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Periodic Table, Periodic table, (Metals , metalloids and non-metals) -…
Periodic Table
Old classification
Dobernier's triads
Set of 3 elements
Law of triads
Newlands Octaves
Every 8th note resembles first
True up to calcium
Lothar Meyer's atomic volume curve
Atomic Volume vs atomic mass curve
1) Alkali metals top 2) Alkaline metals descending 3) Inert gas bottom 4) Halogens ascending
Mendeelev
At. Wt. = valency * eq wt.
Modern Periodic table
Mosleys law
sqrt. v = a(Z-b)
Terms
Period
7 periods
Group
18 groups
Have same properties
Representative
Bridge elements
Typical
Nomenclature of elements > 100
Electronic configuration of elements
Of periodic table
Across periods
Indicates 'n' for outermost shell
no. of elements in period = twice the no. of orbital being filled
Across groups
Similar valence shell electronic configurations
Type pf elements
s,p,d,f
p-block
together with s block are called representative elements
Characteristics
Have variable valencies
Are EN
Form covalent and ionic bonds
f-block
Characteristics
Have variable oxidation state (+3 most impo)
Also called inner transition
Form colored compounds and complexes
paramagnetic
Above 92 are all manmade (92-102)
d-block
Characteristics
Elements of group 3-12
Electronic config - (n-1)d^1-10 ns^1-2
Form mostly coloured ions
Have variable valencies and oxidation states
Paramagnetic (contain unpaired e)
Form coloured compunds and complexes
High density and MP
Form ionic as well as covalen where they are complexes
Form coloured compounds and complexes
Have vacant d - orbitals
If its transition then it from d - block but not vice versa
Transition elements have partially filled d block
Exception - Hg. Cd, Zn
s-block
Compounds are ionic except lithium
and beryllium
Characteristics
Are dimagnetic
Form colorless compounds
Good reducing agents
Low ionization enthalpies
Inert gases
Form compounds with F
Atmic radii very ;arge
GIOC
Periodic trends in properties of elements
Physical
Atomic radius
Types of radii
Covalent
Homodiatomic molecuel
r(c) = 1/2 bond length
Vander wall
Diameter of atom
Ionic
Radius of cation smaller tahn neutral
Radius of anion greater tahn neutral
Characteristics
Isoelectronic species
Radius inversely with Z/e ratio
Same no of electrons
Additive proeprty
Metallic
Half the distance seperaitng metal cores
Periodicity
For normal elements
Top to bottom - radius increases
Left to right - radius decreases
For inert gases
Largest radius in a period
Increases radius top to bottom
Screening effect
Intro
Calculation of sigma nad Z(eff) by slaters rule
Z(eff) = Total charge (Z) - screening constant
ns-np
d or f
Applications
Explains why electron enters 4s first than 3d
Explains why electron removes from 4s than 3d
Decreases of screening power
ns>np>nd>nf
Periodicity
Screening effect
Increases left to tight and top to bottom
Nuclear charge
Increases left to right
Decreases top to bottom
Zeff increases then IP decreases
Penetration effect
the ability of an orbital to attract an electron
decreases with ns>np>nd>nf
Pene efft increases then IP increases
IP
I enthalpy = I energy + 5/2*RT
Periodicity
Cs has lowest IE and most electropositive in PT
Left to ritgh
IP increases
Exceptions
Top to bottom
Exceptions
IP decreases
Importance
Elements with low IP are stronf reducing agents
Predicitng stable oxy states
Diff between IP is > 16 ev then lower oxy state is stable
Diff betewin IP < 16 ev then higher ocy state stable
Diff between IP is 10-15 ev then variable oxy state
Factors affecting IP
Size of atom increases - IP decreases
Z(eff) increases - IP increases
Screening effect increases - IP decreases
Half filled orfull filled shells - high IP
All values are positive
EA
EGE = - EA - 5/2* RT
Periodicity
Top to bottom - EA decreases
Left to right - EA decreases
Top to bottom
Satbility of metal decreases while activity increases
Reducing nature increases; oxisining nature decreses
Left to right
Satbility of metal increases while activity decreases
Reducing nature decreases; oxidising nature increases
1st EA can be +ve or -ve but 2nd EA is always +ve
Depends upon
Greater size of atom less the EA
High Z eff then high EA
Since ns is filled in 2nd group they have 0 EA
EA in 2nd period less than 3rd period
He has lowest EA among inert gases
Importance
Elements with high -ve value act as strong oxyidising agents
EN or EP
Property of an atom in bonded state
Periodicity
Top to botto,
EP INCREASES HWILE EN DECREASES
Left to right
EP decreases while EN increases
Exceptions
Factors affecting EN
Scales of EN
Paukling
muliken
Alfred rochow
Chemical
Valence or oxidation states
Top to bottom - remains the same
Left to right - 1 to 4 then decreases
Inert pair effect
Magnetic properties
Ferromagnetic
Paramagnetic
Dimagnetic
Oxides
Hydrides
Bond Length
Diagonal relatioship
Fajans rulw
Acid and bases
Periodic table
Intro
Old classification
Periodic table
Metals , metalloids and non-metals
