Beryllium

Beryllium Metal

Beryllium is a chemical element or alkaline-earth metal of Group 2 (IIA) of the periodic table with the symbol Be and atomic number 4. It is used largely in metallurgy to improve the properties of copper and nickel alloys. It is the first member of alkaline earth metals with a very small size and very high effecting nuclear charge. The metal beryllium was discovered from the mineral beryl in 1798 (Vauquelin) but its atomic weight was finalized much later by Mendeleev. It was prepared independently by Wohler and Bussy in 1828 by the reduction of BeCl₃ with potassium.

Properties of Beryllium

It forms a hexagonal closed-packed crystal lattice (HCP). It shows a dipositive oxidation number or state by the liberation or sharing of two valence electrons.

The first ionization energy is rather low than the second ionization energy of the beryllium atom.

Beryllium
Symbol	Be
Discovery	Nicholas Louis Vauquelin in 1797
Name derived from	The Greek word for beryl means beryllo
Common isotope	2Be9
Oxidation states	0, +1, +2
CAS number	7440-41-7
Periodic properties
Atomic number	4
Relative atomic mass	9.012
Electron per cell	2, 2
Electronic Configuration	[He] 2s2
Block	s-block
Group	2
Period	2
Physical properties
State at 20 °C	Solid
Melting point	1287 °C, 2349 °F, 1560 K
Boiling point	2468 °C, 4474 °F, 2741 K
Molar heat capacity	16.443 J mol−1 K−1
Crystal structure	hexagonal close-packed (hcp)
Density	1.85 g/cm3
​Electrical resistivity	36 nΩ m
Atomic properties
Atomic radius (non-bonded)	1.53 Å
Covalent radius	0.99 Å
Electronegativity	1.57 (Pauling scale)
Electron affinity	unknown
Ionization energy (kJ/mol)	1st	2nd	3rd
	899.50	1757.11	14848.77

Beryllium in the Periodic Table

The alkaline earth metal beryllium is placed in period 2 and group 2 of the periodic table. It is an s-block element that lies with magnesium and calcium.

Where is Beryllium found?

The concentration of beryllium is very low (2 to 6 ppm) on the earth’s crust. The small abundance of beryllium is due to the transmutation of the Be atom under the natural bombardment of protons.

The element is readily accessible through the minerals like Beryl (Be₃Al₂Si₆O₁₈) and Phenacite (Be₂SiO₄). It is also found in pegmatite rocks and forms large beautiful crystalline solids that are used as gems like emeralds (green colour) or aquamarine (bluish-green colour).

Production Process

1. The mineral beryl was roasted with sodium fluoride and Na₂SiF₆ at 700 °C to 750 °C to form insoluble Na₃AlF₆ and soluble Na₂BeF₄.
2. The roasted mass is leached with boiling water to form a sodium fluoberyllate solution.
3. The extract is precipitated as Be(OH)₂ by sodium hydroxide at a pH scale of 12.
4. The precipitate reacts with NH₄HF₂ to form ammonium fluoberyllate and is heated at 900°C to form BeF₂.
5. The metal beryllium is produced by the reduction of BeF₂ with magnesium at 1300°C.

Chemical Properties of Beryllium

Beryllium (₄Be⁸) has atomic number 4 and mass number 8. Therefore, Be nucleus contains 4 protons and 4 neutrons surrounded by four electron particles.

All the elements Group-2 like beryllium, magnesium calcium, strontium, barium, and radium are characterized by two valence electrons in the outermost s-shell. These two electrons are always involved together in the formation of chemical bonding in chemistry.

The melting points of alkaline earth metals are considerably higher than that of alkali metals due to the variation of the crystal structure.

We observed that beryllium is much less reactive than the other elements in the group due to its small size. It dissolves in aqueous mineral acids like hydrochloric acid, sulfuric acid, and nitric acid to liberate hydrogen gas.

Interesting Facts About Beryllium

The charge-by-radius ratio for Be⁺² is very high, greater than that of any cations except H⁺ and B⁺³. The closest value is found with Al⁺³. This fact suggests that beryllium and aluminum have similar physical and chemical properties.

• Both the metal dissolves in aqueous alkali by evolving hydrogen.
• The standard electrode potentials of the two metals are equal (−1.7 V).
• The oxides and hydroxides are amphoteric and the anhydrous halides of both metals are formed in dimeric compounds with metal-halogen-metal bridges.
• The thermal stability of both metal sulfates is nearly the same.

Chemical Compounds

Hydrides, Oxides, and Hydroxide of Beryllium

It does not form any hydrides directly but BeH₂ may be obtained by reducing BeCl₂ with lithium hydride with LiAlH₄. Beryllium hydride is an amorphous white solid that decomposes above 250 °C giving hydrogen.

It forms its monoxide (BeO) when heated to oxygen. Beryllium oxide is strongly basic in nature and formed by covalent bonding.

The hydroxide like Be(OH)₂ can be obtained by treating their monoxide with water or by adding alkali to an aqueous solution of the salts.

Carbides, Nitrides, and Halides of Beryllium

The carbide of Be has the chemical formula Be₂C. It is formed by direct reaction with carbon at 1900 °C. It is also obtained by heating metal with acetylene at around 400 °C.

The alkaline earth metal Be burns in nitrogen to form crystalline solid nitrides like Be₃N₂.

All the metals of group 2 combine with halogen at a suitable temperature to form dihalides like BeCl₂ or MgCl₂. All the halides of beryllium are covalent and polymeric in nature. They do not conduct electricity in the molten phase of the metal.

Organometallic Compounds

Beryllium alkyls can be made by a reaction,

HgMe₂ + Be → Hg + BeMe₂ at 110 °C

The aryl compounds of the metal are made by reacting lithium aryl (in a hydrocarbon) with BeCl₂ in ether. These compounds are viscous liquids or solids that are spontaneously flammable in air and rapidly hydrolyzed by a water molecule.

Uses of Beryllium

Beryllium is used widely to improve the properties of transition metals like copper and nickel. About two percent of Be increases the strength of Cu six-fold.

The beryllium alloys are non-magnetic, corrosion-resistant, and possess high strength and good electrical conductance. They find extensive applications in critical moving parts of aerospace or electrical industries like high-speed aircraft, guided missiles, spacecraft, satellites, and nozzles of liquid-fuel rockets

The metal beryllium is also used in nuclear power plants as a moderator and as a window material of electromagnetic spectrum or x-ray tubes.