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Gallium Ga (Element 31) of Periodic Table

Gallium Ga (Element 31) of Periodic Table

31 Ga (Gallium)  
Solid gallium is a blue-gray metal, and Highly pure metal has a beautiful silvery appearance. 
It is soft enough to be cut with a knife.
It is one of four metals (mercury, cesium, and rubidium), which can be liquid near room temperature, has one of the longest liquid ranges of any metal.

AGallium is stable in air and water, but it reacts with and dissolves in acids and alkalis.
The metal expands 3.1 % on solidifying; So, it should not be stored in glass or metal containers, because they may break as the metal solidifies.

gallium element

Gallium Melt on Hand

Identity
CAS Number: CAS7440-55-3
CID Number:  CID5360835                                         
DOT Hazard Class:  8
DOT Number:  2803
RTECS Number:  RTECSLW8600000

Basic Properties of Gallium

Pronunciation:  Gal-ee-am
Appearance:  Silvery blue
Mass Number:  70
Standard Atomic weight: 69.723  g/mol
Atomic number (Z):  31
Electrons: 31
Protons:  31
Neutrons:  39
Period:  4
Group:  13
Block:  p
Element category:  Post-transition metal
Electrons per shell:  K2, L8, M18, N3
Electron configuration:  1s22s22p63s23p63d104s24p1

Gallium electron configuration

Gallium Electron Configuration

Thermal Properties of Gallium

Phase:  Solid
Melting point:  302.91 K (29.76 oC, 85.57 oF)
Boiling point:   2673 K (2400 oC, 4352 oF)
Debye temperature:  240 K (-33.15 oC, -27.67 oF)
Fusion heat:  5.59 kJ/mol
Vaporization heat:  256 kJ/mol
Specific heat:  371 J/(kg K)
Molar heat capacity:  29.54 J/(mol.K)
Thermal expansion:  18 μm/(m∙K)
Thermal conductivity:  40.6 W/(m∙K)

Electrical properties of Gallium

Electrical conductivity: 7.1×106 S/m
A Electrical resistivity:  270 nΩ∙m
A Electrical type:  Conductor
Critical point (Superconducting point):   1.083 K (-272.07 oC, -457.73 oF)

Magnetic Properties of Gallium

A Magnetic type:  Diamagnetic
Magnetic susceptibility (xmol):  -21.6×10-6 cm3/mol
Volume magnetic susceptibility:  -0.0000177
Mass magnetic susceptibility:  -3×10-9 m3/kg
Molar magnetic susceptibility:  -0.209×10-9 m3/mol

Physical Properties of Gallium

Density:  5.91 g/cm3 (In solid)  6.095 g/cm3 (In Liquid)
Molar volume:  0.000011809 m3/mol
Young’s modulus:   9.8 GPa
Mohs Hardness:  1.5
Bulk modulus:  GPa
Poisson ratio:  0.47
Brinell hardness:   56.8-68.7 MPa
Sound Speed:  2740 m/s

Atomic Properties of Gallium

Oxidation states:  3,2, 1, -1, -2, -4, -5
Valence Electrons:  4s2 4p1
Ion charge:  Ga3+
The ionization potential of an atom:  5.97
Ionization energies:  1st: 578.8 kJ.mol 2nd: 1979.3 kJ/mol 3rd: 2963 kJ/mol
Ionic radius:   62 pm
Atomic radius:   empirical: 135 pm
Van der Waals:  187 Pm
Covalent radius:  122±3 pm
Filling Orbital:  4p1
Crystal structure:  Orthorhombic
Lattice angles:  π/2, π/2, π/2
Lattice constant:  451.97, 765.8, 452.6 pm
Grid parameters:  a=4.519 Å b= 7.658 Å c=4.526 Å
Space Group Name:  Cmca
Space Group Number:  64

Orthorhombic

Orthorhombic

Reactivity of Gallium

Electronegativity:  pauling scale: 1.81
Valence:  +3
Electron affinity:  28.9 kJ/mol

Nuclear Properties of Gallium

Half Life:  Stable (Infinity) 
Lifetime:  Stable (Infinity)
Quantum Number:  2P1/2
Neutron cross section (Brans):  2.9
Neutron Mass Absorption:  0.0015
Isotopes:   66Ga 67Ga 68Ge 69Ge 70Ge 71Ge 72Ge 73Ge

Isotope Abundance (%) Atomic Mass g/mol Half Life (t1/2)
66Ga Syn 9.5 h
67Ge Syn 3.3 d
68Ge Syn 1.2 h
69Ge 60.11 68.926 Stable
70Ga Syn 21 min
71Ge 39.89 70.925 Stable
72Ge Syn 14.1 h
73Ge Syn 4.9 h

Chemical Reactions of Gallium

AGallium reacts with sulfur forming gallium sulfide:
16 Ga (s) + 3 S8 (s) → 8 Ga2S3 (s)

Reaction of gallium  tri-hydroxide (Ga(OH)3) with hydrogen sulfide (H 2S) at 747 °C, forming Gallium (III) sulfide:
2 Ga(OH)3 + 3 H2S → Ga2S3 + 6 H2O

React with ammonia at 1050 oC, and form Gallium nitride (GaN):
Li3Ga + N2 → Li3GaN2
Similarly  It forms Gallium phosphide (GaP), Gallium arsenide (GaAs), and Gallium antimonide (GaSb).
These compounds have important semiconducting properties.

When heated to a high temperature, gallium(III) halides react with elemental gallium, and form gallium (I) halides:
2 Ga + GaCl3 ⇌ 3 GaCl (g)

Gallium History

Naming:  After Gallia (Latin: France), Homeland of the discoverer
Prediction: Dmitri Mendeleev (1871)
Discovery:  Lecoq de Boisbaudran (French chemist) (1875)

Gallium Uses

Because of high boiling point, It is used in some high temperature thermometers.

AGallium readily alloys with most metals, and has been used as a component in low-melting alloys.
The plutonium pits of nuclear weapons employ an alloy with agallium to stabilize the allotropes of plutonium.

Liquid gallium on porcelain and glass surfaces, forms a brilliant mirror when it painted or coated on glass.
Because of highly reflective, It is also called a liquid mirror.
But due to low melting point It melts near room temperature, so cannot used in mirror.

Gallium arsenide  has a similar structure to silicon and is useful as a substitute of silicon for the electronics industry.
It is capable of converting electricity directly into coherent light and is used in red LEDs (light emitting diodes) and watches.
Solar panels on the Mars Exploration Rover contained gallium arsenide.

Gallium nitride is also a semiconductor, that properties make it very versatile.
It has mainly used in Blu-ray technology, mobile phones, blue and green LEDs, and pressure sensors for touch switches.

Gallium arsenide

Gallium Arsenide Crystal

Gallium nitride

Gallium Nitride Crystal

Biological role:  It has Non-toxicity.

Abundance of Gallium

AGallium is often present in trace amounts in the minerals diaspore (AlO(OH)), germanite, sphalerite, bauxite and coal.
Some flue dusts from burning coal have been shown to contain 1.5% gallium.

It is mainly produced as a by-product of zinc refining.
The Metal is obtained by electrolysis of a solution of gallium(III) hydroxide in potassium hydroxide.

Annual world wide production is around 395 tons.
10×10-7% (In Universe)
76×10-5% (In Meteorites)
4×10-6% (In Sun)
0.0019% (In Earth’s Crust)
3×10-9% (In Oceans)

Diaspore mineral

Diaspore Mineral

Germanite mineral

Germanite Mineral

sphalerite

Sphalerite (Black) with Galena (Gray) & Chalcopyrite (Golden) Ores

Bauxite mineral

Bauxite Mineral

Coal

Coal Ore

World’s Top 3 producers of Gallium

1) China
2) Germany
3) Kazakhstan

#Gallium

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