Students can go through TS Inter 2nd Year Chemistry Notes 6th Lesson P-Block Elements will help students in revising the entire concepts quickly.
TS Inter 2nd Year Chemistry Notes 6th Lesson P-Block Elements
→ Group 15 elements include Nitrogen, Phos-phorus, Arsenic, Antimony and Bismuth.
→ Nitrogen and Phosphorous are non-metals, arsenic and antimony are metalloids. Bismuth is a typical metal.
→ Nitrogen is inert due to high bond dissociation enthalpy of N = N.
→ Stability and basicity of hydrides decreases from NH3 to BiH3.
NH3 > PH3 > ASH3 > SbH3 > BiH3
→ Pentoxides are more acidic than trioxides N2O5 > N2O3.
→ Pentahalides are more covalent than trihalides because the element in the higher oxidation state exerts more polarising power.
→ Ammonia is prepared by Haber s process. N2, and H2, combine to give ammonia. Low tem¬perature and high pressure are required for high yield.
→ White phosphorus consists of tetrahedral P4 molecules held by van der Waal’s forces.
→ Holme’s signal uses calcium carbide and calcium phosphide.
→ Oxoacids of phosphorus are
-
- Orthophosphoric acid H3PO4
- Pyrophosphoric acid H4P2O7
- Orthophosphorus acid H3PO3
- Hypophosphorus acid H3PO2
→ Oxygen, Sulphur, Selenium, Tellurium, and Polonium constitute Group 16 of the periodic table. They are known as chalcogens as they are ore forming.
→ Oxygen cannot show higher oxidation state due to non-availability of d-orbitals in outermost shell.
→ Stability of hydrides decreases H2O > H2S > H2Se > H2Te > H2Po.
→ The acidic nature of hydrides of Group 16 increases. H2O < H2S < H2Se < H2Te < H2Po.
→ Molecular oxygen is paramagnetic. It contains two unpaired electrons in antibonding π* orbitals.
→ Ozone is prepared by passing silent electric discharge through pure and dry oxygen.
→ Stable form of sulphur at room temperature is rhombic sulphur.
→ Monoclinic sulphur is stable above 369K. At 369K both Rhombic and Monoclinic sulphur are stable. This temperature is called transition temperature.
→ H2SO4 is prepared by contact process.
→ H2SO4 is needed for manufacture of hundreds of compounds and also in manufacture of fertilisers.
→ Fluorine, Chlorine, Bromine, Iodine and Astatine are members of Group 17. They are known as halogens.
→ All these elements have ns2np5 electronic configuration. .
→ All the halogens are highly reactive. They behave as oxidising agents.
→ Stability of Hydrogen halides decreases down the group due to decrease in bond dissociation enthalpy.
HF > H – Cl > H-Br > H – I
→ The acidic strength of hydrogen halides varies in the order HF < HCl < HBr < HI. → HF has highest boiling point and it is the only liquid. Others are gases. Order of B.Ps. HF > HI > HBr > HCl
The high boiling point of HF is due to hydrogen bonds among HF molecules.
→ In OF2 and O2F2 oxygen has + 2 and +1 oxida¬tion states. They are termed oxygen fluorides. O2F2 oxidises plutonium to P4F6. It is used in removing plutonium as P4F6 from spent nuclear fuel.
→ Chlorine forms Cl2O, ClO2, Cl2O6 and Cl2O7.
ClO2 is used as a bleaching agent for paper Pulp.
→ I2O5 is a very good oxidising agent and is used In the estimation of carbon monoxide.
I2O5 + 2CO → Ir5CO2
→ Halogens combine amongst themselves to form a number of compounds known as Interhalogens. They are classified as :
AX, AX3, AX5, AX7 where A is bigger halogen.
→ Interhalogens are more reactive than halogens. A – X bond is weaker than X – X bond.
→ ClF3 is T-shaped. BrF5 is square pyramidal and IF. has pentagonal bipyramidal.
→ Among the different oxoacids of chlorine, the acidic character follows the order HOCl < HClO2, < HClO3, < HClO4.
→ The acidic character of hypohalous acids varies as HClO > HBrO > HIO.
- ICl + H2O → HCl + HOI
- ICl3 + 2H2O → 3HCl + HIO2
- BrF5 + 3H2O → 5HF + HBrO3
→ Group 18 consists of six elements. They are Helium, Neon, Argon, Krypton, Xenon and Radon.
→ All noble gases occur in atmosphere except radon.
→ Their atmospheric abundance in dry air is – 1 % by volume of which argon is the major constituent.
→ The commercial source of Helium is natural gas.
→ Xenon and Radon are the rarest elements of the group.
→ Radon is obtained as a decay product of
22688Ra → 22686Rn+ 42He
→ All noble gases have general electronic con-figuration ns np6 except Helium which has 1s2.
→ They have large positive values of electron gain enthalpy.
→ Helium has the lowest boiling point (4.2K).
→ Among a few compounds of Krypton (KrF2) has been studied in detail.
→ Xenon forms three binary fluorides XeF2, XeF4 and XeF6 by the direct reaction under appropriate experimental conditions.
→ Helium is non-inflammable and light gas. It is used in filling balloons for meteorological observations. It is also used in gas cooled nuclear reactors.
→ Neon is used in discharge tubes and fluoroscent bulbs.
→ Argon is used mainly t0 provide an inert atmosphere in high temperature metallurgical processes and for filling electric bulbs. It is also used in labs for handling air sensitive substances.
→ There are no significant uses of Xenon and Krypton. They are used in light bulbs designed for special purposes.