JEE MAIN 2020 NEWS
NATIONAL LEVEL ONLINE TEST
Inorganic Chemistry has equal weightage compared to Organic and Physical Chemistry, but it is relatively simple, scoring and requires less time. Moreover, most of the questions come directly from NCERT. Study in detail to be clear with the concepts of bonding and coordination chemistry. NCERT will teach you all about block chemistry and its reactions. p-Block elements is one of the most important topics asked from Inorganic Chemistry.
The chapter on p-Block elements carries a weightage of around 6% in the Chemistry section in JEE Main. Therefore, 1-2 questions are sure to be asked from this chapter. Check JEE Main Chemistry Syllabus
Questions can be asked from important sub topics such as general trends in physical and chemical properties of elements and compounds like Boron, Silicon, Nitrogen, Phosphorus, Sulphur, and Halogens.
On a general note, elements that have a position within group 13 (group IIIA) to group 17 (group VIIA) of the periodic table along with group 18 which is the zero group elements form the p-Block of the periodic table together.
In this article, you will find the necessary notes to ace p-Block elements.
The last electron enters the furthest p orbital in the p-block elements. In the periphery shell, they have 3 to 8 electrons. As we know that the quantity of p orbitals is three, the most drastic number of electrons that can be compelled in a p orbital structure is six. Resultantly, the periodic table numbered from 13 to 18 shows six groups of p-block elements.
First group: group IIIA known as Boron group
Second group: group IVA known as Carbon group.
Third group: group VA known as Nitrogen group.
Fourth group: group VIA known as Chalcogens.
Fifth group: group VIIA known as Halogens.
Sixth group: zero group or group 18 known as Inert or Noble gasses group.
All three kinds of elements - the Metals, Non-Metals, and Metalloids, are available in the p-block. The crisscross path in the p-block isolates each of the elements that are metals from nonmetals. Metals are to be found on the left of the line, and those on the right are non-metals. We uncover the metalloids along the line. Due to the proximity of a wide range of elements, the p-block shows a lot of variety in properties.
Members: B, Al, Ga, In & Tl
Melting Point: Decreases from B to Ga and then increases up to Tl.
Ionization Energies: 1st <<< 2nd < 3rd
Metallic Character: Increases from B to Tl. B is non-metal
Preparation of Boron
From Boric Acid: B2O3(s) + 3Mg(s) → 2B(s) +3 MgO(s)
From Boron Trichloride
(at 1270 k): 2BCl3+ 3H2 (g) → 2B(s) + 6HCl (g)
(at 900 0C): 2BCl3(g) + 3Zn (s) → 2B(s) + 3 ZnCl2 (s)
By electrolysis of fused mixture of boric anhydride (B2O3) and magnesium oxide (MgO) & Magnesium fluoride at 1100 0C
2 MgO- → 2Mg + O2(g)
B2O3 + 3Mg → 2B + 3MgO
By thermal decomposition of Boron hydrides & halides:
B2H6 (g) + Δ → 2B(s) + 3H2 (g)
Preparation of Orthoboric acid
From borax : Na2B4O7 + H2SO4 + 5H2O → Na2SO4 + 4H3BO3
From colemanite : Ca2B6O11 + 2SO2 + 11H2O → 2Ca(HSO3)2 + 6H3BO3
Properties of Orthoboric acid
Action of Heat
Weak monobasic acidic behavior
B(OH)3 ↔ H3BO3 ↔ H+ + H2O +
Thus, in titration with NaOH, it gives sodium metaborate salt.
H3BO3 + NaOH ↔ NaBO2 + 2H2O
Reaction with Metal Oxide
Reaction with Ammonium boron fluoride
Preparation from Boric Acid
4H3BO3 + Na2CO3 --> Na2B4O7 + 6H2O + CO2
Properties of Borax
The aqueous solution of borax is alkaline in nature because of its hydrolysis
Na2B4O7 + 3H2O → NaBO2 + 3H3BO3
NaBO2 + 2H2O → NaOH + H3BO3
Preparation of Diborane
Reduction of Boron Trifluoride
BF3 + 3LiAlH4 → 2B2H6 + 3 LiAl F4
2NaBH4 + H2SO4 → B2H6 + 2H2 + Na2SO4
2NaBH4 + H3PO4 → B2H6 + 2H2 + NaH2PO4
Properties of Diborane
Reaction with water: B2H6 + H2O -->2H3BO3 + 6H2
Combustion: B2H6 +2O2 --? B2O3 + 3H2O ΔH = -2615 kJ/mol
2Al(OH)3 +Heat → Al2O3 + 2H2O
2Al(SO4)3 +Heat → Al2O3 + 2SO3
(NH4)2Al2(SO4)3·24H2O --> 2NH3 +Al2O3 + 4SO3 + 25 H2O
2. Aluminum Chloride AlCl3
Properties of Aluminium Chloride
White, hygroscopic solid
Sublimes at 183 0C
Forms addition compounds with NH3, PH3, COCl2 etc.
Hydrolysis: AlCl3 + 3H2O --> Al(OH)3 + 3HCl + 3H2O
Action of Heat: 2AlCl3 .6H2O --> 2Al(OH)3 à Al2O3+ 6HCl + 3H2O
Elements: C, Si, Ge, Sn, & Pb
Ionization Energies: Decreases from C to Sn and then increases up to Pb.
Metallic Character: C and Si are nonmetals, Ge is a metalloid, and Sn and Pb are metals.
Catenation: C and Si display a tendency to bond with its own atoms to form long chain polymers.
Preparation of Carbon Monoxide
By heating carbon in limited supply of oxygen: C + 1/2O2 --> CO.
By heating oxides of heavy metals e.g. iron, zinc etc with carbon.
Fe2O3 + 3C → 2Fe + 3CO
ZnO + C → Zn + CO
By passing steam over hot coke: C + H2O → CO + H2 (water gas)
By passing air over hot coke: 2C + O2 + 4N2 → 2CO + 4N2 (Producer gas)
Properties of Carbon Monoxide
A powerful reducing agent : Fe2O3 + 3CO → 2Fe + 3CO2
CuO + CO → Cu + CO2
Burns in air to give heat and carbon dioxide: CO + 1/2O2 → CO2 + heat.
Tests For Carbon Monoxide
Burns with a blue flame
Changes the filter paper that is soaked in platinum or palladium chloride to pink or green.
Preparation of Carbon di-oxide
By action of acids on carbonates: CaCO3 + 2HCl → CaCl2 + H2O + CO2
By combustion of carbon: C + O2 → CO2
Properties of Carbon di-oxide
Turns lime water milky Ca(OH)2 + CO2 → CaCO3 ¯ + H2O,
Milkiness disappears when CO2 is passed in excess
CaCO3 + H2O + CO2 → Ca(HCO3)2
Solid carbon dioxide or dry ice is availed by cooling CO2 under pressure. It changes from the solid state straight to gaseous state without liquefying (hence dry ice).
Salt like Carbides : Ionic salts containing either C22- (acetylide ion) or C4- (methanide ion)e.g. CaC2, Al4C3, Be2C.
Covalent Carbides : Carbides of non-metals such as silicon and boron. The atoms of two elements are bonded to each other through covalent bonds. SiC also known as Carborundum.
Interstitial Carbides : Formed by transition elements and consist metallic lattices with carbon atoms in the interstices. e.g. tungsten carbide WC, vanadium carbide VC.
Prepared by fusing soda ash with pure sand at high temperature:
Na2CO3+ SiO3 → Na2SiO3 +CO2
Silicon polymers containing Si – O – Si linkages are formed by the hydrolysis of alkyl or aryl substituted chlorosilanes and their subsequent polymerisation.
Salts of silicic acid, H4SiO4 comprised of SiO44- units, having tetrahedral structure formed as a result of sp3hybridization.
Elements: N, P, As, Sb & Bi
Atomic Radii: Increases down the group. Only a small increase is seen from As to Bi.
Oxidation state: -3 to +5. Stability of +3 oxidation state increases down the group.
Ionization energy: Decreases from N to Bi.
Preparation of Nitrogen
3CuO + 2NH3 + Heat --> N2 + Cu + 3H2O
CaOCl2 + 2NH3 + Heat --> CaCl2+ 3H2O + N2
NH4NO2 +Heat --> 3H2O + N2 +Cr2O3
Properties of Dinitrogen
Formation of Nitrides (with Li, Mg, Ca & Al): Ca + N2 +Heat → Ca3N2
Oxidation: N2 + O2 → 2NO
Reaction with carbide (at 1273 K): CaC2 + N2 → CaCN2 + C
Oxides of Nitrogen
Oxy -Acids of Nitrogen
|Oxy Acids||Name of oxy – acid|
|Per nitric acid|
Preparation of Ammonia
By heating an ammonium salt with a strong alkali ;NH4Cl + NaOH --> NH3 + NaCl + H2O
Properties of Ammonia
Basic nature : Its aqueous solution is basic in nature and turns red litmus blue.
NH3 + H2O ↔ NH4+ + OH-
Precipitation of heavy metal ions from the aq. solution of their salts:
FeCl3 + 3NH4OH → Fe(OH)3 + 3NH4Cl
AlCl3 + 3NH4OH → Al(OH)3 + 3NH4Cl
CrCl3 + 3NH4OH → Cr(OH)3 + 3NH4Cl
Allotropy of Phosphorus
a) White phosphorus
Translucent white waxy solid
b) Red Phosphorus
Formed by heating white phosphorus in the absence of air.
Does not burn spontaneously at room temperature.
c) Black Phosphorus: Formed by extra heating of red phosphorus.
Formation of Phosphonium Iodide: PH3 + HI à PH4I
Combustion: PH3 + 2O2 à H3PO4
P4+ 6Cl2 → 4PCl3
PCl3 + 3H2O → H3PO3 + 3HCl
PCl5 + 4H2O → POCl3 à H3PO4 +5HCl
PCl3 + 3CH3COOH → 3 CH3COCl +H3PO3
PCl5 + CH3COOH → CH3COCl + POCl3+ HCl
2Ag + PCl5 → 2AgCl + PCl3
2Sn + PCl5 → SnCl4 + 2PCl3
PCl5 + Heat → PCl3 + Cl2
|2.||Common oxidation state||-2||-2, +4, +6||+4, +6||+4, +6|
|3.||Atomic radius (pm)||66||104||116||143||167|
|4.||First ionization energy (KJ/mol)||1314||1000||941||869||812|
Formation of volatile Hydrides
Formation of Halides
a) All the elements (except Se) form monoxide.
b) All the elements form dioxide with formula MO2. SO2 is a gas, SeO2 is volatile solid, while TeO2 and PoO2 are non – volatile crystalline solids.
c) Ozone: It is unstable and easily reduces into oxygen. It behaves like a strong oxidising agent due to the ease with which it can liberate nascent oxygen.
|Sulphurous acid H2SO3. Sulphuric acid H2SO4 Peroxomonosulphuric acid H2SO5(Caro’s acid) Peroxodisulphuric acid H2S2O8 (Marshell’s acid) Thio sulphuric acid H2S2O3 Dithiconic acid H2S2O6 Pyrosulphuric acid H2S2O7||Selenious acid H2SeO3 Selnenic acid H2SeO4||Tellurous acid H2TeO3. Telluric acid H2TeO4.|
1. Rhombic sulphur
It has a bright yellow colour.
It is insoluble in water and carbon disulphide. Its density is 2.07 gm cm-3 and exists as S8 molecules. The 8 sulphur atoms in the S8 molecule form a puckered ring.
2. Monoclinic Sulphur
Stable only above 369 K. It is a dull yellow coloured solid, also known as b - sulphur. It is soluble in CS2 but insoluble in H2O.
It gradually changes into rhombic sulphur. It also exists as S8 molecules which possess a puckered ring structure. It differs from the rhombic sulphur in the symmetry of the crystals.
3. Plastic Sulphur
It is obtained by pouring molten sulphur to cold water.
It is an amorphous form of sulphur.
It is insoluble in water as well as CS2.
Due to its strong affinity for water, H2SO4 acts as a powerful dehydrating agent.
Concentrated H2SO4 reacts with sugar, wood, and paper to form black mass of carbon. This phenomenon is called charring.
It is a moderately strong oxidizing agent.
Decomposes carbonates, bicarbonates, sulphides, sulphites, thiosulphates and nitrites at room temperatures.
Salts like chlorides, fluorides, nitrates, acetates, oxalates are decomposed by hot conc. H2SO4 liberating their corresponding acids.
|Type XX’1 (n = 1) (with linear shape)||Type XX’3 (n = 3) (with T-shape)||XX’5 (n = 5) (with square pyramidal shape)||XX’7 (n = 7) (with pentagonal bipyramidal shape)|
|ICl, IBr, IF||ICl3, IF3||IF5||IF7|
Properties of Hydrogen Halides
· All the three acids are reducing agents. HCl is not attacked by H2SO4.
2HBr + H2SO4 → 2H2O + SO2 + Br2
2HI + H2SO4 → 2H2O + SO2 + I2
All the three react with KMnO4 and K2Cr2O7
2KMnO4 + 16HCl → 2KCl + 2MnCl2 + 8H2O + 5Cl2
K2Cr2O7 + 14HBr → 2KBr + 2CrBr3 + 7H2O + 3Br2
Other reactions are similar.
Dipole moment : HI < HBr < HCl < HF
Bond length: HF < HCl < HBr < HI
Bond strength: HI < HBr < HCl < HF
Thermal stability: HI < HBr < HCl < HF
Acid strength: HF < HCl < HBr < BI
o Reducing power: HF < HCl < HBr < HI
Ions that have two or more atoms of which at least one is nitrogen and have properties like those of halide ions are known as pseudohalide ions. A few of these pseudohalide ions could get oxidised to form covalent dimers comparable to halogens (X2). Such covalent dimers of pseudohalide ions are known as pseudohalogens.
The best known pseudohalide ion is CN–
· (CN)2 cyanogen
· (SCM)2 thiocyanogen
Important stable compounds of Xenon
XeOF4 Square pyramidal
XeO2F2 Distorted octahedral
Did you know?
The first rare gas compound was discovered by Bartlett and was known as Xe+ (PtF6]–.
Acidic Character: Acidic character of halogens increases with the increase in oxidation number of the halogen: HClO4 > HClO3> HClO2 > HOCl
· Ca(OCl)2 + 2HNO3 → Ca(NO3)2 + 2HOCl
· BaO2 + 2ClO2 → Ba(ClO2)2 (liquid) + O2
· Ba(ClO2)2 + H2SO4(dil.) → BaSO4 ¯ + 2HClO2
· 6Ba(OH)2 + 6Cl2 → 5BaCl2 + Ba(ClO3)2 + 6H2O
· Ba(ClO3)2 + H2SO4(dil.) → BaSO4 ¯ + 2HClO3
· KClO4 + H2SO4 → KHSO4 + HClO4
· 3HClO3 → HClO4 + 2ClO2 + H2O
The noble gases are inert. They do not take part in the reactions easily because they have -
stable electronic configuration (a complete octet).
high ionization energies.
low electron affinity.
Practice with JEE Main Question Paper
|Molecule||Total electron pairs (BP + LP)||Hybridisation||Shape|
Uses of Nobles Gasses
Filling airships and observation balloons.
Oxygen mixture of deep sea divers.
Treatment of asthma.
Inflating aeroplane tyres.
Providing inert atmosphere in melting and welding of easily oxidizable metals.
Filling discharge tubes, that have different characteristic colours and are used for advertising purposes.
Beacon lights for safety of air navigators as the light contains fog and steam perpetrating power.
In addition to nitrogen, it is used in gas–filled electric lamps as it is more inert than nitrogen.
1. Electronic Configuration
The usual electronic design of p-block components for the valence shell is ns 2 np1-6 (except He). The internal core of the electronic structure could however contrast.
The general electronic structure displayed by p-block group 13 to 18 elements is is displayed below -
Helium 's standard electronic configuration is 1s2. Owing to their unique electronic structure, p-block elements show a great range of properties.
2. Metallic Character
As previously mentioned, p-block includes a broad variety of elements including metals, non-metals, and metalloids. The p-block is the largest locale of the periodic table comprising metalloids. The non-metallic character falls down the group while in the p-block there is a steady change in non-metallic character from left to right. The metallic character continues to increase down each group as it reduces as we pass over a period from left to right. Evidently, the heaviest element in a p-Block group is the most metallic in nature.
3. Atomic Density
The Atomic Density of elements in p-block increases down the group, which is due to the change in the size of the atom down the chain. Although it decreases as we pass over the period from left to right, this is due to the reduction in the nuclear size of all elements in the p-block over the period. Aluminum has a low density of the significant number of elements, and is commonly used as a building material.
4. Melting and Boiling Points
The melting and boiling points increase in the group gradually given that the atomic mass increases down the group and hence the intermolecular forces rise as well. On the other hand, due to greater intermolecular forces (van der Waals interaction), the melting point of group 17 and 18 rises down the group.
5. Oxidation State
The p-block elements exhibit a variable state of oxidation. Within the periodic table, the oxidation shows increments as we pass from left to right. The greatest state of oxidation that a p-block element has is equivalent to the aggregate number of valence electrons. As shown, the oxidation states found in different classes are as follows -
In any case , given such p-block elements, there might also be other oxidation states that usually vary by a unit of two from an aggregate number of valence electrons. The other two units of oxidation state, not exactly the group oxidation state that appeared by different groups, are as follows -
The relative inertia of these two oxidation states , the group oxidation state and the other oxidation state, two units less than the group oxidation state, may change from group to group in any case.
6. Atomic and Ionic Radii
As we pass down the p-block group, one additional shell is included in the following element compared to the previous one. This eventually increases the nuclear and ionic radius of every next element down the group, showing that the nuclear and ionic radii are increasing down the group. Over the period, the trend is not the same. When we pass in a period to the right, the Atomic radii and the Ionic radii of p-block elements are decreasing. Atomic radius from Boron to Aluminium increases tremendously. This expansion is due to the more prominent effect of filtering produced by the eight electrons shown in the penultimate shell.
7. Electrode Potential
The p-block elements have a positive anode potential, by and large. It reduces the down the groups for the most part.
For example, consider the following halogen-group anode possibilities -
We can say from the scientific data above that the anode potential in the p-block is decreasing down the groups.
8. Ionization Energies
The p-block elements give strong ionization possibilities. Because of the efficient expansion of atomic charge, the ionization energies of p-block elements increase towards the right in a period. The ionization energy values decrease down the group as shown by the general trends and do not decrease smoothly. Ionizing Non-metal energies are greater than metals. It is most intense for a noble gas, as the structure of noble gasses is fully filled. Some elements at the base of the group such as Iron, Silver, Thallium, Bismuth, and so on behave more as a metal of weak ionizing energies.
9. Magnetic Properties
The p block elements Radon, Astatine, Iodine, and Polonium in nature are Non-Magnetic. Tin is Paramagnetic, and the other p-block elements are Diamagnetic in nature.
10. Complex Formation
The small size and the more noticeable charge of the elements of different p-block groups empower them to have a more influential propensity to form complexes compared with the s-block elements. This complex formation propensity diminishes down the group as the size of the atoms increases down the group.
11. Chemical Reactivity
The Chemical Reactivity of elements in p-block increases as we pass in a period to the right. The chemical reactivity of the elements decreases down the group as we step down within a group.
All of the noble gasses' orbitals are fully packed with electrons, so it is extremely difficult to crack their stability in any manner, whether it be the elimination of electrons or the insertion of electrons. Therefore, the noble gasses exhibit poor compound reactivity. Considering their low reactivity, noble gasses are used routinely in welding, for example, where a non-reactive atmosphere is needed. There are two chemically important groups of non-metals going up before the noble gas family. These are halogens (Group 17) and chalcogens (Group 16). Such two groups of elements have high enthalpies of electron gain which can provide one or two electrons framing an anion promptly or obtain the stable noble gas structure suggesting great chemical reactivity in this manner.
A) All halogens are typically present in a combined form.
B) Fluorine responds rapidly to every material that interacts with it.
C) Chlorine, bromine, and iodine are dynamically less reactive while at the same time, frame compounds with a variety of elements, particularly metals.
D) Halogens are always solid oxidizing agents. The halogens oxidize different compounds, and reduce themselves.
E) All halogens bind directly to frame sodium halides with sodium.
F) All halogens bond to form phosphorus halides with red phosphorus.
G) Halogens immediately react with salt-forming alkali metals.
H) The presence of chlorine, bromine, and iodine may be detected by acidified silver nitrate solution.
A) As we reach the right side of the periodic table, the parallels between the elements within the group become evidently more notable. It refers to category VIA, except for polonium which is not included due to its radioactivity.
B) The entities in the VIA form X2 – particles when reacting with extremely electropositive metals.
C) The tendency to decrease to the -2 oxidation is greatly decreased as we move down.
D) Oxygen is a gas at normal pressure and temperature. This occurs in all allotropic structures: O2, which accounts for 21 per cent of the world's air, or O3 (ozone), which slowly decreases to O2.
E) The ozone itself ingests long-wavelength ultraviolet radiation, preventing these toxic rays from touching the surface of the earth, which in some manner or another will increase the risk in malignancy of the human skin and may even contribute to other environmental issues.
F) Selenium and tellurium compounds are of limited commercial interest because they are toxic.
A) The organic reactivity of the metalloids depends on the reactive element. For example, Boron behaves as a non-metal when reacting with sodium, but when reacting with fluorine it goes on like a metal.
B) Hence, we can conclude from the above example that metalloids exhibit varying chemical properties.
C) They act as non-metals when metals react and they act like metals when non-metals react.
D) They are normally oxidized in reactions due to their low electronegativity. The metalloid oxides are usually amphoteric.
A) All group VA elements form trihydrates after reaction with hydrogen.
B) The reactivity weakens down the group.
C) The elements in group VA either frame trioxides or pentoxides when oxygen reacts.
D) Often, when reacting with halogens, they form trihalides or pentahalides.
E) All of the group VA elements form binary compounds by reacting with metals.
F) Nitrogen and phosphorus compounds are the most essential compounds of group VA elements.
G) Nitrogen and phosphorus are most widely used as manure.
A) Unlike groups IA and IIA, none of group IIIA elements directly form hydrides when reacting with hydrogen.
B) All group IIIA elements also correspond to form trihalides when reacting with halogens, rather than simply forming halides like group IA and group IIA.
A) Carbon is capable of forming strong bonds with other carbon molecules and frames a wide array of organic compounds along those lines.
B) In the +4 oxidation state, the lead functions as a solid oxidizing agent, increasing two electrons and reducing it to +2 oxidation state after taking up electrons.
C) Lead forms covalent compounds and bonds strongly to carbon in the +4 oxidation state.
D) In addition to the metals, certain tin and lead mixes are of market importance themselves. To repress dental concerns, for example, Tin (II) fluoride (stannous fluoride) is applied to a particular toothpaste.
E) Lead is also used in two business applications. One, the lead-acid storage batteries used to power autos, and the other is in the fuel for vehicles.
In p-block, the conductivity of elements increases down the group. The metals present in the p-block are good electricity and heat conductors whilst the non-metals are poor electricity and heat conduits. In the middle of the metals and nonmetals lies the conductivity of metalloids.
Group IIIA elements
All of the elements are silvery solids except boron that is brown solid.
Group IVA elements
Color of group 16 elements: