1. A chemical element, atomic number 2, atomic weight 4.003. (See Appendix 6.) Helium is a chemically inert element that is odorless, tasteless, and noncombustible. Because of its low density it is easily moved through the air passages and therefore requires little effort in breathing on the part of the patient in respiratory distress.
2. Atomic Number 2 Atomic Number 2 is belong to element of Helium. Chemical symbol for Helium is He. Number of protons in Helium is 2.
3. Atomic Number: 2 Symbol: He Atomic Mass: 4 Protons: 2. Atomic Number: 3 Symbol: Li Atomic Mass: 7 Protons: 3.
4. Atomic number 2 is the second most abundant element in the universe, after hydrogen. However, the element is rare on Earth (5.2 ppm by volume in the atmosphere) because nonreactive helium is light enough that it can escape Earth's gravity and be lost to space. Some types of natural gas, such as that from Texas and Kansas, contain helium.

WHAT IS PERIODIC TABLE?

It is a tabular display of chemical elements, arranged in order of atomic number in rows so that elements with similar atomic structure and recurring chemical properties appear in vertical columns. The seven rows of the table are called a periodic table.

In the periodic table, chemical elements are present in rowshorizontally in order of increasing atomic number and vertically according tothe recurring properties of their atoms.

A solid non metal belonging to the third period with atomic number of 15 is phosphorus with symbol P. A metal of valency 1 is potassium with symbol K. Its atomic number is 19 and is an alkali metal. A gaseous element with valency 2 is helium. Its symbol is H e and atomic number is 2. It is an inert gas.

Metals are on the left side and non-metal are on the rightside of the periodic table

GROUPING METHOD

In the periodic table of chemical elements, there is a group (also known as a family) is a column of elements. There are multiple ways of grouping the elements but they are commonly divided into metals, non-metals, metalloids. There are also more specific groups like alkali metals, transition metals, rare metals, alkaline earth, halogens, and noble gases.

The 18 vertical columns of the table are called Groups. Thes-, p- and d-block elements of the periodic table are arranged into these columnsor groups. Each group of elements having the same number of valence electrons. TheSame group elements have similar properties and reactivity. These elements tendto show patterns in atomic radius, ionization energy, and electronegativity.

GROUP 2 OF THE PERIODIC TABLE

Group 2 elements are:

• Beryllium
• Magnesium
• Calcium
• Strontium
• Barium
• Radium

Group 2 elements are called alkaline metals because they formalkaline solutions, hydroxides, when reacting with water and their oxides arefound in the earth’s crust.

ALKALINE METALS

• Theyhave low electron affinity.
• Group1 metals are less reactive than group 2 metals.
• Itsvalence shell contains 2 electrons
• Theyhave low electronegativity
• Compoundsof alkali metals are often insoluble in water
• Alkalinemetals are usually Shiny, silvery.
• Theyhave ions with a +2 charge.
• Theyare solid
• Theyare harder, denser, stronger
• They are found in the earth crust

BERYLLIUM

Occurrence

It is a rare element in-universe. Beryllium was discovered in1798 by French chemist Nicolas-Louis Vauquelin. The name wasderived from the Greek name beryl,‘beryllo’. Friedrich Wohler at berlin in 1828 isolated the beryllium metal.Beryllium generally occurs in the earth’s crust to the extent of 0.0002percent. Beryllium is a steel-gray metal. It is quite brittle. Its chemicalproperties resemble aluminum. Emerald is known to be a variety of beryl.

Physical properties

It has a close-packed hexagonal crystal structure.it has avery high melting point which makes beryllium metal the best heat dissipationcharacteristics per unit weight.it has a low coefficient of linear thermalexpansion. These characteristics make unique stability under thermal loading.In the air, beryllium resists oxidation and corrosion.it is extracted by themineral beryl.

Chemical properties

While bonding with the other atoms, it has a very high ionizationpotential and strong polarization. Beryllium has a +2 oxidation state.it allowsforming many covalent bonds.it dissolves in non- oxidizing acids. Binary compoundsare formed by the combination of beryllium with non-metals such as Berylliumoxide (BeO). It is white solid and has a very high melting point. Emerald andaquamarine contain Beryllium.

Uses

• Itis used to make semiconductor devices.
• Itis useful in making radio equipment and engines.
• Itis used in making windows for X-rays tubes.
• Usefulfor mirrors and camera shutters.
• Itis fabricated into gyroscopes, computer parts, and accelerometers.

MAGNESIUM

Occurrence

It was first isolated in 1808by SirHumphrey Davy by the process of mercury evaporation from the magnesiumamalgam which is made by the electrolyzing a mixture of moist magnesia andmercuric oxide. By heating, mercury was removed from the amalgam and leave themercury metal. He isolated many other alkalies and alkali earth metals.

In June 1808 he described how he obtained magnesium byremoving mercury. He observed that in the air the metal turned into whitepowder and gains weight, reacts with oxygen and returned to its oxide form.

In the earth’s crust, it is the eighth-most abundantelement.it is found in more than 60 minerals.it is found in large deposits ofdolomite, magnesite, brucite, and carnallite and in mineral water wheremagnesium is soluble.

Production of magnesium

The double carbonate of calcium and magnesium, dolomite isfar more widely distributed and seawater provides an inexhaustible source ofthe chloride in the dilute form, while certain concentrated solutions ofmagnesium salts are present in the Dead sea.

There are two methods for the production of magnesium

• Electrolysis ( Dow process )
• Thermalreduction (Pidgeon process )
• Refining

Electrolysis

It consists of two steps

Atomic Number 2 On Periodic Table

• Thepreparation of raw material contains magnesium chloride
• Bythe separation of magnesium chloride into magnesium metal and chlorine gas inelectrolytic cells

MgCl₂ Mg + Cl₂

Magnesium produced on the power consumption of 12 – 18kilowatt-hour per kilogram.in the dehydration process, chlorine can also bereused.

Thermal reduction

In the thermal production of magnesium, the endothermic reactiontakes place. On the high temperature, the reduction of oxides with silicon,frequently ferrosilicon alloy is provided to obtain metal. Carbon is also carriedout in this process

2MgO + Si + 2CaO 2Mg + Ca₂SiO₄

MgO + Ca Mg + CaO

Refining

After extraction, crude magnesium istransported to the shops to remove impurities.

Characteristics and uses

• Magnesiumpowder is an explosive hazard.
• Itis widely used in the manufacturing of mobiles, laptops, cameras and otherelectronic components.
• Ithas good high-temperature mechanical properties and high corrosion resistance.
• Itis used in the manufacturing of aircraft, car engines and missile construction.

CALCIUM

Occurrence

For centuries calcium oxide is used to make plaster andmortar, obtained by heating limestone.in 1808 Humphrey Davy tried to reducemoist lime by electrolysis but he was not successful. Then he tried the mixtureof mercury oxide and lime, this produced an amalgam of calcium and mercury.Then Davy tried using more lime in the mixture and produced more of the amalgamfrom which he distilled off the mercury and leaving just calcium. The wordcalcium derives from the Latin word for lime ‘calx’.

Production of calcium

• Thereaction of calcium chloride with sodium lead alloy
• Bythe electrolysis of molten salt of calcium chloride
• Reductionof calcium compounds by use of Si, Al, Ti, Be

Facts about the calcium

• Calcium is not found free. It the 5^th most abundant element in the earth’s crust. Calcium is also abundant on the Moon.
• Calcium is the most important nutrition for plants and animals. It also exists in the human body, found mainly in bones and teeth.
• Snails and shellfish use calcium in the form of calcium carbonate to build their shells.
• Dairy products and grains are the primary sources of dietary calcium.
• Later the Egypt’s pyramid blocks were built using limestone. The blocks were held together with gypsum and lime-based mortar.

Uses

• Calciumis used in the production process of other metals like uranium and thorium
• Calciumis also used in vacuum tubes.
• Itcan be alloyed with aluminum, copper, lead, magnesium, and beryllium.
• Usedin cement and concrete
• Itis used to remove sulfur, oxygen, and carbon from alloys.
• Itis used in the making of chalks and statues.
• Usedin the making of cheese.

STRONTIUM

Occurrence

It was discovered by the Irish chemist Adair Crawford in 1790.It is found from the lead mine near village Strontian in Scotland. Strontium isthe 15^th most abundant element on the earth’s crust. In 1808 HumphreyDavy isolated the strontium metal, who electrolyzed a mixture of the moisthydroxide or chloride with mercuric oxide, using a cathode oxide and thenevaporated the mercury from the resultant amalgam. Davy built a very largebattery consists of 600 plates from which he passes the electricity throughsalts breaking them down to isolate a new element. He made a paste of magnesiumoxide and strontium sulfate and made a depression in a paste to place mercurymetal as an electrode. Platinum is also used as an electrode at a mercuryelectrode, strontium mercury amalgam is formed when the electricity passesthrough the paste. By heating mercury removed from the amalgam and leave the strontiummetal.

Characteristics

Strontium isotopes are considered non-toxic. Strontium is amixture of 4 stable isotopes. It a silvery metal with a pale yellow tint. It isharder than barium and softer than calcium. When strontium reacts with water itproduces strontium hydroxide and hydrogen gas. It occurs naturally in compoundsand other elements that’s why it has extreme reactivity with oxygen and air.

Uses

• Strontiumis used in the manufacture of color television picture tubes.
• Itis used in the fireworks and signal flares.
• Itscarbonates are used to make a certain type of glass.
• Itplays a great role in biology. Strontium deposited in human bones and attacheson the surface of the bones, it can replace the calcium and lead to the growingproblems.
• Usedin toothpaste to reduce sensitivity
• Itcan increase the risk of cardiovascular problems
• Itis used in refining zinc and also used to produce ceramic magnets.

BARIUM

Occurrence

In 1774, a Swedish chemist Carl Wilhelm Scheele discovered a new base (BaO).In pyrolusite, BaO considered a minor component and he prepared the crystals of barium sulfate from that base. Then he sent the crystals of barium sulfate to John Gottlieb Gahn. After a month, he founded that mineral barite is composed of barium sulfate BaSO_4. In the early 17th century, the crystalline form of barite found near Italy. After heating with charcoal it became an impure barium sulfide. It is an unusual discovery of Bologna stone, nobody suspected that there was a new element to be discovered.

In 1808, for the first time, Sir Humphrey Davy isolated theBarium metal. By electrolysis, he decomposed the barium sulfate. The nameBarium is given from the Greek word Barysmeans heavy. Barium is found 0.045% in the earth’s crust and 13 ug/L inseawater.

Characteristics

Barium is a very reactive metallic element. It resemblescalcium. It is a silvery-white metal. When it cuts, it quickly turns into ablack color due to the formation of barium oxide. Barium is commonly found asbarite and witherite. It has a good conductivity.it is a mixture of 6 stableisotopes. Barium compounds that are soluble having a very poisonous property.

Uses

• Bariumis used in the manufacturing of rubber, vacuum tubes, and pyrotechnics.
• Itis used as a weighting compound in the manufacturing of glass, paints, andpigments.
• Itis used as a deoxidizer in copper refining.
• InX-rays, it is used as an opaque medium to examine the gastrointestinal tract.
• Itis used in capacitors
• Usedin non-linear optical applications

RADIUM

Occurrence

In 1898, radium was discovered by Pierre Curie, Marie Curie,and an assistant G. Belmont. Radium compound extracted from the uraninite, hepublished the discovery at the French Academy of Sciences. By electrolysis ofradium chloride, radium was isolated in its metallic state by Marie Curie in1910. Isotopes of radium have half-lives much shorter than the age of theearth. According to the geological survey, radium would have disappeared a longtime ago. Thus it is found in unrefined uranium.

Characteristics

Radium is silvery-white metal. When exposed to air itblackens itself. It is volatile than barium. It has very high radiologicalhazards.it emits alpha, beta and gamma rays. It is a member of uranium decayseries.

Uses

• Alphaparticles that are emitted by radium were used to initiate nuclear reactions.
• Ithas a major role in medicines, particularly in the treatment of cancer by theradiation of gamma rays
• Radiumwas used for the production of luminous paints but now it is not safe to usethese paints because of its hazard property.
• Incommercially, it is used for the production of toothpaste, hair creams
• Itis also used in the production of food items due to its curing power.

REFERENCES

Atomic Number 207

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