3. 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
5. 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 conduct
electricity .
The elements of group 3A are
relatively reactive at normal
temperature except boron is
reactive at high temperature .
METALLIC CHARACTER
6. 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
7. 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
8. 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
9. 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
11. Boron is strong oxophiles and It’s oxides is very important like
1- Boron sesquioxides ,B2 O3
(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 salt
And when it reacts with strongly acidic oxide it behaves as a basic
oxide
P2O3+B2O3 2BPO4
REACTION OF BORON WITH OXYGEN
12. 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
13. 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
14. 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 HOH3 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
16. ALUMINIUM has a strong affinity for oxygen and the reaction is
strong exothermic.
2AL+3/2O2 AL2O3
The strong affinity for oxygen is used in the extraction of other
metals from their oxides
8AL+3Mn3O4 4Al2O3+9Mn
2Al+Cr2O3 Al2O3 +2Cr
Gallium , like 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
17. The boron hydride is called boranes like alkanes there’re
almost 20 boranes fall into series:
BORON WITH HYDROGEN (HYDRIDES )
Aracho - BnHn+6Nido - BnHn+4Closo - BnHn
-2
B4H10 tetraboraneB2H6 diboraneCloso - B6H6
-2
B5H11 petaboraneB5H9 pentaboraneCloso - B12H12
-2
B6H10 Hexaborane
B10H14 decaborane
18. 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 )
19. 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 NH3)
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 flash .
B2H6 + 3O2 2B(0H)
BORON WITH HYDROGEN (HYDRIDES )
20. 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 )
25. 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
26. Glass and ceramics
Detergent formulations and bleaching agents
Insecticides
Semiconductors
Magnets
High-hardness and abrasive compounds
Boron carbide
Other super hard boron compounds
Shielding in nuclear reactors
Pharmaceutical and biological applications
Research areas
APPLICATION OF BORON
27. Aluminium chloride (AlCl3) is used in petroleum refining and in the
production of synthetic rubber and polymers. Although it has a
similar name, aluminium chlorohydrate has fewer and very different
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
28. Semiconductors
Biomedical applications
Magnesium gallate containing impurities (such as Mn2+), 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.
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
29. Electronics
Very small amounts used in aluminium alloy sacrificial 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 fill gaps.
Used as a calibration material for Differential 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
30. 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 significantly 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
31. 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
