Group 1 Elements Alkali Metals
The elements of group 1 are known as alkali metals because their oxides and hydroxides are basic in nature. Aqueous solution of their oxides and hydroxides turn red litmus paper into blue.
Anomalous Properties of Lithium
Due to its exceptionally small size and high polarizing capacity, lithium shows different properties than other alkali metals.
Similarities Between Li and Mg– Lithium shows diagonal relationship with magnesium.
Lithium is harder and lighter than other alkali metals. Magnesium is also harder and lighter than other elements of the second group.
Both Li and Mg react slowly with water.
Oxides and hydroxides of Li and Mg are less soluble in water and decompose on heating.
Lithium nitride and magnesium nitride are formed by combination reaction with nitrogen.
Their oxides do not produce superoxide.
Lithium carbonate and magnesium carbonate produce oxides and carbon dioxide on decomposition.
Chlorides of both are soluble in ethanol.
Chlorides of both are deliquescent but their hydrates (LiCl.2H2O and MgCl2.8H2O) are crystalline solids.
Biological Importance of Sodium and Potassium
Sodium and potassium elements of the group 1 are of biological importance. They are important minerals of our body. Their biological importance can be described by the following points –
A human body contains approximately 0.12% of Na and 0.25% of K.
Sodium ions are found in blood plasma and interstitial fluid.
Sodium ions help in transporting the signals from nerve cells, regulating the water flow across cell membranes, transport of sugars and amino acids to cells.
Sodium ions also help in activation of various enzymes.
Potassium ions also help in the transmission of nerve signals and transportation of essential compounds to cells.
Potassium ions are the most abundant positive ions within cell fluids.
Potassium ions activate many enzymes which help in production of energy by oxidation of glucose.
Sodium – potassium pump which operates across the cell membrane is based on the sodium and potassium ions.
Sodium and potassium ions differ in their concentrations in the cell fluid and also differ quantitatively in their ability to penetrate the cell membrane.
The elements of group 2 are known as alkaline earth metals because their oxides and hydroxides are basic in nature and these metals are found in earth or earth’s crust. Aqueous solution of their oxides and hydroxides turn red litmus paper into blue.
Anomalous Behavior of Beryllium
Due to its exceptionally small size and high ionization enthalpies, beryllium shows different properties than other alkaline earth metals or 2nd group elements.
Similarities Between Be and Al – Beryllium shows diagonal relationship with aluminum. Some similarities between the are listed below –
Aluminium and beryllium both do not attack acids easily.
Beryllium hydroxide and aluminium hydroxide both give beryllium ion and aluminium ion respectively on dissolving in excess of aqueous solution of base.
In vapor phase chlorides of both Al and Be show chloride bridge structure.
Chlorides of both are strong Lewis acids and soluble in organic solvents.
Ions of both form complexes such as BeF42-, AlF63- etc.
Biological Importance of Magnesium and Calcium
Magnesium and calcium are the elements of the group 1 which has biological importance. They are important minerals of our body. Their biological importance can be described by the following points –
Calcium is necessary for our healthy bones. Almost 1200g of calcium is found in the body of an adult.
Magnesium is important for various enzymes involved in the utilization of energy (ATP). Almost 25g of Mg is found in the body of an adult human being.
Chlorophyll which is found in the leaves contains Mg.
Ca is necessary for proper growth of our body.
Ca is important for healthy teeth as well.
Calcium plays a vital role in blood coagulation, neuromuscular function and building of cell walls in plant cells.
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