Atomic Structure of O level

1. Atomic Structure
Summary
Atom
~ Sub-atomic particles
- Mass - Charge
- NUCLEONS
 Isotopes :
-Behaviour of Sub-atomic particles
 Extra-nuclear Part :
- Shell - Subshells - Orbitals
- Shapes Of Orbitals
~ Definition
Page-1

2. Electronic Configuration :
o s p d f Notation
o Noble Gas Core
o Electrons-in-Boxes
~ Transition Elements [ 18Ar ] 4sx 3dy
 Ionization Energy :
- Definitions
- Types - Factors
- Atomic Radius - Nuclear Charge - Shielding / Screening
- Questions :
-Trend 1, 2 - Sudden Change - Graphs
Rules:
 Energy Rule
 Degenerated Orbital Rule
 Orbital Rule
Page-2
~ Ions Configuration

3. Atomic Structure
Atom
that can take part in a chemical reaction
~ Two parts
 Nucleus
 Extra nuclear part
~ Protons & Neutrons
~ Electrons
] NUCLEONS
23
𝑵𝒂11
Protons = 11 , Electrons = 11 , Neutrons = 12
Nucleons = 23
Symbol Relative Mass Relative Charge
𝐩𝟏+
𝒏𝟎
𝐞𝟏−
~ Smallest part of element
& Three Sub-atomic particles
1
2000
or
1
1860
or
1
1840
1-
1
1+
1
0
Atomic Structure Lecture- 1
AS Level
Chemistry

4. ~ Charge of any material depends on :
 Protons &
Electrons
o Three types of Charges
 Neutral
 Cationic
 Anionic
~ Protons equal to Electrons
~ Protons greater than Electrons
~ Protons less than Electrons
] Oxidation
] Reduction
~ Chemical Changes , control charge , ~
depend on Electrons .
~ Mass of an Atom depends on :  Protons & Neutrons
Nucleus
~ Physical Changes , depend on
Neutrons ( Nucleus )
X
 Only
Atomic Structure Lecture- 1
AS Level
Chemistry

5.  Isotopes :
Definitions : ~ Atoms of the same element
~ having same atomic number but
different mass number.
2 ~ Atoms of the same element
~ having same electrons &
protons but different neutrons.
1
1
1
1
In terms of Sub-
atomic particles
 Same Chemical properties
 Different Physical properties
~ same Electrons ( Valence )
~ different Neutrons
1H1
2H1
3H1
X H2O D2O
Mass Low High
B.P. Low High
2 H2O + 2 Na  2 NaOH + H2
2 D2O + 2Na  2 NaOD + D2
1
Atomic Structure Lecture- 2
AS Level
Chemistry

6. Behaviour of Sub-atomic particles in an
Electric Field
Ѳ1 & Ѳ2 Angle of Deflection : More
Factors:
 Charge of particle
 Mass of particle
 Electric field strength
X
~ More
~ Less
Ʇ- ve
+ ve
P Ѳ2 is greater than Ѳ1
Since electron is lighter
than proton
Ʇ Ѳ2
Ѳ1 no
p 1+
e 1-
Atomic Structure Lecture- 3
AS Level
Chemistry

7. ~ Relative Angle of Deflection ( RAD )
 RAD α Charge  RAD α
1
𝑀𝑎𝑠𝑠
RAD =
𝐶ℎ𝑎𝑟𝑔𝑒
𝑀𝑎𝑠𝑠
X Given Ѳ
a) 2H1
1+ b) 4He2
2+ c) 23Na11
1+ 19F9
1-
a ) RAD for = X 4 = 2𝑜
d)
d) RAD for 19F9
1- = − 1
19
X 4 = −
4
19
OR
4
19
but in
opposite
direction
Ʇ
Ʇ
Ѳ = 4 o
+ ve
- ve
1H1
1+
2H1
1+ 1
2
Atomic Structure Lecture- 3
AS Level
Chemistry

8.  Extra-nuclear Part :
~ Electrons ~ Circular paths
• Shells
– Quantum Shells / Energy Levels / Energy Bands
Definite amount of Energy –
Chemical Energy of e1-
= K.E. + P.E.
Motion
Distance
Shell
Name K L M N O P Q
Number 1 2 3 4 5 6 7
Shell Number = Principal Quantum Number = n
n= 1,2,3 ……. Ꝏ Value of n :
o Size of shell o Energy of shell
~ Large
~More ~ More
Number of Electrons in a
Shell = 2 n2
Atomic Structure Lecture- 4
AS Level
Chemistry

9. Within a Shell :
~ Electrons
-- Small groups
Subshells
–
/ Sub-Energy Levels
No. of Subshells
= Shell No.
}
e 1-
2 = 2 x 12
18
8
32
= 2 x 22
= 2 x 32
= 2 x 42
Shell
K = 1
L = 2
M = 3
N = 4
= Principal Quantum Number = n
Atomic Structure Lecture- 4
AS Level
Chemistry

10. Within a Sub-Shell :
~ Electrons -- Pair form
~ Pair of --- Orbital
e 1-
No . Of orbitals in a shell
2n2
2
OR n2
e1-
~ Tiny Magnet
eA
1-
eB
1-
Shell
K = 1
L = 2
M = 3
N = 4
Subshells
1 ~
2 ~
3 ~
4 ~
s2
6
10
14
p
s
s
s2
2
2
p
p
6
6
d
d
10
fX
Subshell ~ s
Orbitals
1 orbital
Subshell ~ p
Subshell ~ d
3 orbitals
5 orbitals
Field : - Electric - Static
- Magnetic - Moving
}
Atomic Structure Lecture- 4
AS Level
Chemistry

11.  Shapes Of Orbitals :
~ Shape / e1- Cloud / e1- Density
~ Sub-shell- p
- 6 e1- -------- 3 orbitals
- Equal E = Distance
- but Different Orientation
( px , py , pz )
Degenerated
Orbitals
x
y
z
x
z
y
~ Sub-shell- s
Atomic Structure Lecture- 5
AS Level
Chemistry
Without orientation

12. s - Orbital
Symmetrical
Sphere
Without orientation
2 – Lobed
Dumb-bell
p - Orbital d - Orbital
4 – Lobed
Dumb-bell
Atomic Structure Lecture- 5
AS Level
Chemistry

13.  Shapes Of s-Orbitals :
 Shapes Of p-Orbitals :
2s
Atomic Structure Lecture- 5
AS Level
Chemistry

14.  Electronic Configuration :
- THREE types
o s p d f Notation
o Noble Gas Core
o Electrons-in-Boxes
 THREE Rules
a) - Energy Rule
b) - Degenerated orbital Rule
c) - Orbital Rule
Nucleus 2 2 3 3 3
4 4
s s p s p d
s p
1
Energy increases
E4s
Is
Less
Than
E3d
- small size
/ More penetration
 1s 2s 2p 3s 3p 3d 4s 4p
OR
 1s 2s 2p 3s 3p 4s 3d 4p
1s 2s 2p 3s 3p 3d 4s 4p
Atomic Structure Lecture- 6
AS Level
Chemistry

15. 1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p
4s
3d
 4s is filled earlier
than 3d
Atomic Structure Lecture- 6
AS Level
Chemistry

16. 20Ca = 1s2 2s2 2p6 3s2 3p6 4s2
2 8 8 2
13Al = 1s2 2s2 2p6 3s2 3p1
9F = 1s2 2s2 2p5
19K = 1s2 2s2 2p6 3s2 3p6 4s1
 Noble Gas Core
2He 10Ne 18Ar 36Kr 54Xe 86Rn
20Ca = [ 18Ar ] n s2 4s2
/ [ 18Ar ]
13Al = [ 10 Ne ] 3 s2 p1
3
9F = [ 2 He ] s2 2
2 p5
~ Practice Work :
- First 20 Elements
~ At.No. 1 to 20
Atomic Structure Lecture- 6
AS Level
Chemistry

17.  Electrons –in – Boxes :
- Orbital OR OR
↓↑ ↓↑
1H =
2He =
3Li =
4Be =
5B =
6C =
7N =
8O =
9F =
10Ne =
1s
1s
1s
1s
1s
1s
1s
1s
2s
2s
2s
2s
2s
2s
2p
2p
2p
2p
Atomic Structure Lecture- 7
AS Level
Chemistry
~ Completely Filled Subshell
~ Half - Filled Subshell
~ Partially Filled Subshell
Most
Stable
1s 2s 2p
1s 2s 2p
Stable
Least
Stable

18.  Electronic Configuration :
~ Transition Elements - Central Part of the Periodic
Table
~ 1st Series - Atomic Number 21 to 30
21Sc 22Ti 23V 24Cr 25Mn 26Fe 27Co 28Ni 29Cu 30Zn
[ 18Ar ] x = 2 ( Except ‘Cr’ & ‘Cu’ ; x = 1 )
4sx 3dy
y = 1 - 10
}
21Sc =
24Cr =
29Cu =
[ 18Ar ]
[ 18Ar ]
[ 18Ar ]
4s1
4s2
4s1 3d10;
3d5 ;
3d1 ; 4s
4s
4s
3d
3d
3d
4s2
4s2
3d4
3d9
X
X
X
X


Atomic Structure Lecture- 8
AS Level
Chemistry

19.  Electronic Configuration :
~ Ions + ve
- ve
2
1 -------- Loss of e 1-
-------- Gain of e 1- }~ Valence Shell
20Ca2+ = 1s2 2s2 2p6 3s2 3p6
26Fe2+ =
35Br1- =
26Fe =
[ 18Ar ]
[ 18Ar ] 4s2
4s
3d6
3d6 3d6
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6
Atomic Structure Lecture- 8
AS Level
Chemistry

20.  Ionization Energy :
Ionization -
Oxidation
1
2 Reduction
- ‘E’ involved
- ‘E’ involved
----------- Ionization Energy
----------- Electron Affinity

 All the Materials can lose e1-
 All the e1- can be lost ~ Plasma
X ( s ) X ( g )
Heat
Sublimation
X1+
( g ) +
Heat
Ionization
e1-
X1+
( g ) + e1-
e1-
e1-
X1+
( g ) X2+
( g ) +
X3+
( g ) +
X2+
( g )
X0
( g ) ΔΗie1
ΔΗie2
ΔΗie3
+
Atomic Structure Lecture- 9
AS Level
Chemistry

21. ( ΔΗie1) Na
( ΔΗie1)
Na( g ) Na1+
( g ) +
H2O( g )
H2O1+
( g ) +
H2SO4
2+
( g )
H2SO4
3+
( g ) +
( ΔΗie3)
H2O
H2SO4
e1-
e1-
e1-
( ΔΗie2) Ca Ca1+
( g ) Ca2+
( g ) +
e1-
Ca1+
( g ) Ca3+
( g ) +
M4+
( g ) M7+
( g ) +
2 e1-
3 e1-
~ Sum of 2nd , 3rd I.E. - Ca
~ Sum of 5th , 6th , 7th I.E. - M
~ Write An Equation for the 1st I.E. of Oxygen.
~ Write An Equation for the 1st I.E. of Oxygen Gas.
O2(g) O2
1+
(g) + e1-
O1+
(g) + e1-
O(g)
Atomic Structure Lecture- 9
AS Level
Chemistry

22.  Ionization Energy :
- Definition :
1 X1+
( g ) + 1 e1-
1 e1-
1 e1-
1 X1+
( g ) 1 X2+
( g ) +
1 X3+
( g ) +
1 X2+
( g )
1 X0
( g ) ΔΗie1
ΔΗie2
ΔΗie3
 The Enthalpy Change
 When One mole of e1- is removed


Ca1+
( g )
Ca2+
( g ) + e1-
~ KJ. mol -1
-Endothermic
 ΔΗie1 ΔΗie2 ΔΗie3
˂ ˂ …………
 Applications :
- Reactivity - Valency - Distribution of e1-
X
O
O
O
O
O
O
O
O
O
O
O
O
N
Atomic Structure Lecture-
10
AS Level
Chemistry

23.  Factors ( Ionization Energy ) :
- Atomic Radius
1
2
3
- Nuclear Charge
- Shielding / Screening
- Atomic Radius
1
3Li = 2,1
11Na = 2,8,1
19K = 2,8,8,1
2 - Nuclear Charge
Number of p1+
3 - Shielding / Screening = Repulsion
- Intervening shells / e1-
- Reactive Metal = Low I . E. =
Large Radius ; Low N.C. ; More Shielding
Atomic Structure Lecture- 11
AS Level
Chemistry
3Li 4Be 5B 6C 7N 8O 9F 10Ne

24. 3Li 4Be 5B 6C 7N 8O 9F 10Ne
1 2 3 4 5 6 7 8
Group :
~ Period # 2:
 Questions :
1. Trend of I.E. Across the Period
2,1 2,2 2,3 2,4 2,5 2,6 2,7 2,8
1+ 2+ 3+ 4+ 5+ 6+ 7+ 8+
o Number of Shells / Shielding remains same
o Nuclear Charge increases
o Nuclear Force / Pull increases
o Atomic Radius decreases
o I .E. increases
o Nuclear Charge increases
( Ionization Energy )
Atomic Structure Lecture-
12
AS Level
Chemistry

25. 3Li = 2,1
11Na = 2,8,1
19K = 2,8,8,1
Q.2. Trend of I.E. Down the Group
o Number of Shells / Shielding increases
o Increase in Nuclear Charge cancels
by increased Shielding
o Nuclear Force / Pull decreases
o Atomic Radius increases
o I .E. decreases
o Number of Shells / Shielding increases
Atomic Structure Lecture-
12
AS Level
Chemistry

26. - Q.3. I.E. values Vs Order of e1- removed for the Element
Sodium , Na :
11Na = 1s2 2s2 2p6 3s1
e1- Number Subshell
1
2-7
8-9
10-11
3s
2p
2s
1s
Three Changes :
1 ~ Sudden Change
2 ~ Slight Change
3 ~ Steady Change
I.E.
Values /
KJ.mol-1
1 2 3 4 5 6 7 8 9 10 11
e1- Removed Number
X
X X X
X
X
X
X X
X X
---------- Change of Shell
---------- Change of Sub-Shell
---------- Change of Orbitals within a Sub-Shell
- No. of e1- removed before
1st sudden Change = Valence e1- = Group Number
}1
3
}2
} 1
3
3
Atomic Structure Lecture-
13
AS Level
Chemistry

27. Q.4.The For Element X------ K.J .mol -1
First few I.E. Values
578 , 1930 , 2780 , 9200 , 11280 , 14500
i) Group # 3
ii) Formula of Oxide X
O
O
O
X3 O2
= X2O3
/ Chloride
XCl3
iii) s2 p1
n n
Q.5. ~ Element M ------------ K.J. mole-1
430 , 920 , 1830 , 2830 , 9660 , 11220
Q.6.
1060 , 1907 , 2920 , 4960 , 6275 , 21265 , 25431
~ Element X ------------ K.J. mole-1
A XCl
B XCl2
C XCl3
D XCl4
Atomic Structure Lecture-
13
AS Level
Chemistry

28. Q.7.Sketch a Graph for 1st I.E. Values Vs Atomic Number
for the elements of Period # 2.
~ Period # 2:
~ Period # 3:
3Li 4Be 5B 6C 7N 8O 9F 10Ne
11Na 12Mg 13Al 14Si 15P 16S 17Cl 18Ar
3 4 5 6 7 8 9 10
Atomic Number
1st
I.E.
Values
KJ.mol-1
X
X
X
X
X
X
X
X
Li
Be
B
C
N
O
F
Ne
( Period # 3 )
II III V VI
~ Regular repeating pattern of properties across a period
 Periodicity
O
R
Log
I.E.
Values
Atomic Structure Lecture-
14
AS Level
Chemistry
4 Be = 1s2 2s2
5 B = 1s2 2s2 2p1
7 N = 1s2 2s2 2p3
8 O = 1s2 2s2 2p4

29. Atomic Number
1st
I.E.
Values
KJ.mol-1
X
X
X
X
X
X
X
2 4
5
6
7X
8
3
1
X
X
X
X
X
X
X
X
1
2
3
4
5
6
7
8
Atomic Number
I.E.
Values
X
X
X
X
A
B
C
D
~ Sudden Change
= Change Of Shell
= Change Of Period
Q.7. Give Reason , why
( 1st I.E. )Na is LESS than ( 1st I.E. )Mg
But ( 2nd I.E. )Na is MORE than ( 2nd I.E. )Mg?
11Na
12Mg
= 1s2 2s2 2p6 3 s1
= 1s2 2s2 2p6 3 s2
Atomic Structure Lecture-
14
AS Level
Chemistry