Most important point of chemistry class 10th and 12th important

Characteristic Feature of Halogen Family:

1. General configuration – n * r ^ 2 * n * rho ^ 32. All are non metal due to high electronegativity.3. All are diatomic molecule.

4. Halogens are coloured (due to absorption of visible light).

Read more:English essay class 10th: महत्वपूर्ण ऐसे कक्षा 10वीं और 12वीं

(gas) absorbs violet light (high energy) & I (solid) absorbsyellow light (lower energy) thus are found to be greenishyellow & violet colour respectively. Cl is deep greenishyellow gas & Br is Brown liquid.

5.6.Flurine exhibit only oxidation state. Other familymembers shows-1 to +7 oxidation state.They are oxidizing agent and this property decreases as we


go down the group.

They form Hydra acid of the type HX, Acidic strength of

8.HX increases on moving down the group which can beexplained on the basis of Born Haber Cycle.Due to absence of d-orbital, F does not form oxyacids (pr-dit bonding is not possible). Other halogens form oxyacidsof the general formula HXO, HXO,, HXO, & HXO, Thestability of oxyacids is a direct function of atomic numberof halogen atom i.e. HIO, > HBrO, > HCIO, alkali metalsalts of HCIO, can be used as an explosive.

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9. ICI is known as Wij’s Reagent.10. In presence of mositure they act as a bleaching agent.X_{1} + H_{1}*O = HX + HXO0+ colour = Colourless/Colour change

HXO + HX = 0

They bleaches colour nascent through oxygen and therefore actas a permanent bleaching agent. Liberation of nascent O takesplace in presence of moisture and therefore dry X_{2} does not actas a bleaching agent. Due to electronegativity difference thereactivity order of different halogens obey the order as follows:-F(explosive) > Cl > Br > I Thus oxidizing/Bleaching order obeythe following order-

Cl = Strong Bleaching /oxidizing agent.Br = Mild oxidizing/Bleaching agent.I = Very little action (Almost negligible)

Inter halogen compounds-Due to electronegativity difference,halogen form binary compounds (AB type) with different halogen.Such compounds are called inter halogen compounds. In suchcompounds A is always bigger atom and the value of n varies(found to be 1, 3 and 7) value of n increases with increases inatomic number of A. Ex-

n = 1 when A = Cl Bror Ie.g., CIF, BrF, BrCI, ICI, IBr (Linearstructure, gas)

Except He, all family members have highly stable n configuration in the outer shell. Thus, these elements ha to either lose, gain or sof other electrons with combing is zero. These elements are thus chemically inen their atoms valency All the orbitals in the atom of these elements are doubly occupied i.e. elements are not available for sharing. Hence, these elements can’t form covalent bond. these element are very high. Hence the atom capacity

Characteristics of Inert Gas:

Important Points

of these elements have no tendency to lose electrons from the outer most orbit as to form cation. The Ea-values of these elements are zero. Hence the atoms of these elements have no tendency accept electronie

They all are colourless, odourless and tasteless gases. These gases do not burn and also do not help in burning


These gases are sparingly soluble in water.

xcept He, these gases can be adsorbed by coconut charcoal at suitable temperature. The atomic radii of these gases are very large and increases

on moving down the group. 12. These gases give a characteristic spectra by which they can be easily identified.

These gases have fairly high electrical conductivity, they produce characteristics coloured lights when an electrical discharge is passed through them at low pressure

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