - _ P__
TrE
mea tm=unb :-1-- +- --
er "t- --1
Na Mg
18- - -
fll!Je
G au
\.:to::: ·:c=-= -::-- 17-- -t -- --
16 -- .- --
- -- - - ,- - -~ - - -
14 _ - .- r- -- De
-
- ni;c- -- +--K.,- L12M .,_ _K_ LI 3M
- L-, M
- t - -K, K_L_ M_ _
t;; ec~tro
El;:_--
2 -- L_ M_- +- _
- -t---K
- K --.-L-,M
~- ~- M K. L. M
2, s: 2 2 • s· 3
- _!:Urafioo
/C(>lJIIJj , s. 1 4 2 8 5 of
8·,_:7_- -t_
~:- ~ :._2:~ 8,'. .8:_ -
~ r-;_~=•-.::-·,~,,,-;- --f ~2-._8_,_6_ +- _2
""1ic
MebtlJ y
Me w
--3
Meial
--t--4--1- -
--:;----~--~J~
I ~=
~=-1~=~
~e i; ,
:~ '
Meial!'_
o;d No n-m
1
Non-metal Noble gas
nt;
e--n:cyc--=-L~1.--;--1-1- t_:_2_-t
P"" " No n-metal at1
o -
a1~
1--/rv:~ J__ 3_ _ ~ =- 4 3 2 1
_
si
ft
[! J i -- -- -- -L _ _ -- 1 ._ _ -L_
sO per iod Exa mp le : Group 14
.
AcfOS rno vin g acr oss a per iod , . nuc lea r pul l Non -me tal
on due to the mcr . eas e .m ato1TI1c num ber and C
, Si Me tall oid
·ncrease s rea ses . Hen ce, ele me nts
1 tb atom ic size dec "] Ge Me tall oid
thUS e
caJJIIOl Jose electrons eas 1. y. Sn Me tal
Therefore, the m eta 11ic_11at u~c
d«•crt·a .\·es aer o., ,.
Pb Me tal
. d. 111011i11g fro m l<:ft to n!!,hl.
a per10 , righ t)
Exa mp le : In the 2nd period
, lith ium is the Ac ros s th~ per iod (lef t to
, the ten den cy to
rnost metallic . . On mo vin g acr oss a per iod
to an inc rea se in
B L_~ _o F gam ele ctro n(s ) inc rea ses due
~
J
in the ato mic size .
Metals
Met allo id Non -me tals nuc lea r pul l and a dec rea se
tf'r i11 1·u, a.\e s nrT oss
The refo re, 111 11-111!'f(f/lic rl1111'11c
1
.
or/iii. 1,rc t'Onsidc•·~·d , ·s non -me tals No te : Non -metals arc oxi dis
in g agent'-. .
7 electrons in
Non-metals usuali y have 5, 6 or 1-··--
periodicity.
n 3, 2 or 1 electron The nature of oxides also shows
their outermost orbits. They can gai 1
of ele me nh in a
or to complete their Acr oss a per iod : The oxi des
respectively, in order to attain octet bas ic natu re and
form an anion. partir-ular per iod sho w dec rea sing
valence shells (outermost orbits) and mple, the oxides of
For example. chlorine (Cl) and
oxygen (0) gain fi nall y bec ome acid ic . For exa
to form anions. elem ents of the third period.
1 and 2 electron(s) res pec tive ly P2 O 5 SO 3 CJ 2O 7
~ c1- Al2O 3 SiO 2
Cl + e- Na2O MgO
(2, 8, 8) Basic Amphoteric Feebly Acid
ic More Mos t
(2, 8, 7) Strongly
acidic acidic
acidic
0 + 2e- 0 2- basic
re of oxid es of met als
(2, 6) (2, 8) Dow n a gro up : The ha sic natu
ends on : increases.
Non-metallic cha rac ter also dep
(i) atomic size and (ii) nuc lea r charge.
atomic size, greater
Ch em ica l reactivity
(i) Atomic size : Smaller the s upon their
den cy to gain The reactivity of elements depend
is the nuc lea r pul l and the ten s to complete their
nt is more tendency to lose or gain electron
ele ctro ns. Th ere for e, the ele me ten den cy to lose
out erm ost orbit. Gre ate r the
non-metallic by nature. electron(s), greater is the reactiv
ity in the case of
the nuclear charge,
(ii) Nucl.ear charge : Greater me tals . Sim ilar ly gre ate r the
tendency to gain
tron(s), hence
greater is the tendency to gain elec electron(s), greater is the reactivity
of non-metals .
more non-metallic is the element.
r Trends in ch em ical reactivity
Trends in non -m eta llic ch ara cte
Across a period :
Down a group itio n On moving from left to tight in a per
iod, the
ses due to the add
The atomic siz e inc rea t decreases and
siv e per iod s. Tho ugh t~e che mical reactivity of elements firs
of new shells ove r suc ces
to an inc rea se ~n then increa ses.
nuclear cha rge inc rea ses , due trons easily
the eff ect of an inc rea sin g atorruc The group l element can lose elec
atomic num ber group 2 elements
'r. Th ere for e, no n -m eta lft · 11 ' mr e as compared to group 2. Similarly,
size is gre ate
decreases down the gro up. · 9- I
L---
----,-- - - T - r - - - - -, . _
r-- - , I I ! --
I in comparison ' Element of . M , Al Si ! ~
can also Jose electrons easily but on ~
I
to group 1. 3rd period I Na ___l _ g_l_ _!_ - J_ p
I
i
o _-97
o-_5_4 __,___ 0 -86 1-53
' - -~
1-87 I
\\ 11 . :~:::
1 (i) So
depends upon the tendency to lose electrons, thu s
\ (iii) M:
reactivity increases on going down the group. __,.'" lntext QuestionsJ
I 12. Whicl
(i)- B
State Its \
gro ur 1. What do you understand by atomic size ?
13. The
2. Give the trends in atomic size on moving : Ca,
The chemical reactivity of non-metals decreases
(i) down the group, (i) \
on going down the group as it depends upon the
(ii) across the period left to right.
tendency to gain electrons, which decreases down
(ii)
the group. 1 ,-. r.· 2:, :::..1-:t1·,;e .,t., dTK(~ 3. Arrange the elements of second and third periOd .
increasing order of their atomic size (excluding n
0:
top group ~ ~ :.e.. f· Jorme . gases). 14 . W r
co
G aaarion in :,,ivs1car ~rool!i> ,e!l 4. Why is the size of (i) neon greater than fluorine? (Ii) s \ thr
is greater than magnesium ? \
The melting and boiling points of metal s
15. N
j
5. (i) Which is greater in size ?
ecrease on going down the group, e.g., (i)
(a) an atom or a cation
~ Is m.p. b.p. I ~ (b) an atom or an anion
\ (ii
I Li 180-5°C 1347°C I ~ (c) Fe2+ or Fe3+ I
\ (ii
Na 94-5°C 883 °C I ~ (ii) Which has higher E.A., Fluorine or Neon.
K 63-5°C 774°C -o (iii) Which has maximum metallic character Na, Li or K
(i'
- ---- 6. Arrange :
• The melting and boiling points of non-metals
mcrease on going down the group.
(i) Be , Li, C , B , N , 0 , F (in inc reasing metallic
character) .
\\
Non- -- (ii) s
i, Na, Al , Mg, Cl , P, S (in decreasing non-metallic 16.
/ Metals m.p. b.p. Physical character) .
..___ --- state
I Fluorine - 219-6°C - I 87oc gas
7.
~tate the trend in chemical reacti vity :
Chlorine -101 oc -34-6oC . ht
(1) across the third period left t0 rig
gas ( 11.. ) ,
1
Bromine -7•2°C down the group.
+58-8°C liquid \
Iodine +I 13-6°C a. in group IA ( 1) b. in group VII A (17) I
+183 °C solid 8.
A metal M forms . \
10
.
18. Explain why are the folio wing
(iii) name the family to which it belongs. .) AII groups contain met I statem ents not correct:
d when x (I
(iv) write the formula of the compound forme ..) A as and no
toms of elements in th e same ng metals .
( II
reacts with ~~Y. roup have the
er , ... same number of electron(s).
o. n,e given t~bl~ shows elements with same numb (111) Non-metallic chara cter decre
1 ases across a period
of electrons In its valence shell. with increase in atom·,c numb er
(iii) a total of three shell s with five elect rons in its electrons, atomic numbers).
valence shell ? 21 . Give reasons for the following :
in its size of a
(iv) a total of four shell s with two elect rons (i) The size of a c1- ion is greater than the
valence shell ? I
Cl atom .
(v) twice as many elect rons in its secon
d shell as in (ii) Argon atom is bigger than chlorine atom.
I
1
H eh um wt ll ha ve the highest io . (E . A .) is t
' ,\ ,.
! . Note : • ( ha lo ge ns ) a
rnof - l w hi le caes·I IJtl) r
,, 1·, 11 lli
nd s on · , en er gy 23 72 -0 kJ
Ionisation energy depe the . nr. sa tio n e , Ui
nuclear charge . . . e ' / w ill ha ve th e
l ow es t 10
(i) atomic size (ii) the atorm c siz of Fr is not dete ne r~
. . •- ·. The greater . . the electronh
s 37 5· 0 kJ moJ -. 1 (Id.E. . . ). lA
( 1) At om ic sr;:,erce 10act1ve
I ( I)
Sm ee
co rre ct ly as it 1s ra
•
ctw n.
Jesser the fo of attra
further away ~rom _t e
H
ha ve lo w I.E.
I
m ost shell lie
of the ou ter . e. , M et al s u s ua lly -7 3
eir removal easrer, l gh I.E .
nucleus. thus make th no n- m et al s ha ve hi 11 Li
required is less . . -- -- - - - -
the ionisation energy
- 60
I -
e nu cl ea r
ge : The gr ea t~ r th ff in it y (E . A .)
(ii ) Nu cl ea r ch ar ns 1.5.5 E lfl cf ro n A Ill Na
raction for the electro --~,,in rn tr.a lp y
charge. greater is the att
- 53
ns
. Therefore, the electro
of th ; outermost sheU
We ha ve ju st studie
d th at to remove an e
are more firmly he ld
in the outermost shell to gy is re qu ire d. Si llli
lar!y
ter energy is required fro m an at om , en er
because of which grea is ad de d to an atom
, en '
(s) . an ex tra el ec tro n
. ··e - - remove the electron
- - - ---
~ .g v re le as ed . m or e th;
L, -. ·1 - -c - t
- - - ed while conv
---- -- gy re le as causin g
C Across a period
I • '( I
The am ou nt of
ra l ga se ou s
en er
is ol at ed at om in to
a negati
• I I'
ne ut addition
·, l ,j
ar ge d ga se ou s io n (a ni on ) by the lower
ch .)
cause the atomic size
decreases ec tro n Affinity (E.A
(with exceptions), be electron is ca lle d El lower
thus,
nuclear charge, an d
X (g) + e- ➔ X- (g
an in cr ea se in the ) + E.A. fl uori
due to on(s).
is qu ire d to remove the electr there
n in its gaseous state.
m ore en er gy re
X is any element take in cor.
The elements vo lts pe r at om (e
V/atom)
of the 2nd Li Be B C N 0 F Ne , U ni t : el ec tron esented by ne • E.
period l. El ectron af fin ity is repr
--
Ionisation
/I kJ. mo/
I
[ -
sign - ] e.g.,
al
e:
Cl(g) + e- ➔ CI-(g) +
energy in 80 1 1086 1402 13 J
4 168 J 2080 349 KJ/mol . iI
520 899
--
1
kJ moJ-1 I
ity of chlorine is - 349 Kl 11
I Therefore, electron affin
The elements
1
off.be 3rd Na Mg AJ Si S
p I
Cl Ar , '1 :
/ J>eriod
I (i) clear charge. Th
atomic size and (ii) nu
I
1496 737
I
t
111 ; •• i · . 2-2
Na - 53 I G I 0-7 0-9 1-8 1-9 1-9 2-0
more than the nuclear charge, thereby K - 48 I .J, N C R E A s N G ➔
rtlIJg, --L~ - -
!nf'rI gt L\ l \ h(lt'l' ,-, /'(I l'l1 c f l /Ill u!Jt ll// \' ,,, /' " \ { /{ \ 't ' ,·u/1u \, Down a group
du ,· to th, ·11 , 1,1h/ 1 • -lcc!rt!l! i, c u11/11;ur1t111 11 rl1 n 1 /i11d 1r There is an increase in atomic number down a
,rons ..
di/j1rn/1 to llfffJ)l dee group, i.e. , nuclear charge increases, but due to the
• Gro up\ 2 and 15 do not shew,; regul ar trend~ in d ec tro11 addition of extra shells, the atomic size increases. The
affin ity \':tl ue~. The) are exc eptions.
comes the
effect of an increase in the atomic size over Not e:
nucl ear char ge, henc e
effec t of an increase in the • Grea ter the vaJue of elec tron affinity , easj
', /JP"rf~, i1ecrc, ., .•· af'w n , i:ro11r. lle er
is to gain elect ron( s~ and more non,l Diag onal •
ntly .
For example, in the first group, it sign ifica or mor e e lectr oneg ative or.
more oxicti
s1110I)
incre asing t,
ium . .d.1smg tre nd in thf
decr ease s from lithium dow nwa rds to franc the elem ent. Th us ox1 pow er in
.od and decr easesere seco nd peri
ln t"• '- \ 11 f• l tl If H' ' ,, 'h' (1
left to righ t in a pen top elem ents of
botto m in a grou p.
at right dia!
• Met als lose eJec tron s. The y have rela tion st
II I •I
ioni satio n ener gy (ion jsati on potential) I
le elem ents a
. · l l '
eJec tron a ff m1ty, ess e ectro nega tivit
, , I ,, 'ti 1
Gro up -
I' I/(,, ( I I .. II
have larg e atom ic radi i as com pare d ti Perio d 2
,'/
·, , •11 ..
\ \, /I
1 ',' I
, ', '!Ill\ .
I, •'Ii<'/ ('('{/'(
fill\ /.\
'.'I<
1/ (C ft
<'(,'/{\ '/
meta ls. Met als are goo d reducing agents.
--- Period 3
~
(b) n
Non-metallic character Increases ➔ • Atomic radii - Decreases • Ionis ation potential 3. State
Ionisation potentiaJ Increases ➔ • Atomic radii - Decr eases • Nucl ear charg e (a)
Electron affinity Increases ➔ • Atom ic radii - Decreases • Nucl ear charg e (b )
Electronegati vi ty Increases ➔ • Atomic radii Decr eases . Nucl ear charg e 4. Narr
ene
PRO PER TIE S - Dow n a Group (a)
• VARIATION (TRENDS) IN PER IOD IC
5.
- .--- - -
G R O U P- Atomic Ionisation / Elect ron Elect ro- Meta llic
__0A ) _3SIIA )...:_ ~1MI A) Size PotentiaJ Affinity I negativity I Vale nce
Elec trons
(b)
Characterl
2. Li Smallest
-- - High e; t-· - t - High~ ~ 1
Be 4 F9
Hpst
I
I4.
JI JI
6. (a]
Ca20
jf iil
1f
K,9 Br3s ~
j
V,
I5. (I)
l
V,
Rb37 Sr38 Is3 Largest Lowe st Lowe st (b
Low est High est
I
L.-
PERTIES D
• REASONS FOR TRENDS IN PERIODIC PRO - own a Group 7. E
I_ TRENDS (Variation) - p
REA SON
• Atomic size tc
Increases J, • No of shell s Incre ases 8.
• Meta llic chara cter Increases -L _
• Atomic radii Incre ases
• Ionisation potemiaJ Decreases
• Non- meta llic chara cter Decr eases J, • Atomic radii _
Incre ases Decreases
• Ionis ation poten tial Decr eases -L • Ionisation potentiaJ
• Atomic radii _
Incre ases
• Elec tron affin ity Decr eases J, • Atomic radii _ ~ic num ber increases down ~
Increases ou_p but nucl ear charge _effect ~:
Dec~e~se~ J,_ l _•_ ~lom ic radii
• EJec trone gat_iv_i_tY_ __ _ mina ted by an increase m atonu
Increases
----·-----------_- ----- - ·- ---==--
dii or incre ase in number of shells,
GJ
- · - -•· -latio~ship
- : Properties which have (c) The most electronegative element from the following
Oiagona re .
- trend in a group, generally have decreasing element is :
increasing .
•n the period. That ,s why the elements of the (i) Magnesium (ii) Chlorine
trend d1 period show · • · h th
resemblance m properties wit e (iii) Aluminium
secon h. d .00 (iv) Sulphur. (2019)
1 eJemen
ts of the next group of the t. 1r pen , .present 9. Explain the following :
• ht diagonal of the element. Thi s leads to a diagonal
1 atng . (a) Group 17 elements are strong non-metals, while
I relationship, viz. Li & Mg , Be & Al , B & S1. These
1
(b) The element with highest ionisation potential is : symbols of the elements.
A. Hydrogen B. Caesium 3 4 5 6 7 8 9 10
(b) Among the elemen_ts given below, the element with 12. A group of elements in the Periodic Table are given ~lo~
least Electronegativity is : (boron is the first member of the group and Thalhum is
15
e electronic config~r
k at t h h
A close I.ooents rev eals that t ose ele
. hter elem number of protons
.
.
Gallium, Indium,
Thallium
abOV8 of I ,g . an even 4H 12c •
I Boron, Aluminium, .
Answer the following questions
group of elements : .
in relation to the
t metallie character ?
whic h have . umbers like 2 e, 6 .' etc.,
· ' atomic
exam:p ie n
umbers
thei r mass nd 40 Ar.
twice the atomic
I
9Be an 18
(a) Which element has Ihde b:O:xpected to have the
1 woul except 4 • h e an odd number of Pro
(b) Which elemen . I ? /uch av
Elements w,9 23 Na, etc., have their
hinh.coSf e1ee1ronegat1v ty I minium is 2, 8, 1 (A
tionofau
7 . I IB 9 F, 11 = 2Z-+-
~·- 11 s ' the a tomic
like 3 Lt, twice .
numbers+
\
It the electronic configure in the outer she
(c) trons are there numbers I H
3, how many elec
except 141 N and 1 ·
I of thallium ?• . Write the chem,·cal protons and
fbOron,s5. • Arrangcmc, 01 of electrons, h I
(d) The atomic number o ed when bOron reacts 'fabk
. I.➔. : r elements
' • f ·om atom k num er
t
to 20
formula of the compo und form Valence
IH·utrons o Atomic No. (Z) Mass No. (A) No. electrons
with chlorine. the right of this No. of protons or Prou,ns +
. the group to Elements
(e) Will the elements ,n ire or less metallic in Symbol (or electrons) neutrons (A -
bOron group be more meta ,
character ? Justify your answer. Hydrogen H l-
• Conduction and
He 2 4 2
Helium \ Natur•
Atom ic number (Z) I , Li 3 7 4
Lithium
. ,f,111c11 r is equal ro r ll Be 4 9 5
The ar,1111ic 1111111/Jn <~I an c < • umber is Beryllium I
. 1 , ,uc/('1 1 ~ Atomic n
n11111bcr ' ,(proro11s in r u i l . . t because no two Boron B 5 11 6 IMelting point arl
the unique property of an e e~en ' Carbon C 6 12 6 i boiling point
elements have the same atomic number. Nitrogen N 7 14 7
\ Atomic size
. nurn ber (Z) - Number of protons.
• Atom1c Oxygen 0 8 16 8
\
= Number of electrons. Fluorine F 9 19 10 ---- - ~-
\ Ionisation ene
__
Neon Ne 10 20 10
• It distinguishes an element from other element_s,
Sodium Na 11 23 12
because oo two elements have the same atorruc
number. Magnesium Mg 12 24 12
\E,octron am,
Aluminium Al 13 27 14
• It gives the electronic configuration of an e_Iement,
Silico n Si 14 28 14 \ Electronega1
e.g., an element with atomic number 13 will have I
Phosphorus p 15 31
electronic configuration 2, 8, 3. 16
Sulphur s 16 32 16 \ Roactiv\ty
• It helps us in finding the position of an element in Chlorine Cl 17 35, 37 18, 20
the periodic table.
Argon Ar 18 40 22 Reaction ~
For example, the element with atomic number 17 Potassi um K 19 39 20 water and
will ha ve electronic configuration 2, 8, 7. This Calcium Ca 20 40 20
element will be placed in the Jrd period of Group
17 i.e. , VIIA, because it has: (i) three energy shells
and (ii) seven electrons in its outermost shell. Note : (i) Elements with nip (neutron/proton) ratio oxidising
Mass number (A) around 1 are stable, e.g ., light metals like sodium,
Compow
potassium, calcium, etc.
The mass number uf an clement is the sum of fonnatio1
rhe number of pro!om and !ll!Ulrons in the 11uckus (ii) Elements with nip ratio 1-5 and above are
of the atom of that element. radioactive, i.e., they emit radiations. They are unstable
elements, e.g., heavy metals like uranium.
L_
Mass number (A)= No. of protons (p)
+ No. of neutrons (n)
GJ
,~ ~
~,·,
~
,---
Alkali metals [Group 1)
---
/J,
- Elements
()ccur rence
Occur in a combined state due to their reactive
nature.
Occur in a combined state as salts due to their reactive
nature .
I~ I 1-- Shiny white solid metals. Non-metals (coloured); diatomic in the gaseous state.
Physical state
~I They are shiny when freshly cut but soon Fluorine (very reactive poisonous yellow gas)
j become dull as they react with air. Chlorine (poisonous yellow green gas)
Soft, and can be cut with a knife. Bromine (poisonous red brown volatile liquid)
~,
<ij ~
Lithjum is the hardest.
Possess one valenc e electron and therefore
Iodine (dark grey crystalline solid).
Possess seven valence electrons each and therefore
VaJence show simjlar properties.
( electrons
show simj)ar properties.
They form negative ion carrying a single charge
~
They fonn positive ion carrying a single charge
\ eg. Na+ e.g. c1-
\
4
Good conductors of electricity. Non-conductors of electricity.
\
Conduction and
7 Highly reactive, electropositive metals. Highly reactive, electronegative non-metals.
Nature Non-metallic character decreases from
9 Metallic chara cter increases from
lithium (Li) to francium (Fr). fluorine (F) to iodine (I).
11
Decre ases down the group. Increases down the group .
12 Melting point and
/4 boiling point
.
. They have the smallest atomjc size in their period
They have the larges t atomjc size in their period
) I-
16 Atomic size
group . Atomjc size increa ses down the group .
8 The atomjc size further increa ses down the
9
10 They have high I.E. (lower than noble gases) in
0 Ionisation energy They have lowest I.E. in their period .
10 their period .
3 It decre ases down the group .
11 They have high E.A. values . They too decrease
Electron affinity They have low E.A. values which further
down the group (exce ption : Cl has more E.A. than
F).
11
decre ase down the group .
14 I They have high E.N. highest in their period.
Electrooegativity They have the lowest E.N. in their period .
14 E.N. decreases down the group.
E.N. decre ases down the group.
ses
16 They are reactive non-metals. The reactivity decrea
Reactivity They are reacti ve metals. Reactivity
16 down the group.
furthe r incre ases down the group .
7 18, 7fJ
Generally they do not react with dil. acids and water.
They react vigor ously with water and acids
JJ
Reaction with
0 water and acids libera ting hydro gen.
React ivity furthe r increa ses down the group.
0 to
Strong oxidising agents as they accept electrons
Stron g reduc ing agent s as they lose complete their octet.
Reducing/
electr ons to comp lete their octet.
roton)rano oxidising agents Form electrovalent compounds with metals.
Form electr ovale nt comp ound s
:e sodium Compound e.g., KCl, CaC1 2.
with non-m etals. Exam ple : NaCl, KBr. Form covalent compounds with hydrogen and
formation
other non-metals, e.g., HBr, HCI, Hl,CCl4 .
bOve are
a I
e 11nsf3],e