 | |
|
Alkali
and Alkaline Earth Metals Concept Periodicity - element physical properties, reactivity Overview Alkali and alaline earth metals are among the most reactive elements. Alkali metals are shiny and soft, and are more reactive than alkaline earth metals. Sodium is more reactive than lithium, and calcium is more reactive than magnesium. Safety Goggles must be worn. Sodium and lithium should be handled with gloves and kept from water except in small quantities. Procedure Remove lithium or sodium from its vial with forceps, wipe off the mineral oil with a paper towel, and place on a dry watch glass. Cut into the metal with a razor to show that it is soft and that the freshly cut (unoxidized) surface is shiny. Using the forceps, place a pea-sized piece of the metal into a watch glass containing water. The metal will fizz, may spark (pieces this size are unlikely to produce flames), and will dart across the water surface until it has dissolved. Pass around watch glasses containing calcium turnings and magnesium ribbon. Drop pieces into water and then into acid to show that they are not as reactive as alkali metals. If there is time, one can touch pH paper to water that had sodium or lithium added to it to show that it has become basic. (Sodium reacts with water to form NaOH, lithium to form LiOH.) Disposal Lithium and sodium that has been taken out from the oil should be allowed to completely react with water, then they, reacted calcium and magnesium, water, and acid can be poured down the drain. Materials
|