CLASS 11 chemistry ch 11

Class 11 chemistry chapter 11

Chapter 11 The p- Block Element

The p- Block Element

Chapter 11 The p- Block Element

The p- Block Element

Elements in which the last electron enters in the any one of the three p- orbital of their outermost shells – p-block elements

• Gen. electronic configuration of outer shell is ns2np1-6 The inner core of e-config.may differ which greatly influences their physical & to some extent chemical properties.

• The block of elements in the periodic table consisting of the main groups :

• Group13

(B to Tl)

• Group14 (C to Pb)

• Group15 (N to Bi)

• Group 16 (O to Po)

• Group17 (F to At)

• Group18 (He to Rn)

(1) Members at the top and on the right of the p-block are nonmetals (C, N, P, O, F, S, Cl, Br, I, At).

(2) Those on the left and at the bottom are metals (Al, Ga, In,Tl, Sn, Pb, Sb Bi, Po).

(3) Between the two, from the top left to bottom right, lie an ill-defined group of metalloid elements (B, Si, Ge, As, Te)

GROUP 13 : The boron group

• Outer Electronic Configuration:-ns2np1

• group members: boron (B), aluminum (Al), gallium (Ga), indium (In) & thallium (Tl) . All, except boron, are metals.

• Boron show diagonal relationship with Silicon; both are semiconductors metalloids & forms covalent compounds.

• Boron compounds are electron deficient, they are lack of an octet of electrons about the B atom .

• diborane B2H6 is simplest boron hydride

• Structure: three-center two-electron: the H atoms are simultaneously bonded to two B atoms the B-H bridging bond lengths are greater than B-H terminal.

• - Boron oxide is acidic (it reacts readily with water to form boric acid)

• aluminium compounds:aluminium oxide is amphoteric

• aluminum halides, e.g., AlCl3 is dimer, an important catalyst in organic chemistry have anincomplete octet, acts as Lewic acid by accepting lone pairs from Lewic bases, forming adduct

• aluminum hydride, e.g., LiAlH4, a reducing agent

• Atomic Properties - Electronic Configurations

Element

Symbol

Atomic

No.

Electronic

Configuration

Abundance in Earth’s

Crest (in ppm)

Boron

[He]2s2 2p1

Aluminium

[Ne]3s2 3p1

81,300

Galium

[Ar]3d104s2 4p1

Indium

[Kr] 4d105s2 5p1

Thallium

[Xe] 5d106s2 6p1

0.3

Atomic and ionic radii

• The atomic and ionic radii of group 13 elements are compared to corresponding elements of group 2. From left to right in the period, the magnitude of nuclear charge increases but the electrons are added to, the same shell. These electrons do not screen each other, therefore, the electrons experience greater nuclear charge.

• In other words, effective nuclear charge increases and thus, size decreases. Therefore, the elements of this group have smaller size than the corresponding elements of second group.

• On moving down the group both atomic and ionic radii are expected to increase due to the addition of new shells. However, the observed atomic radius of Al (143 pm) is slightly more than that of Ga (l35 pm).

Ionization energies

Ionization energies for thirteenth group elements are lower than for corresponding members in alkaline countries.

The sharp drop in I.E. B to Al due to increased volume. In the case of Jay, there are ten D electrons in its internal electronic structure.

The very high value of thallium III I. indicates that +3 O.N. The condition is not stable, but 1 is more stable for thallium.

Electrical (or mineral) nature

The elements of group 13 are less electrical motive than the elements of group 2, and as the group descends, the electrical (metallic) nature increases with the decrease of ionization energy. For example, boron is non-metallic white, and other elements are typical minerals.

Oxidation:

The total oxidation state of the thirteenth elements is +3 և + l. +1 The stability of the oxidation state in Al <Ga <In <Tl sequence increases due to the effect of the passive pair.

item:

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Introduction:

Hill

Oxidation state:

+3:

+3, +1:

+3, +1

+3, +1:

The chemical reaction of the elements Gr.13

All components of their compounds show oxidation status + 3: +1. Hydrate:

None of the thirteen groups interact directly with hydrogen. but not.

Hydrate these elements in indirect ways. Boron hydrate is called borax and is classified into two series. A) BnHn + 4, called nidoborans (b) BnHn + 6, called arachnoboranes

Security protection.

2BF3 (g) + 6LiH (s) → B2H6 (g) + 6LiF (s)

Laboratory method

(I) By reacting iodine with a highly soluble sodium borohydride solvent. 2NaBH4 + I2 → B2H6 + 2NaI + H2:

(Ii) Lower BCA3 to LiAlH4 4BCl3 + 3LiAlH4 → 2 B2H6 + 3AlCl3 + 3 LiCl

Diboran structure, B2H6

Some important properties of boronone.

I) Bottom boilers are colorless gases, and the higher boilers are volatile liquids or solids.

2) They undergo spontaneous combustion in air due to the strong boron heat of oxygen. B 2H6 + 3O2 B2O3 + 3H2O + thermostat:

3) Boran interacts with alkali metal hydrates in food esters to form borhydride complexes. B2H6 + 2MH → 2M + [BH4] - (M = Li or Na) metallic borohydride

(4) Diboran interacts with ammonia to form borazine at 450 K. B2H6 + 6NH3 → 3B3N3H6 + 12H2.

Borazin contains a cyclic structure similar to gasoline and called inorganic gasoline.

Other elements of this group are just a few stable hydrates. The stability of the thermal wind decreases when we go into the group.

• AlH3 is a colorless solid polymerization formulated with Al-H-Al bridges. These hydrates are weak in Lewis acids and produce powerful components of the Lewis base (B :) to give MH3 (M = Al or Ga) compounds. They also form complex quaternary hydride anions, [MH4]. Best Hydro-Li Quadrate Formula [AlH4]

Oxides and hydroxides

M2O 3 & M (OH) 3:

Haleeds. The structure of boron triglycerides

Aluminum chloride diameter structure

Boron halogen does not form demers because the volume of boron is so small that it cannot coordinate four large halide ions.

Anomalous properties of boron

1. Boron is a weak non-metallic electrical conductor, while aluminum is a good metal and conductor. B is solid, but Al is a soft metal.

2. Boron exists in two forms: crystalline and amorphous. But Al does not exist in different ways.

3. The melting point and the boiling point of the burner is much higher than the Al.

4. Boron only forms covalent compounds, while the al even constitutes some ionic compounds.

5. Boron hydroxides and their oxides are acidic, while aluminum is an oscillator.

6. Boron triglycerides are found as monomers. On the other hand, aluminum halogens are present as a storm.

7. Boron hydrate is very stable, and aluminum reserves are unstable

• Boron and silicon exhibit non-metallic properties. These are not cations. Both are amorphous, like crystal snow.

The transferred oxide (B2O3) և silica A (SiO2) is both acidic and dissolves A

Boron oxide (B2O3) and silic a (SiO2) both are acidic and dissolve in alkali solutions to form borates and silicates respectively. B2O3 + 6NaOH → 2Na2BO3 + 3H2O SiO2 + 2NaOH → Na2SiO3 + H2O

• The chlorides of both B and Si get hydrolyzed by water to boric acid and silicic acid respectively. BCl3 + 3H2O →H3BO3 + 3HCl SiCl4 + 3H2O → H2SiO3 + 4HCl

The hydrides of Boron and Silicon are quite stable. Numerous volatile hydrides are also known which catch fire on exposure to air and are easily hydrolyzed. Both elements are semiconductors.

Behavior in Aqueous Solutions

1 Al, Ga, In and Tl exhibit a well-defined aqueous chemistry in their tripositive states. Species like [M(OH)4]-, [M(H2O)2(OH)4]-, [M(OH2)6]3+ for M = Al, Ga, In, exist in aqueous solution.

2. Al, Ga. In and T1 ions exist as octahedral aqua ions, [M(OH2)6]3 + in aqueous solution and many salts like halides, sulphates, nitrates and perchlorates exist as hydrates.

3. Aluminiumsulphate forms double salts - called alum, having the general formula M2SO4. Al2(SO4)3.12H2O, where M=Na+ or K+. USES OF BORON & ALUMINIUM

• Aluminium is used extensively in industry and everyday life. It forms many useful alloys with Cu. Mn, Mg, Si and Zn. Hence, aluminium and its alloys find use in packaging, utensil making, construction, aerospace and other transportation industries. It is used as a conductor for transmission of electricity. Aluminium is alsoused in the alumino-thermite process for production of chromium and manganese from their ores.

Group 14 Elements:-The Carbon Family

Group 14 includes carbon (C), silicon (Si), germanium (Ge), tin (Sn) and lead (Pb). General electronic configuration of carbon family is ns2np2. Covalent radius:-Covalent radius expected to increase from Cto Si, From Si to Pb small increase is found.

Ionization Enthalpy:-The first ionization enthalpies of group 14 elements are higher than those of the corresponding group 13 elements. Electronegativity:-Group 14 elements are smaller in size as compared to group 13 elements that’s why this group elements are slightly more electronegative than group13

Chemical properties. -

Carbon and silicon mainly indicate oxidation +4. Germanium creates stable compounds in the +4 state, and only a few are in the +2 state.

Tin causes compounds in both oxidation states. In the case of +2, lead compounds are stable, and in the case of +4, strong oxidizing agents.

Exception. -Pb4 և SnF4 is ionic in nature.

With the exception of CCl4, another tetrachloride is readily degraded with water.

Since carbon does not contain d orbitals, it cannot extend its coordinate number by more than 4.

CCl4 + H2O has no response

SiCl4 + 4H2O Si (OH) 4 + 4HCl silicon acid

Carbon properties. - Digital types are effects.

1 diamond

2- Graphite

3- Fullness

Diamond.

Every carbon atom in a diamond is exposed to SP3 hybridization. Each carbon track is connected to four other carbon atoms.

Graphite.

In graphite, hybrid carbon graphite SP2 contains a two-dimensional paper-like structure consisting of a series of hexagonal rings that merge together. The graphite conducts electricity along the plate. It is very soft and slippery. Three scientists participated in the salutation: R.E Smalley, R.F Curl and H.W. Kroto.

We are satisfied.

I made it direct C oxidation with limited oxygen supply. 2C + O2 (g) → 2CO (g) in commercial form by passing the hot steam through the steam.

Satisfy:

It is made from complete combustion of carbon and carbon fuel from excess air. C (s) + O2 (g) → CO2 (g)

Laboratory method.

In the laboratory, it is synthesized by diluCCl on CaCO3 CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + CO2> / (g) + H2O (l) silicone.

dioxide. -

COVALENT silicon dioxide was solid, dimensional.

Each silicon atom is covalently linked to four quadruple oxygen atoms. Silicon. Silicon are synthetic organic-silicon organic polymers having common formulas (R2SiO) n where R = alkyl (methyl, ethyl or vinyl) silicate. The main structure of silicate is SiO44

Zeolite.

Zolites are metallic alumina silicate. Mineral cations involved in the formation of Na +, K + or Ca2 + zeolites are usually used. Ol riolites are used to remove permanent hardness.

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