Assignment periodic table JH sir 3575 kho tài liệu bách khoa

Topic Page No.Periodic Table & Periodicity Modern Periodic law and present form of the periodic table, s, p, d and f block elements, periodic trends in properties of elements atomic and

Topic Page No.

Periodic Table & Periodicity

Modern Periodic law and present form of the periodic table, s, p, d and f block elements, periodic trends in properties of elements atomic and ionic radii, ionization enthalpy, electron gain enthalpy, valence, oxidation states and chemical reactivity.

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PERIODIC TABLE & PERIODICITY

DOBEREINER TRIAD RULE [1817]

He made groups of three elements having similar chemical properties called TRIAD

NEWLAND OCTAVE RULE [1865]

He arranged the elements in the increasing order of their atomic mass and observe that properties of every

8th element was similar to the 1st one like in the case of musical vowels notation

8

Sa765432

NeDhaPaMaGaRe

1

Sa

LOTHER MEYER ’ S CURVE [1869]

He plotted a curve between atomic wt and atomic volume of different elements

The following observation can be made from the curve

-(a) Most electropositive elements i.e alkali metals (Li, Na, K, Rb, Cs etc.) occupy the peak positions on thecurve

(b) Less electropositive i.e alkaline earth metal (Be, Mg, Ca, Sr, Ba) occupy the descending position of thecurve

(c) Metalloids (B, Se, As, Te, At etc.) and transition metals occupy bottom part of the curve

MENDELEEV ’ S PERIODIC TABLE [1869]

Mendeleev ’ s Periodic ’ s Law

According to him the physical and chemical properties of the elements are the periodic functions of their

atomic masses

This table was divided into nine vertical columns called groups and seven horizontal rows called periods.The groups were numbered as I, II, III, IV, V, VI, VII, VIII and Zero group

MODERN PERIODIC TABLE (MODIFIED MENDELEEV PERIODIC TABLE)

(i) It was proposed by Moseley.

(ii) Modern periodic table is based on atomic number

(iii) Moseley did an experiment in which he bombarded high speed electron on different metal surfaces and

obtained X-rays

He found out that  Z where  = frequency of X-rays

(iv) Modern Periodic Law - The physical & chemical propeties of elements are a periodic function of the atomic

nubmer

LONG FORM/PRESENT FORM OF MODERN PERIODIC TABLE

It consist of 7 horizontal periods and 18 vertical columns (groups)

IA, IIIA, IIIB, IVB, VB, VIB, VIIB,

10 9 8

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

S – Block Elements

1

IA

18 VIII A 1

IV A 15

V A 16

VI A 17 VII A

2 He 4.002 3

6 C 12.011

7 N 14.006

8 O 15.999

9 F 18.998

10 Ne 20.179 11

IV B 5

V B 6

VI B 7 VII B 8 VIII 9 VIII 10 VIII 11

I B 12

II B

13 Al 26.981

14 Si 28.085

15 P 30.973

16 S 32.006

17 Cl 35.452

18 Ar 39.948 19

22 Ti 47.88

23 V 50.9415

24 Cr 51.996

25 Mn 54.938

26 Fe 55.84

27 Co 55.933

28 Ni 58.693

29 Cu 63.546

30 Zn 65.39

31 Ga 69.723

32 Ge 72.61

33 As 74.921

34 Se 78.96

35 Br 79.904

36 Kr 83.80 37

40 Zr 91.224

41 Nb 92.906

42 Mo 95.94

43 Tc 98

44 Ru 101.07

45 Rh 102.905

46 Pd 106.42

47 Ag 107.868

48 Cd 112.411

49 In 114.82

50 Sn 118.710

51 Sb 121.757

52 Te 127.60

53 I 126.904

54 Xe 132.29 55

138.905

72 Hf 178.49

73 Ta 180.947

74 W 183.85

75 Re 186.207

76 Os 190.2

77 Ir 192.22

78 Pt 195.08

79 Au 196.666

80 Hg 200.59

81 Tl 204.383

82 Pb 207.2

83 Bi 207.980

84 Po 209

85 At 210

86 Rn 222 87

227

104

Rf 261.11

105 Ha 262.114

106 Sg 263.118

107 Bh 262.12

108 Hs 265

109 Mt 266

110 Uun 269

114 Uuq

58 Ce 140.115

59 Pr 140.907

60 Nd 144.24

61 Pm 145

62 Sm 150.36

63 Eu 151.965

64 Gd 157.25

65 Tb 158.925

66 Dy 162.50

67 Ho 164.930

68 Er 167.26

69 Tm 168.934

70 Yb 173.04

71 Lu 174.967 90

Th 232.038

91 Pa 231

92 U 238.028

93 Np 237

94 Pu 244

95 Am 243

96 Cm 247

97 Bk 247

98 Cf 251

99 Es 252

100 Fm 257

101 Md 258

102 No 259

103 Lr 260

Classification of the Elements :

s-block elements : When shells upto (n – 1) are completely filled and the last electron enters the s-orbital of the

outermost (nth) shell, the elements of this class are called s-block elements

p-block elements : When shells upto (n – 1) are completely filled and differentiating electron enters the

p-orbital of the nth orbit, elements of this class are called p-block elements

d-Block elements : When outermost (nth) and penultimate shells (n – 1)th shells are incompletely filled anddifferentiating electron enters the (n – 1) d orbitals (i.e., d-orbital of penultimate shell) then elements of this classare called d-block elements

(1) Ist transition series i.e 3d series contains 10 elements and starts from 21Sc –30Zn Filling of electronstakes place in 3d sub-shell

(2) IInd transition series i.e 4d series contains 10 elements and starts from 39Y – 48Cd Filling of electronstakes place in 4d sub-shell

(3) IIIrd transition series i.e 5d series contains 10 elements and starts from 57La, 72Hf – 80Hg Filling ofelectrons takes place in 5d sub-shell

(4) IVth transition series i.e 6d series contains 10 elements and starts from 89Ac, 104Rf –112Uub Filling ofelectrons takes place in 6d sub-shell (incomplete series)

f-Block elements : When n, (n – 1) and (n – 2) shells are incompletely filled and last electron enters into orbital of antepenultimate i.e., (n – 2)th shell, elements of this class are called f-block elements Generalelectronic configuration is (n – 2) f1-14 (n – 1) d0-1 ns2

f-The elements of f-blocks have been classified into two series

1. st inner transition or 4 f-series, contains 14 elements 58Ce to 71Lu Filling of electrons takes place in

4f subshell

2. IInd inner transition or 5 f-series, contains 14 elements 90Th to 103Lr Filling of electrons takes place

in 5f subshell

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PERIODIC PROPERTIES :

VALENCY : It is defined as the combining capacity of the elements The word valency is derived from an

Italian word “Valentia” which menas combining capacity

(b) In period - Density first increases till maximum and then decreases (s-block to d-block increases,

d-block to p-block decreases)

(c) In group - From top to bottom in a group density increases regularly

e.g In VIIA gp - F and Cl are gases (Low density)

Br is liquid (density 3.19 gm/cm– 3)

I is solid (density 4.94 gm/cm– 3)

number of shells containing electrons Due to the presence of these intervening electrons, the valenceelectrons are unable to experience the attractive pull of the actual number of protons in the nucleus Theseintervening electrons act as shield between the valence electrons and protons in the nucleus Thus, thepresence of intervening (shielding) electrons reduces the electrostatic attraction between the protons in thenucleus and the valence electrons because intervening electrons repel the valence electrons The concept ofeffective nuclear charge helps in understanding the effects of shielding on periodic properties

The effective nuclear charge (Zeff) is the charge actually felt by the valence electron Zeff is given by

Zeff = Z –, (where Z is the actual nuclear charge (atomic number of the element) and  is the shielding(screening) constant) The value of  i.e shielding effect can be determined using the Slater’s rules

Atomic radius :

Covalent radius : It is one-half of the distance between the centres of two nuclei (of like atoms) bonded by

a single covalent bond as shown in figure

(a) For homodiatomic molecules dA

Vander Waal ’ s radius (Collision radius) : It is one-half of the internuclear distance between two adjacent

atoms in two nearest neighbouring molecules of the substance in solid state as shown in figure

Vander Waal’s radius does not apply to metal and its magnitude depends upon the packing of theatoms when the element is in the solid state

Metallic radius (Crystal radius) : It is one-half of the distance between the nuclei of two adjacent metal

atoms in the metallic crystal lattice as shown in figure

Thus, the covalent, vander Wall’s and metallic radius magnitude wise follows the order,

rcovalent < rcrystal < rvander Walls

IONISATION POTENTIAL OR IONISATION ENERGY OR IONISATION ENTHALPY :

(i) Minimum energy required to remove most loosly held outer most shell e– in ground state from an isolated

gaseous atom is known as Ionisation Potential

(a) For an atom M, successive ionisation energies are as follows

-M + E1 M+ + e– E1 = IP1

M+ + E2 M+2 + e– E2 = IP2

M+2 + E3 M+3 + e– E3 = IP3

IP3 > IP2 > IP1(b) e– can not be removed from solid state of an atom, it has to convert in gaseous form, Energy required forconversion from solid state to gaseous state is called Sublimation energy

(c) IP is always an endothermic process (H = +ve)

In a period : In a period atomic size decreases and zeff increases so removal of electron become difficult

and IE increases

.increasesIE

increaseszeff

,decreasessize

atomic

NeFONCBBeLi

ELECTRON AFFINITY / ELECTRON GAIN ENTHALPY

The amount of energy released or absored when electron is added to the valence shell of an isolated gaseousatom

X + e– X– + E.A

known as Electron affinity

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Mostly energy is released in the process of first E.A

Zero

Ar

NeClS

FOP

NSiAl

CBMg

BeNa

Due to small size of fluorine, electron density around the nucleus increses The incoming electron

suffers more repulsion In case of chlorine electron density decreases due to large size, decreasing order ofelectron affinity of halogen Cl > F > Br > I

S > O > P > N

Si > C > P > N

N & P have low electron affinity due to stable half filled configuration

Difference between EN and EA

– Tendency of an atom in a molecule – Energy released when an electron is added to

to attract the bonded electrons neutral isolated gaseous atom

– Relative value of an atom – Absolute value of an atom

– It regularly changed in a period – It does not changes regularly

or group

– It has no unit – It is measured in eV/atom or KJ mol– 1

or K.cal mole– 1

ELECTRONEGATIVITY (EN)

(i) The tendency of an atom to attract shared electrons towards itself is called electronegativity

(ii) EN and EA both have tendency to attract electrons but electron affinity is for isolated atoms Where as

electronegativity is for bonded atoms

(iii) A polar covalent or ionic bond of A – B may be broken

as (a) A – B AA– : + B+ (EN A > EN B)

or (b) A – B AA+ + :B– (EN A < EN B)

depending on their tendency to attract bonded electron

(iv) There is no unit of electronegativity as EN is tendency of a bonded atom not an energy

H2.1

8 2

PART - I : OBJECTIVE QUESTIONS

* Marked Questions are having more than one correct option.

Section (A) : Atomic and Ionic Radius

A-1. The correct order of atomic size of C, N, P, S follows the order

A-4. The screening effect of delectrons is

-(A) Equal to the p-electrons (B) Much more than p-electrons

(C) Same as f-electrons (D) Less than p-electrons

A-5. In which of the following compounds manganese shows maximum radius

-(A) MnO2 (B) KMnO4 (C) MnO (D) K3[Mn(CN)6]

A-6. Arrange in the increasing order of atomic radii of the following elements O, C, F, Cl, Br

-(A) F < O < C < Cl < Br (B) F < C < O < Cl < Br

(C) F < Cl < Br < O < C (D) C < O < F < Cl < Br

A-7. The correct order of size would be

-(A) Ni < Pd ~ Pt (B) Pd < Pt < Ni (C) Pt > Ni > Pd (D) Pd > Pt > Ni

A-8. Which group of atoms have nearly same atomic radius

-(A) Na, K, Rb, Cs (B) Li, Be, B, C (C) Fe, Co, Ni (D) F, Cl, Br, I

A-9. In the ions P3 –, S2 – and Cl– the increasing order of size is

-(A) Cl– < S2 – < P3 – (B) P3 – < S2 – < Cl– (C) S2 – < Cl– < P3 – (D) S2 – < P3 – < Cl–

A-10. Atomic radii of Fluorine and Neon in Angstrom units are given by

-(A) 0.72, 1.60 (B) 1.60, 1.60 (C) 0.72, 0.72 (D) None of these

A-11. Which of the following has largest radius

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A-13. Arrange the following in order of increasing atomic radii Na, Si, Al, Ar

-(A) Na < Si < Al < Ar (B) Si < Al < Na < Ar

(C) Ar < Al < Si < Na (D) Na < Al < Si < Ar

A-14. Consider the isoelectronic series :

K+, S2 –, Cl– and Ca2+, the radii of the ions decrease as

-(A) Ca2+ > K+ > Cl– > S2 – (B) Cl– > S2 – > K+ > Ca2+

(C) S2 – > Cl– > K+ > Ca2+ (D) K+ > Ca2+ > S2 – > Cl–

A-15. Which of the following is not isoelectronic

series-(A) Cl–, P3 –, Ar (B) N3 –, Ne, Mg+2 (C) B+3, He, Li+ (D) N3 –, S2 –, Cl–

A-16. In the isoelectronic species the ionic radii (Å) of N3–, Ne and Al+3 are respectively given by

A-19. Element Hg has two oxidation staters Hg+1 & Hg+2, the right order of radii of these ions

(A) Hg+1 > Hg+2 (B) Hg+2 > Hg+1 (C) Hg+1 = Hg+2 (D) None of these

A-20. The correct order of increasing atomic size of element N,F, Si & P

(A) N < F < Si < P (B) F > N < P < Si (C) F < N < P < Si (D) F < N < Si < P

A-21. The correct order of atomic / ionic size

(A) N < Li < B (B) Cl < Mg < Ca (C) Ca+2 < S–2 < Cl¯ (D) Na+ < Mg+2 < Cl¯

Section (B) : Ionization Energy or Potential

B-1. Correct orders of Ist I.P are

-(i) Li < B < Be < C

(ii) O < N < F

(iii) Be < N < Ne

(A) (i), (ii) (B) (ii), (iii) (C) (i), (iii) (D) (i), (ii), (iii)

B-2. The maximum tendency to form unipositive ion is for the elment with the electronic

B-4. A sudden large jump between the values of 2nd and 3rd IP of an element would be associated with

the electronic

configuration-(A) 1s2, 2s2 2p6, 3s1 (B) 1s2, 2s2 2p6, 3s2 3p5

(C) 1s2, 2s2 2p6, 3s2 3p2 (D) 1s2, 2s2 2p6 3s2

B-5. The ionization energy of sodium is 495 kJ mol–1 How much energy is needed to convert atoms persent

in 2.3 mg of sodium into sodium ions

-(A) 4.95 J (B) 49.5 J (C) 495 J (D) 0.495 J

B-6. Ionisation energy increases in the order

-(A) Be < B < C < N (B) B < Be < C < N (C) C < N < Be < B (D) N < C < Be < B

B-7. IP1 and IP2 of Mg are 178 and 348 K.cal mol The enthalpy required for the reqction

Mg  Mg2+ + 2e– is

-(A) + 170 K.cal (B) + 526 K.cal (C) – 170 K.cal (D) – 526 K.cal

B-8. Highest ionisation potential in a period is shown by

-(A) Alkali metals (B) Noble gases (C) Halogens (D) Representative elements

B-9. In which of the following electronic configuration ionisation energy will be maximum

(A) [Ne] 3s2 3p1 (B) [Ne] 3s2 3p2 (C) [Ne] 3s2 3p3 (D) [Ar] 3d10 4s2 4p3

B-10. The ionization energy will be maximum for the process

(A) Ba  Ba++ (B) Be Be++ (C) Cs  Cs+ (D) Li  Li+

B-11. The correct order of second I.P

(A) Na < Mg > Al < Si (B) Na > Mg < Al > Si (C) Na > Mg > Al < Si (D) Na > Mg > Al > Si

B-12. Amongst the following, the incorrect statement is

(A) IE1 (Al) < IE1 (Mg) (B) IE1 (Na) < IE1(Mg) (C) IE2 (Mg) > IE2 (Na) (D) IE3 (Mg) > IE3 (Al)

Section (C) : Electron affinity or Electron Gain Enthalpy

C-1. In which case the energy released is minimum

-(A) Cl  Cl– (B) P  P– (C) N  N– (D) C  C–

C-2. In the formation of a chloride ion, from an isolated gaseous chlorine atom, 3.8 eV energy is released,

which would be equal to

-(A) Electron affinity of Cl– (B) Ionisation potential of Cl

(C) Electronegativity of Cl (D) Ionisation potential of Cl–

C-3. The correct order of electron affinity is

-(A) Be < B < C < N (B) Be < N < B < C (C) N < Be < C < B (D) N < C < B < Be

C-4. Electron addition would be easier in

C-5. In the process Cl(g) + e– HCl–(g), H is

-(A) Positive (B) Negative (C) Zero (D) None

C-6. O(g) + 2e–  O2( g) Heg = 744.7 KJ/mole The positive value of Heg is due to

-(A) Energy is released to add to 1 e– to O–1 (B) Energy is required to add to 1 e– to O–1

(C) Energy is needed to add on 1 e– to O (D) None of the above is correct

C-7. Which of the following process energy is liberated

-(A) Cl  Cl+ + e– (B) HCl  H+ + Cl– (C) Cl + e– Cl– (D) O– + e–  O–2

C-8. Second electron affinity of an element is

-(A) Always exothermic (B) Endothermic for few elements

(C) Exothermic for few elements (D) Always endothermic

C-9. The element having very high ionization enthalpy but zero electron gain enthalpy

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C-13. The electron affinity of the members of oxygen family of the periodic table, follows the sequence

C-16. Which of the following statement is not true?

(A) F atom can hold additional electron more tightly than Cl atom

(B) Cl atom can hold additional electron more tightly than F atom

(C) The incoming electron encounters greater repulsion for F atom than for Cl atom

(D) It is easier to remove an electron from F¯ than Cl¯

C-17. Increasing order of Electron affinity for following configuration

D-3. Bond distance C–F in (CF4) & Si–F in (SiF4) are respective 1.33Å & 1.54 Å C–Si bond is 1.87 Å Calculation

the covalent radius of F atom ignoring the electronegativity differences

D-4. Two elements A & B are such that B E of A–A, B–B & A–B are respectively 81 Kcal / mole,

64 Kcal / mole, 76 Kcal / mole & if electronegativity of B is 2.4 then the electronegativity of 'A' may beapproximately

D-5. The lowest electronegativity of the element from the following atomic number is

D-6. Which one is not correct order of electronegativity

(A) F > Cl > Br > I (B) Si > Al > Mg > Na (C) Cl > S > P > Si (D) None of these

D-7. Calculate the bond length of C–X bond if C – C bond length is 1.54 Å and X–X bond length is 1.2 Å and

electronegativities of C and X are 2.0 and 3.0 respectively

D-10. Which one of the following is incorrect ?

(A) An element which has high electronegativity always has high electron gain enthalpy

(B) Electron gain enthalpy is the property of an isolated atom

(C) Electronegativity is the property of a bonded atom

(D) Both electronegativity and electron gain enthalpy are usually directly related to nuclear charge andinversely related to atomic size

PART - II : MISCELLANEOUS QUESTIONS

Comprehensions Type

Comprehension # 1

Read the following passage carefully and answer the questions.

The minimum amount of energy required to remove the most loosely bound electron from an isolatedatom in the gaseous state is known as ionisation energy or first ionisation energy or ionisationenthalpy (IE1) of the element The energy required to remove the second electron from the monvalentcation is called second ionisation enthalpy (IE2) Similarly, we have third, fourth ionistion enthalpies.The values of ionisation energy depends on a number of factors such as (i) size of the atom (ii)screening effect (iii) nuclear charge (iv) half filled and fully filled orbitals

In a group, the ionisation energy decreases from top to bottom In a period, the value of ionisationenergy increases from left to right with breaks where atoms have somewhat stable configurations

1. Compared to the second ionisation energy (IE2) of an atom, the third ionisation energy (IE3) is

-(A) The same (B) Greater (C) Smaller (D) Half

2. In a period, the ionisation energy is lowest for the

-(A) Noble gases (B) Halogens

(C) Alkaline earth metals (D) Alkali metals

3. The electronic configurations of some neutral elements are given below

Pauling gave method to calculate univalent ion radii by assuming that

(i) In ionic crystal (let M+X¯ ) cations and anions are is contact of each other and sum of their radii is equal to

interionic distance, i.e

¯) X

— M (

d  =   

X

M r r

(ii) The radius of an ion having noble gas configuration is inversely proportional to the effective nuclear charge

felt at the periphery of the ion, i.e.r(M) =

) M ( eff

Z C

Here C is constant of proportionality whose value depends on electronic configuration of ion Thus,

¯)

X M (

d



 =

) M ( eff

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5. The value of constant C for NaF crystals is [given that interionic distance of NaF = 231 pm] :

(A) 231 (B) 115.5 (C) 614.5 (D) 307.25

6. The value of univalent radii for F¯ as calculated by Pauling method is (given that interionic distance of

NaF = 231 pm) :

(A) 94.5 pm (B) 136.5 pm (C) 111.68 pm (D) 115.5 pm

7. The value of ‘C’ for Na+, Mg2+ and Al3+ will be in the order :

(A) Al3+ > Mg2+ > Na+ (B) Al3+ < Mg2+ < Na+ (C) Al3+ = Mg2+ = Na+ (D) Can’t be compared

Comprehension # 3

The amount of energy required to remove, an electron from the last orbit of an isolated (free) atom ingaseous state is known as ionisation energy or first ionisation energy of the element Similarly the energyrequired for the removal of the electron from the unipositive ion (M+ produced above) is referred to assecond ionization energy and thus the third, fourth etc

The ionisation energy depends on various factors like nuclear charge, size of atom, type of configurations,screening effect and penetration power of the electrons

8. Which of the following statement is correct ?

(A) Ionisation energies of elements decrease along the period

(B) Ionisation energies of the IIA group elements are less than that of the corresponding III A group elements.(C) Ionisation energies of group 15 elements are less than that of the corresponding group 16 elements.(D) Ionisation energy of Ga is greater than Al

9. The dominating factor responsible for the decreasing ionisation energies of the elements on moving down

the group is :

(A) atomic radius (B) type of electron to be removed

(C) the valence shell electron configuration (D) all of these

10. Which of the following order is not correct ?

(A) E(I) of Be > E(I) of B but E(II) of Be < E(II) of B

(B) E(I) of Be < E(I) of B but E(II) of Be < E(II) of B

(C) E(II) of O > E(II) of N

(D) E(I) of Mg > E(I) of Al

Match the column

11. Match list-I (atomic number of element) with list-II (position of elements in periodic table) and select

the corect anwer using the codes given gelow the lists :

(A) 1s2 (p) Show highest negative oxidation state

(B) 1s2 2s2 2p5 (q) Show highest first ionisation energy

(C) 1s2 2s1 (r) Show highest reducing power in aqueous solution.(D) 1s2 2s2 2p3 (s) Show highest electron affinity

(t) Show highest electronegativity

13. Column-I contains some increasing orders of various species and column-II has the properties of the

elements / ions Accordingly match the column-I and column-II

14. In Column-I, there are given electronic configurations of some elements Match these with the correct

metals given in Column-II :

(C) Second ionisation energy (r) Lutetium

(D) Inner transition element (s) Antimony

18. Match the type of elements / characteristic of the elements listed in Column-I with the correct element

listed in Column-II

(A) Highest 1st ionisation energy (p) Technitium

(B) Highest electronegativity (q) Lithium

(D) Strongest reducing agent (s) Fluorine

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19. The Column-I has certain details about the elements of s-, p- and d-block elements Match those with

the group number of the elements listed in Column-II

(A) An element whose fourth shell contains two p-electrons (p) 8th group

(B) An element whose valence shell contains one unpaired p-electron (q) 12th group

(C) An element which receives last electron in (n – 1) d-subshell (r) 14th group

(D) An element with the ground-state electron configuration [Ar]4s23d10 (s) 17th group

Assertion / Reasoning

DIRECTIONS :

Each question has 5 choices (A), (B), (C), (D) and (E) out of which ONLY ONE is correct.

(A) Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1.(B) Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1.(C) Statement-1 is True, Statement-2 is False

(D) Statement-1 is False, Statement-2 is True

(E) Statement-1 and Statement-2 both are False

20 Statmemt-1 : F atom has less electron affinity than Cl atom.

Statmemt-2 : Additional electrons are repelled more strongly by 3p electrons in Cl atom than by 2p

electrons in F atom

21 Statmemt-1 : Noble gases have highest ionization enthalpies in their respective periods.

Statmemt-2 : Noble gases have stable closed shell electronic configuration.

22 Statmemt-1 : Electron gain enthalpy of oxygen is less than that of fluorine but greater than that of

nitrogen

Statmemt-2 : Ionization enthalpy is as follows : N > O > F

23 Statmemt-1 : Cs and F combines violently to form CsF.

Statmemt-2 : Cs is most electropositive and F is most electronegative.

24 Statmemt-1 : Nitrogen has higher IE than that of oxygen.

Statmemt-2 : Nitrogen atom has smaller atomic size than that of oxygen.

25 Statement-1 : Electron affinity values of the 3rd period elements on extreme right of the periodic table

except noble gases are generally more than the 2nd period element of the same group

Statement-2 : Due to smaller atomic size of the 2nd period element, its electron density increases

which eases the addition of electron

26 Statement-1 : In a period noble gas has largest atomic radius.

Statement-2 : In case of noble gases vander Waal's radius is defined and there is much inter electronic

repulsions

27 Statement-1 : The 5th period of periodic table contains 18 elements not 32

Statement-2 : n = 5 ,  = 0, 1, 2, 3 The order in which the energy of available orbitals 4d , 5s and 5pincreases is 5s < 4d < 5p and the total number of orbitals available are 9 and thus 18 electrons can beaccommodated

True / False

28. Among K+, Mg2+ and Al3+ ions, Al3+ is the smallest one

29. The negative value of electron gain enthalpy of Cl > F because there is weak electron-electron

repulsion in the bigger 3-p sub-shell of Cl as compared to compact 2p-subshell of F

30. Formation of S2 – and Ar–, both require the absorption of energy

31. The following set of elements does not represent the correct order of electron affinity values

S > Se > Te > O

32. The size of the isoelectronic species is effected by electron-electron interaction in the outer orbitals