E-StoreINORGANIC 3(S-BLOCK SIMPLIFIED)
10 Feb 2008 21:48:11 IST
INORGANIC 3(S-BLOCK SIMPLIFIED)
S-BLOCK
Basic definations:
1A Alkali metals: Their oxides/hydroxides are strongest bases irresepective of periods.
1A Alkali metals: Their oxides/hydroxides are strongest bases irresepective of periods.
2A Alkaline earth metals: Because of their carbonates they are most abundant in earth's crust and basic in nature.
PHYSICAL PROPERTIES:
1. Atomic size:
1A > 2A > d-block
2. Sonority is the property to produce sound for longer time due to collision b/w the atoms if once hammered
3.High conductivity: due to presence of free electrons,ions and low Ionization energy
4. LUSTROUS BEHAVIOUR: Due to oscialltion of free electron by absorption of energy from photons
5. Metallic bond strength decreases downward
Metallic bond strength 
1/metallic character number of unpaired electron
1/metallic character number of unpaired electron6. Softness: It decreases left to right. 1A are softest metals due to weakest metallic bond strength or due to crystalline properties. Softness increases downward.
7. Brittleness: It decreases from right to left. Hence these s-block metals are very very less brittle.
Brittleness is the separtion of layers of the particles from the crystal structure by applying the force at a point.
U cn also undrstnd like this: Metal Jitna soft hoga utna hi mushkil hoga uski layers ko separate karna.
8. Crystal structure:
1A similar crystal lattice.
2A dissimilar crystal lattice.
1A physical properties show regular trend
2A phys. prop. show irregular trend.
9. 1A: melting and boiling point decrease downard regularly due to decrease in metallic bond strength
2A: MP and BP decreease dwnwrd irregularly due to different crystal structures.
The BP and MP of s-block metals is less than d block metals due to stronger metallic bond strength in d block elements.
10. DENSITY: It increases downward due to poor shielding effect and increase in atomic mass.
1A Li<K<Na<Rb<Cs
2A Ca<Mg<Be<Sr<Ba
Li, K and Na are lighter than water
K<Na and Ca<Mg (density) due to presence of d orbital
there is SUDDEN EXPANSION in volume of K and Ca
therefore their density is low.
Be has high density because of different LATTICE STRUCTURE
The density of d-block metals is greater than s-block metals due to low atomic mass and high volume of s-block metals...
10. PHOTOELECTRIC EFFECT:
In all metals of s block only K, Rb, Cs give photoelectric effect. They are used in photoelectric effect due to high Ionization energy.
11. FLAME TEST:
s-block salts like NO3-, NO2-, SO42-etc...
are heated on bunsen burner the salt absorbs heat radiations and then releaes energy which belongs to visible part of the spectrum which produces colours. On the basis of colour we can decide the elements..
NOTE: Be and Mg dunno give flame test due to high IE.
Platinum wire is taken due to its inertness and SEMI-SOLID form is taken of the salt due to low IE.
Halides are taken because of emission of high volatile radiation.
_______________________________________________________
Li Crimson Red
Na Golden Yellow
K Purple/lilac/plane violet
Rb violet
Cs Blue
NOTE: LILAC colour of K has been asked in JEE
Be X
Mg X
Ca Brick
Sr Crimson Red
Ba Apple Green
NOTE: wavlength increases downward and frequency upward.
__________________________________________________________
All S-block compounds are dimagnetic(exceptions alwys dere)
FLAME TEST is significant for s-block elements because all elements are white in colour and water soluble...
______________________________________________________________
CHEMICAL PROPERTIES:
1. Chemical reactivity:
Q. What happens when Na is left open in air ?
A. Na in air gives Na2O
Na2O comes in contact of water present in atmosphere and it fomrs NaOH
NaOH comes in contact with carbon dioxide of air and forms Na2CO3.
Na forms carbonates at end.
Metals like Fe and Al loose their lusturous behaviour due to formation of oxides.
All s-block elements follow the same reaction.
Therefore they can't be kept free in air as they are too reactive.
Hence they are stored in organic solvents like Carbon Tetrachloride, pyridene, toulene, benzene except Be, Mg and Li
Be and Mg form stable layer of oxides. Thus they can be kept freely in water or air.
IMP: Li is stored in wax. it can't be STORED IN KEROSENE because its density is less than that of kerosene. ( IT FLOATS ON THE SURFACE OF KEROSENE)
___________________________________________________________
SOLUBILITY:
The solubility of compounds of s-block elements with NO3-,HCO3-, OH-, H-, O2- and many other anions INCREASES DOWN THE GROUP.
FOR all 1A compounds the SOLUBILITY WILL INCREASE DOWN THE GROUP (except for Chlorides...itz an exception cn't do much about it).
The same fate will follow for 2A compounds....
BUT THERE ARE IMPORTANT EXCEPTIONS OF COMPOUNDS WHICH HAVE TO BE LEARNED:
Carbonates, MnO4-, Sulphates.
in these compounds the solubility decreases downward (ONLY 2A)
The reason is in these compounds Lattice energy > Hydration energy.
__________________________________________________________
please do comment....hpe it helps ya....if i get gud comments nd if ya say i will post the remaining part of the chapter (all reactions, exceptions)....
Comments (13)
Swati
Blazing goIITian
Joined: 3 Aug 2007 22:20:01 IST
Posts: 415
10 Feb 2008 21:52:21 IST
Like
0 people liked this
good job !!!
10 Feb 2008 22:54:07 IST
Like
0 people liked this
hey gr8 job man! pls try 2 put up p block.......plzzzzzz
11 Feb 2008 11:26:53 IST
Like
0 people liked this
fantabulous.........
realy ur article writing technique is very cool and nice..........
i really enjoyed reading this article......... much needed 1 ..thnx
realy ur article writing technique is very cool and nice..........
i really enjoyed reading this article......... much needed 1 ..thnx
16 Feb 2008 12:10:12 IST
Like
0 people liked this
nice collection
but most of d concepts written above r not at all r required 4 preparing 4 jee(chem ncert is more than sufficient 4 such topics)
but most of d concepts written above r not at all r required 4 preparing 4 jee(chem ncert is more than sufficient 4 such topics)
3 Apr 2009 15:59:23 IST
Like
0 people liked this
hey man cool......please post more on inorganic chemistry i am very weak in inorganic chemistry and need help urgently.....
Free Sign Up!
Preparing for IIT-JEE ?
Arihant Revision Package for IIT JEE - Books, Practice Tests + Rank Predictor
@ INR 1,995/-
For Quick Info
|
|
|
|
|
| 35,229,755 Engineering Questions Attempted |
6,69,530 Visitors Monthly |
79 Engg. Exam Covered |
515 Students Currently Online |
Connect with Us  |
 |
Vriti Communities
Privacy Policy © Vriti 2011