 In this lesson, we will learn about the alkaline earth metals in group 2 of the periodic table. We will focus on magnesium and calcium, and learn about how they react with oxygen and water and the products formed from these reactions. The alkaline earth metals are beryllium, magnesium, calcium, strontium, barium, and radium, located in group 2 of the periodic table. These metals all have two electrons in their valence shell, and with the exception of beryllium, can lose these valence electrons to form an ion with a plus 2 charge. Like the alkaline metals, these metals, except for magnesium, are stored in oil. Similar properties and reactivity trends are also observed. Counting down the group, their density and reactivity increases. Melting points and boiling points decrease, and the metals become softer. We will now learn about the reactions of magnesium and calcium with oxygen and water. Magnesium is shiny and silver, but you will see that your magnesium strip may be dull. This is due to the formation of an oxide layer from exposure to air. We clean it with steel wool, so to remove as much of the oxide layer as possible. Using a pair of tongs, take the magnesium strip and hold it to a roaring Bunsen burner flame. The combustion of magnesium proceeds with a bright white flash. Take care not to look at this flash. Calcium reacts with oxygen to produce magnesium oxide, which is a white solid. Here is a challenge. Do you expect calcium to be softer or harder than magnesium? Please pause the lesson to think about this and resume when you are ready. Calcium is softer than magnesium. Moving down the group, the metals become softer. Overall though, these metals are harder than the alkali metals. Calcium is also shiny and silver. Using a pair of tweezers, take out a chunk and cut a small piece using a scalpel. Remove excess oil using paper towels. Using tongs, place in a roaring Bunsen burner flame. You will observe that it burns with a red flame. Calcium reacts with oxygen to produce calcium oxide, which is a white solid. So magnesium and calcium react with oxygen to form their respective oxides. Let the formed calcium oxide cool. It's important that you allow it to cool sufficiently because the next step is exothermic. Place the cooled calcium oxide in cold water. Calcium oxide reacts with water to produce a solution of calcium hydroxide, also known as lime water. You will see a white precipitate at the bottom of the beaker once everything settles. This is solid calcium hydroxide as it is only slightly soluble in water. Magnesium will only react with steam, not cold water. The reaction from steam forms magnesium oxide and hydrogen gas. In this practical, it is imperative that the magnesium strip is heated, not the mineral wool soaked in water. Hydrogen gas can be collected over water and tested to confirm its presence. How do you think the reaction of calcium with water compares to the reaction of magnesium with water? Please pause the lesson to think about this and resume when you are done. The reaction of calcium with water is expected to be more vigorous as the reactivity of these metals increases moving down the group. Calcium reacts with cold water to form calcium hydroxide and hydrogen gas. Note that calcium sinks to the bottom in this reaction. The effervescence shows that a gas is being produced. In summary, the alkaline earth metals are the group 2 metals. They exhibit similar properties and reactivity trends to the alkaline metals. Magnesium and calcium react with oxygen to form their respective oxides. Magnesium reacts with steam to produce magnesium oxide and hydrogen gas. Calcium reacts with cold water to produce calcium hydroxide and hydrogen gas.