By : Mahmoud Galal Zidan chemistry Department

GROUP 3A ( 13 )

(P-BLOCK ELEMENTS OF PERIODIC

TABLE)

INDEX

Introduction

Physical propertiesChemical Reactions

Applications

Group 3A or called the boron group comprising :1- Boron (B)2- Aluminum (Al)3- Gallium (Ga)4- Indium (In) 5- Thallium (Tl)6- Ununtrium (Uut)The elements in the boron group are

characterized by having three electrons in their outer energy levels (valence layers).

These elements have also been referred to as earth metals.

INTRODUCTION OF GROUP 3A

PHYSICAL PROPERTIES

Metallic properties

softness

Isotopes and Toxicity

Oxidation state

Abundance

The metallic character increase down group 3A .Boron is metalloid (non-metal) and. Ununtrium has

not yet been confirmed to be a poor metal one or not .

Also they are metals they conduct electricity and heat very well , but boron need a high temperature to conductelectricity .

The elements of group 3A arerelatively reactive at normal temperature except boron is reactive at high temperature .

METALLIC CHARACTER

The hardness decrease down the group and the softness increase down.

All Elements of group 3A is soft except Boron Boron is relatively hard .Ununtrium is the softest element in boron

group but it’s not natural element so the softest element is Thallium .

SOFTNESS

All the elements in group 3A have a stable isotopes .

Boron , Gallium and Thallium has a two stable isotopes .

Aluminium and Indium are a mono isotopes ( they have a one

stable isotope ) .

All compound of group 3A are toxic but some compounds are

toxic for plants , some only toxic for animals and some toxic

for both .

ISOTOPES AND TOXICITY

The tri-oxidation state less stable down group 3A ,but the mono-oxidation state more stable down the group .

fagan's rule: the small size atoms form covalent bonds and the large size ones form ionic bonds .

Boron has only a tri oxidation state.Aluminium always trivalent but rarely univalent and

unstable .Gallium the compounds of a monoxidation (+I) is less

stable than the compounds of (+III) ,there’re not pure Ga (+I) and (+III) .

Indium the compounds of a monoxidation (+I) is less stable than the compounds of (+III) .

Thallium The compound (+I) more stable than (+III) compounds .

OXIDATION STATE

Boron is a relatively rare element in the Earth's crust, representing only 0.001% .

Aluminium occurs widely on earth, and indeed is the third most abundant element in the Earth's crust (8.3%).

Gallium is found in the earth with an abundance of 13 ppm.

Indium is the 61 st most abundant element in the earth's crust,

thallium is found in moderate amounts throughout the planet.

Ununtrium is never found in nature and therefore is termed a synthetic element.

ABUNDANCE

CHEMICAL REACTION

With Oxygen (oxides and Oxo compounds

)

With Hydrogen (Hydrides)

With Halogens (Halides)

With Air

Boron is strong oxophiles and It’s oxides is very important like 1- Boron sesquioxides ,B2O3 (sesquioxides mean 1 and 0.5).

Preparation :- - By heating the element of boron in oxygen 4B+3O2 2B2O3

- By dehydrating the boric acid 2H3BO3 2HBO2 B2O3

Properties :- the unhydride form of ortho boric acid has acidity and metallic oxides properties : B2O3+3MgOMg3(BO3)2

Acid + strong base saltAnd when it reacts with strongly acidic oxide it behaves as a basic oxide P2O3+B2O3 2BPO4

REACTION OF BORON WITH OXYGEN

Structure : (BO3

-3) in boron sesquioxides ( Boric acid B2O3 )

Each boron atom is bonded to three oxygen arranged at the corners of an equilateral triangle .

REACTION OF BORON WITH OXYGEN

Ortho Borates: contains discrete BO3 ions like Mg3(BO3)2

Meta Borates : contains simple unites of BO3 but join in chain or ring (means has a polymeric structure )

REACTION OF BORON WITH OXYGEN

2- Boric acid: It’s a very weak acid in aqueous solution and the complex forms with water is the actual source of protons so it acts as a weak monobasic acid . The solid of orthoboric acid contains triangular HOH 3 units

which are bonded together through hydrogen bond into 2D sheet with hexagonal symmetry .

Orthoboric acid has in liquid state a plane triangular but when soluble in water it donates protons and accept (OH -) B(OH)3 +2H2O B(OH)4 + H3O+

REACTION OF BORON WITH OXYGEN

but at high concentration polymeric meta-borate species are formed .

REACTION OF BORON WITH OXYGEN

ALUMINIUM has a strong affi nity for oxygen and the reaction is strong exothermic.

2AL+3/2O2 AL2O3

The strong affi nity for oxygen is used in the extraction of other metals from their oxides 8AL+3Mn 3O4 4Al2O3+9Mn 2Al+Cr2O3 Al2O3 +2Cr

Gallium , l ike aluminium , forms an amphoteric oxide and hydroxide .

Thallium and Indium sesquioxides are completely basic where thallous hydroxide TlOH is a strong base and soluble in water .

Ununtrium is a radioactive element that never react with oxygen

REACTION OF ALUMINIUM AND OTHER METALS WITH OXYGEN

The boron hydride is called boranes like alkanes there’re almost 20 boranes fall into series:

BORON WITH HYDROGEN (HYDRIDES )

Aracho - BnHn+6 Nido - BnHn+4 Closo - BnHn-2

B4H10 tetraborane

B2H6 diborane Closo - B6H6-2

B5H11 petaborane B5H9 pentaborane

Closo - B12H12-2

B6H10 Hexaborane

B10H14 decaborane

Diborane : is considered the simplest member of boranes .It decomposes very slowly at r.t forming higher boranes .

Preparation 1- Mg3B2 + H3PO4 Mixture of boranes B2O3

2- 2BF3 + 6NaH B2H6 + 6NaF 3- 4BCl3+3Li(AlH4) 2 B2H6 + 3 LiAlCl4

Structure sp3 hybridization

BORON WITH HYDROGEN (HYDRIDES )

Reaction 1- by hydrolysis :

B2H6 + 6H2O 2B(0H)3 + 6H2

2- with ammonia : B2H6 + NH3 B2H6.2NH3 at law temperature (excess of NH3)

B2H6 + NH3 (BN)x at High temperature (excess of NH 3)

B2H6 + NH3 (B3N3) at High temperature (excess of B2H6.2NH3) .

3- with air : Diborane reacts spontaneously with air , often with explosive violence and a green fl ash .B2H6 + 3O2 2B(0H)

BORON WITH HYDROGEN (HYDRIDES )

The hydride of indium and thallium are very unstable .

The hydride of aluminium and gallium is much more limited than that of boron .

Like AlH3 exists as a solid but not available , it available as (AlH3)n .Gallium : (Ga2H6) prepared in 1994 .

Lithium tetrahydroaluminate LiAlH4 and Lithium tetrahydrogallate LiGaH4 are much more hydridic

than [BH4]- due to the high electronegativity of boron compared with Al and Ga , and LiAlH4 is widely used as a reducing agent .

OTHER ELEMENTS OF GROUP 3A WITH HYDROGEN (HYDRIDES )

Mono Halides boron forms a number of stable (BX) ex other elements of group 3A forms monohalides MX containing metals with +1 oxidation state . Where oxidation state (+1) increase in stability down the group .Al(X) not stable in solid state and ( GaX , Inx , TiX are known in solid state . Where TlX is the most stable) .

HALIDES

dihalides Boron Forms di-halides of formula B2X4 , these compounds decompose slowly at r.t .

other elements made a known di halides but not used.

HALIDES

Trihalides : Boron form trihalides at a general formula BX3 where (X = Cl,Br,F) I is formed at up normal condition . they are monomeric in the gas ,liquid and solid state BF 3 and BCl3 are gases and BBr3 is liquid and BI3 is solid. BF3 can readily accept a lone pair of electron from a donor atom like N,O,P,S and Lewis acid . structure of BF3

HALIDES

Trihalides : and when BF3 accept a lone pair of electron from a NH3 or trimethylamine . A tetrahedral molecule is formed .

Of other elements : they forms covalent trihalides with all halides except F because the higher electronegativity it form ionic trihalides and when it dissolve in water the covalent dimmer is broken into and 3X - because of the higher heat of hydration .

HALIDES

Boron : - Pure crystalline B is very unreactive except at high temperature by mixing conc.H2SO4 and conc.HNO3 .

- Impure amorphous ,burns in air to form oxide and nitride . Aluminium : Al is stable at air and water due to heavy

thin layer of oxide on surface of metal which protects the metal further attack .

Gallium and Indium : Ga and In are stable in air and not attacked by water.

Thallium : Tl is little more active and form superoxide in air

WITH AIR

Glass and ceramicsDetergent formulations and bleaching agents InsecticidesSemiconductorsMagnetsHigh-hardness and abrasive compounds

Boron carbideOther super hard boron compounds

Shielding in nuclear reactorsPharmaceutical and biological applications Research areas

APPLICATION OF BORON

Aluminium chloride (AlCl3) is used in petroleum refi ning and in the production of synthetic rubber and polymers. Although it has a similar name, aluminium chlorohydrate has fewer and very diff erent applications.

Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles, etc.) as sheet, tube, castings .

Packaging (cans, foil .) Construction (windows, doors, siding, building wire.) A wide range of household items, from cooking utensils to

baseball bats, watches. Street lighting poles, sailing ship masts, walking poles. Outer shells of consumer electronics, also cases for

equipment e.g. photographic equipment. Electrical transmission lines for power distribution MKM

steel and Alnico magnets Super purity aluminium (SPA, 99.980% to 99.999% Al), used in electronics and CDs.

APPLICATION OF ALUMINIUM

SemiconductorsBiomedical applicationsMagnesium gallate containing impurities (such as Mn 2+),

is beginning to be used in ultraviolet-activated phosphor powder.

As a liquid metal ion source for a focused ion beam In a classic prank, scientists would fashion gallium spoons

and serve tea to unsuspecting guests. The spoons melt in the hot tea. طرقيع

As an additive in glide wax for skiis, and other low friction surface materials. US 5069803, Sugimura, Kentaro; Shoji Hasimoto & Takayuki Ono, "Use of a synthetic resin composition containing gallium particles in the glide surfacing material of skis and other applications", issued 1995

APPLICATION OF GALLIUM

Electronics Very small amounts used in aluminium alloy sacrifi cial anodes

(for salt water applications) to prevent passivation of the aluminium.

To bond gold electrical test leads to superconductors, indium is used as a conducting adhesive and applied under a microscope with precision tweezers.

In the form of a wire it is used as a vacuum seal and a thermal conductor in cryogenics and ultra-high vacuum applications. For example, in manufacturing gaskets which deform to fi ll gaps.

Used as a calibration material for Diff erential scanning calorimetry.

It is an ingredient in the gallium-indium-tin alloy Galinstan, which is liquid at room temperature while not being toxic like mercury.

APPLICATION OF INDIUM

High-temperature superconductivity Medical Electronics Optics: Thallium(I) bromide and thallium(I) iodide crystals

have been used as infrared optical materials, because they are harder than other common infrared optics, and because they have transmission at signifi cantly longer wavelengths. The trade name KRS-5 refers to this material. Thallium(I) oxide has been used to manufacture glasses that have a high index of refraction. Combined with sulfur or selenium and arsenic, thallium has been used in the production of high-density glasses that have low melting points in the range of 125 and 150 °C. These glasses have room temperature properties that are similar to ordinary glasses and are durable, insoluble in water and have unique refractive indices. [

APPLICATION OF THALLIUM

It used in cooling the nuclear reactor as it’s better than CO2 and H2O .

It is an extremely radioactive synthetic element (an element that can be created in a laboratory but is not found in nature); the most stable known isotope, ununtrium-286, has a half-life of 20 seconds.

APPLICATION OF UNUNTRIUM