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SHOBHIT NIRWAN's
DESIGNED

CLASSIFICATION OF ELEMENTS
&
PERIODICITY IN PROPERTIES


NEW NOTES FOR CLASS 11 2022 EXAMS

OVERVIEW OF THE CHAPTER
1
...
Dobernier Law
3
...
Newlands Law of Octaves
5
...
Mendeleev Classification of Elements
7
...
Modern Periodic Law
9
...
IUPAC Nomenclature for Elements
11
...

(i) s – block Elements
(ii) p – block Elements
(iii) d – block Elements
(iv) f – block Elements
12
...
Classification: Metals, Non – metals & Metalloids
14
...
Valency, Covalency & Oxidation State
16
...
Anomalous Properties of Second Period Elements

1
...

• Elements coming after 92 are known as “Trans Uranic Elements” or
synthetic elements and they are radioactive
...
Dobereiner Law of Triads:• A triad is certain group of 8 elements with similar properties
...

• Also the properties of middle element were in b/w those of the other two
...

Ex: (i) Li, Na, K (ii) S, Se, Te
(iii) Cl, Br, I (iv) Ca, Sr, Ba

3
...

• Made cylindrical table of elements displaying recurrence of properties
...
Newland’s Law of Octaves:
• Arranged elements in increasing order of atomic weight
...

• The relationship was just like every eighth note that resembles the first in
octaves of music
...


5
...

Atomic weight = at
...
alkali metals ( Na, K , Rb , Cs , Fr ) are at peaks of curves
...
alkaline earth metals (Be, Mg, Ca, Sr, Ba) are at descending part of curve
...
Halogens are ascending part of curve (F,Cl, Br,I)
4
...

अब होगी असली हीरो की एं ट
...
Dimitri Mendeleev
Dobernier ने start की थी कहानी और पूरी Mendeleev ने की l
चलो Mendeleev classification समजते चलो समाजते

6
...
Also known as short form of periodic table
...
he relied on the similarities in the empirical formulas and properties of the
compounds formed by the elements
...
He not only followed the order of atomic weights but also placed elements
with similar properties
...
Vertical columns – groups (9 groups)
Horizontal rows – periods (7 periods)
4
...

5
...

6
...

7
...

(i) Iron, Cobalt, Nickel
(ii) Ruthenium, Rhodium, Palladium
(iii) Osmium, Iridium, Platinum
8
...

9
...
He corrected the weights of Beryllium, Iridium and Osmium

Merits:1
...

2
...


Demertis:1
...

Ex: (i) Ar - K (ii) Co – Ni (iii) Te – I (iv) Th – Pa
2
...


3
...

4
...

5
...


7
...

• Atomic number increases, frequency of x-rays increases
...
Modern Periodic Law:
Physical & chemical properties of elements are periodic functions of their
atomic number
...
is the number of protons or the number of electrons in a
neutral atom
...
Long Form of Periodic Table:
• Bohr constructed the long form of periodic table
...

• There are 18 groups ( vertical columns) and 7 periods ( horizontal rows)
...

• The electron by which an element differ from its previous element is
called “differentiating electron”
...

• Followed by Afbau- Rule (n+l) order values
...
corresponds to the highest principal quantum number (n) of
elements in the period
...

• The 7th period is incomplete and like the 6th period would have a
theoretical maximum of 32 elements
...


Groups:
• Contains 18 vertical columns which are divided into main groups &
subgroup at I A & to VII A, 0 groups and VIII B, IV B, VB, VI B, VIIB, VIII B, IB
and II B groups
...
IUPAC Nomenclature for Elements(z>100)
• The roots are put together in order 9 digits which make up the atomic no
...

Digit
0
1
2
3
4
5
6
7
8
9

Latin
Nil
Un
bi
Tri
Quad
Pent
Hex
Sept
Oct
enn

Word
n
u
b
t
q
p
h
s
o
e

Q1)What would be the IUPAC name and symbol for the element with
atomic number 120?
Ans: The roots for 1, 2 and 0 are un, bi and nil, respectively
...

Q2)How would you justify the presence of 18 elements in the 5th period
of the Periodic Table?
Solution
When n = 5, l = 0, 1, 2, 3
...
The total number of
orbitals available are 9
...


11
...

• This similarity arises because these elements have the same number of
electrons in their outermost shells
...

a) s- block elements b) p – block elements
c) d - block elements d) f – block elements

(i) S – block Elements:
• Differentiating electron enters into s – orbtial
...

• Readily lose outermost electron and form +1 ion or +2 ion
...

• Never found in free state due to high reactivity
...

Arranged in 6- groups they are form III A to VII A and 0 – groups (or)
13-18 groups
...

Outer most orbital is completely filled in noble gases
...


Q3) Helium belongs to S block group elements but still it is placed in p block
...

(iii)
d – Block
•
•
•
•
•

Differentiating electron enters into inner d orbitals (n-1)d subshell
...

General electronic configuration (n-1)d1-10 ns1-2
...


• Show variable valencies , from coloured ions, para magnetism, and also
used as catalysts
...
They do not show properties of
transition elements and have (n-1)d10 ns2
...

• Differentiating electron enters into f – subshell of anti – penultimate i
...

4f series → lanthanoids
5f series → actinoids
• Actinoids elements are radioactive
...

• They have properties similar to d – block elements
...

Q4) The elements Z = 117 and 120 have not yet been discovered
...

Solution: the element with Z = 117, would belong to the halogen family
(Group 17) and the electronic configuration would be [Rn] 5f 146d107s 27p5

...


12
...
He, Ne, Ar, Kr, Xe, Rn are called as inert gases (18th group)
2
...

3
...

4
...

5
...


Type 2: Representative Elements
1
...

2
...

3
...

4
...
Metals, Non-metals and metalloids are present
...
In these elements the ultimate and penultimate shells are incompletely filled
...
Elements which have incomplete or partially filled ‘d’ orbital are called as
transition elements
...
General electronic configuration is (n-1)d1-9 ns0-2
4
...

Type 4: Inner Transition Elements:
1
...
The f-block elements are called as inner transition elements
...
General configuration : (n-2)f1-14 (n-1)0 (or)1 ns2
4
...
Most of them are radioactive elements
4f series → lanthanoids
5f series → actinoids

13
...

Present at left side of Bordering this line and
periodic table(usually)
running
diagonally
across periodic table
Usually solid at room Show properties of both
temperature
(except metals and non- metals
mercury)
called as metalloids

Non – Metals
Located at top right
hand side of periodic
table
...

With low melting and
boiling points
...

Brittle neither ductile
not malleable
...


KK3B:
3B:

Pseudo
PseudoInert
InertGas
GasElectronic
ElectronicConfiguration:
Configuration:

- Presence
Presenceofof18e
18ein
inoutermost
outermostshell
shellisiscalled
calledpseudo
pseudoinert
inertgas
gasconfiguration
configuration
Ex:
Palladium
...


Elements के बारे म' तो एक idea आगया… हम लोग का next step उनके properties
जानने का है
...
Trends In Physical Properties:
There are numerous physical properties of elements such as Melting point and
Boiling point, heat of fusion and vapourisation etc
...

• It refers to both covalent or metallic radius depending on the element
...
Nature of bonding
2
...
Oxidation Number
4
...
Bond character

• Measured in angstrom, nanometer, picometer units
...

• Atomic radius increases with increase in atomic number down the group
due to the addition of shells as number of outer electrons increases
...


Q5) Why atomic radius decreases across period??
Answer:- it is due to the increase in nuclear charge increases with increase
in atomic number and the outer electrons, within the period are in the same
valence shell
...


b) Ionic Radius:
• It is the distance between the nucleus and the electron in the outer most
shell of its ion
...

• In anion → size is larger than parent atom, due to addition of electrons,
results in increase in repulsion among electrons and decrease in nuclear
charge
...

• In isoelectric species, the size increases with increase of negative charge
& decreases with increase in positive charge
...

Ans: Metallic character increases down a group and decreases along a period as
we move from left to right
...


Q7)Identify isoelectronic species
a) Mg+2 & Al+3 c) N-3 & C-5
b) Al+2 & Mg+2+ d) N-3 & C-4
Answer:- (a) & (d) are isoelectronic species
...
of electron = 12 – 2 = 10 eAl+3 → atomic number of Al = 13
No
...
of electron = 7 – (-3) = 10 eC-4 → atomic number of C = 6
No
...

Consequences:- 1
...

2
...

Solution: Atomic radii decrease across a period
...
Among isoelectronic species, the one with the larger positive nuclear
charge will have a smaller radius
...

Basic strength of hydroxides : as the size of the lanthanide ion decreases from
Ce+3 to Lu+3 , the covalent character of M-OH bond increases and hence the basic
strength decreases
...


c)Ionization Enthalphy / Ionization Energy:
• The minimum amount of energy required to remove the loosely bonded
electron from the outermost shell form an isolated neutral gases is called
as ionization potential
...
E1 → M(g) + 1e• It is an endothermic process , energy is always required to remove
electrons from an atom hence ionization enthalpies are always positive
...

• Energy required to remove an e- form unipositive gaseous ion to convert
into dipositive gaseous is called second ionization potential
...
E2 → M(g) + 1e-

• I
...
atomic size
2
...
screening effect
4
...

• Atomic Size α 1/ ionization potential
Due to decrease in nuclear charge
• I
...
P increases
-ve charge on anion increases, I
...
P values due to completely filled orbitals
...
P & atomic number inert gas are at maxima & alkali
metals appear at minima position
...
P decreases
...
P ↑
• In groups from top to bottom I
...
Predict whether
the first ∆i H value for Al will be more close to 575 or 760 kJ mol–1 ? Justify
your answer
...
The value for Al should be
lower than that of Mg because of effective shielding of 3p electrons from the
nucleus by 3s-electrons
...

X(g) + e- → X- + EA1
X(g) + e- → X-g

Δ H = -EA1

• It is an exothermic process
...
Thus energy is called as second electron
affinity EA2
...

• Group 17 elements have very high E
...

• Noble gases have large positive electron gain enthalpies because the
electron has to enter the next higher principle quantum level leading to a
very unstable electronic configuration
...

• In period from left to right, EA increases due to decrease in size of atom
& increase in nuclear charge
...
Most of the electron gain enthalpy – Cl across the period EA increases
...
least electron gain enthalpy – P

e) Electronegativity:
• The tendency to attract shared pair of electron towards itself in a
molecule is called as Electro negativity (E
...

• E
...
It has no unit
...
(4
...
N also
increases
...

• EN increases across period from left to right & decreases down the group
• Non – metallic elements have strong tendency to gain electron
...


15
...
of
oxygen atoms that can combine with one atom of that element
...

• More than one valency then it is called as variable valencies
...


(ii)Covalency:
• The number of covalent bonds formed by an element
...

Q12)Predict the formula of component formed b/w an element X of group 13
& Y of group 16
...

Solution:
(a) Silicon is group 14 element with a valence of 4; bromine belongs to the halogen family
with a valence of 1
...

(b) Aluminium belongs to group 13 with a valence of 3; sulphur belongs to group 16
elements with a valence of 2
...


(iii)Oxidation State:
• The positive charge with which an atom appears in a compound is called
oxidation state
...


16
...
This is called diagonal relationship
...
Anamoulous Properties of Second Period Elements:
Reasons:- 1
...
large (charge/ radius) ratio
3
...
Absence of vacant orbitals

Effect: Ex (i) lithium, Beryllium forms covalent compounds, rest of group
memebers form ionic compounds
...


Q15) Are the oxidation state and covalency of Al in [AlCl(H2O)5 ] 2+ same
? Solution: No
...


Q16) Show by a chemical reaction with water that Na2O is a basic oxide
and Cl2O7 is an acidic oxide
...
Na2O + H2O → 2NaOH Cl2O7 + H2O → 2HClO4
...




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