By: Faraz Class: 9B Block 8 Chemistry Alkaline Earth Metals By: Faraz Class: 9B Block 8 Chemistry

What are “Alkaline Earth Metals”? Alkaline Earth metals are metallic elements found in the 2nd group of the periodic table. This is the list of all alkali earth metals: -Beryllium -Magnesium -Calcium -Strontium -Barium -Radium They are placed in the periodic table next to the Alkali Metal group.

Why are they called Alkaline earth metals? They are mainly called alkaline earth metals because they are found in the earth’s crust. They are distributed in rock structures.

Details of the elements Symbol Atomic Number Melting Point /K Density/kg m-3 Beryllium Be 4 1551 1847 Magnesium Mg 12 922 1738 Calcium Ca 20 1112 1550 Strontium Sr 38 1042 2540 Barium Ba 56 1002 3594 Radium Ra 88 973 5000

Physical Properties They are malleable (soft) They are lustrous (shiny) They have low densities (able to float on water) Good conductor of heat and electricity Low melting and boiling points They have almost all the same properties that alkali metals have

Chemical Properties The alkaline earth metals are high in the reactivity series of metals, but not as high as the alkali metals of Group 1. Due to their high levels of reactivity, the alkaline earth metals rarely appear by themselves in nature; rather, they are typically found with other elements in compound form, often as carbonates or sulfates. This, again, is another similarity with the alkali metals. But whereas the alkali metals tend to form 1+ cations (positively charged atoms), the alkaline earth metals form 2+ cations—that is, cations with a positive charge of 2. As you go down the table they get more reactive. They react with water and air. All alkaline earth elements have an oxidation number of +2, making them very reactive.

Reactions with Water When added to water, the first alkaline earth metal (Beryllium) is totally unreacative, and doesn't even react with steam. Then as you move down the group, the reactions become increasingly vigourous. Example:- -Mg + H2O → MgO + H2 -Ca(s) + H2 → CaH2

Reactions with Air The reactivity towards oxygen increases as we go down the group. Thus Ca, Ba and Sr are stored in paraffin but Be and Mg are not because they form protective oxide layer on their surface. Example:- -2Be + O2 (air) → 2BeO -Mg + air → MgO + Ng3N2

Discovery Beryllium was discovered by Nicholas Louis Vauquelin in 1797. Magnesium was discovered by Sir Humphrey Davy in 1808. Calcium was discovered by Sir Humphrey Davy in 1808. Strontium was discovered by Adair Crawford in 1790. Barium was discovered by Sir Humphrey Davy in 1808. Radium was discovered by Pierre and Marie Curie in 1898.