The group two elements consist of Beryllium, Magnesium, Calcium, Strontium, Barium and Radium. These are known as the ‘Group Two elements’ because of their unique electron division. Each one of these elements, consists of two outer shell electrons. Because of the lack of outer electrons, these elements are highly reactive. Group two electrons have a positive Two charge or +ve. The Group 2 elements are all metals with a shiny, silvery-white colour.
The alkaline earth metals are high in the reactivity series of metals, but not as high as the alkali metals of Group 1.These elements are all found in the Earth’s crust, but not in the elemental form as they are so reactive. Instead, they are widely distributed in rock structures. The metals of Group 2 are harder and denser than sodium and potassium, and have higher melting points. The chemical properties of Group 2 elements are dominated by the strong reducing power of the metals. The elements become increasingly electropositive on descending the Group. The last element in Group 2, Radium, is not yet definite in terms of melting points or density due to its very strong radioactivity emission.
Beryllium is used for X-ray windows (Beryllium transmits X-rays 17 times better than aluminium), as a 2% alloy with nickel for springs, electrodes and non-sparking tools. Beryllium (2%) alloyed with copper gives a hard strong alloy with high resistance to wear used in gyroscopes, computer parts, and instruments. Magnesium is used in flares and pyrotechnics, including incendiary bombs. It was used in flash photography and is lighter than aluminium. It is also used in alloys used for aircrafts, car engine casings, and missile construction. Calcium is a reducing agent for the preparation of metals such as thorium, uranium, zirconium, etc.
Alloys of calcium with agent for Aluminium, Beryllium, Copper, Lead, and Magnesium have some useful properties toward construction areas. Calcium is known as a “getter” for residual gases in vacuum.Calcium from limestone is a component of Portland cement. Mixed with sand it hardens as mortar and plaster while taking up carbon dioxide from the air. Strontium is used as fireworks flares. 90Sr is a radioactive isotope produced by nuclear fallout.
90Sr has the potential for use as lightweight nuclear producing electricity. Strontium is also used; to produce glass for colour television tubes, refining zinc and production in optical materials. Barium is used in paint and more importantly in X-ray diagnostic work. Barium is also a strong contender for glassmaking. Barite is extensively used as a weighting agent in oil rigs.
The carbonate form is a rat poison. Radium is limited in its use due to its radioactivity. It is mainly used on self-luminous paints and treatment of conditions such as cancer (now being replaced by 60Co sources).Lime (calcium oxide) and slaked lime (calcium hydroxide) are both used to reduce the acidity of soil on land, they are both faster and stronger acting than limestone powder. They are also used to reduce acidity in lakes and rivers due to acid rain.
and to neutralise potentially harmful industrial acid waste including sulphur dioxide in the flue gases of power stations. Quicklime (CaO) is made by heating limestone (CaCO3) and changes into slaked lime, Ca(OH)2, on the addition of water. It is a cheap base for the chemical industry with many uses. When limestone is heated in a kiln at over 900oC, it breaks down into quicklime (calcium oxide) and carbon dioxide.
Both are useful products.This type of reaction is endothermic and an example of thermal decomposition. This is a reversible endothermic reaction. To ensure the change is to favour the right hand side, a high temperature of over 900oC is needed as well as the continual removal of the carbon dioxide.
The high temperature needed is produced by mixing the limestone with coal/coke (a fuel of mainly carbon) and blowing hot air into the ignited mixture in a rotating kiln for a continuous production line. Quicklime reacts very exothermically with water to produce slaked lime.As seen above, group two elements and compounds play a huge role in today’s societies. Most industrial procedures that take place, used group two elements and compounds in one form or the other.
One example was the use of thermal decomposition to produce lime and slaked lime. This is a very good acid neutraliser that has helped reduce the effects of acid rain on agricultural areas and save lake habitants such as fish from death by neutralising the active hazardous acid. Another issue involving the group two elements, are its participation with water. Magnesium Ions are in all water, as we rarely use its purified version. Due to the participation of Magnesium, Carbon dioxide reacts with water to form carbonic acid which at ordinary environmental pH exists mostly as bicarbonate ions.Microscopic marine organisms take this up as carbonates to form calcite skeletons which, over millions of years, have built up lots of limestone deposits. Ground waters, made slightly acidic by CO2 (both that absorbed from the air and from soil bacteria) dissolve the limestone, therefore enduing up with calcium and bicarbonate ions and becoming “hard”. All of the above only forms a very small minority of the potential of group two elements, which gives us an indication of the importance and significance that they all posses to one and other and most importantly, to us and the daily industrial procedures carried out.