3 of 39 Where are the alkali metals? The elements in group 1, on the left of the periodic table, are called the alkali metals. These metals are all very reactive and are rarely found in nature in their elemental form. lithium sodium potassium rubidium caesium francium Fr Cs Rb K Na Li
9 of 39 What are the properties of the alkali metals? The characteristic properties of the alkali metals are: They are shiny. This is only seen when alkali metals are freshly cut. They are good conductors of heat and electricity. They are soft and can be cut by a knife. Softness increases going down the group. They have a low density. Lithium, sodium and potassium float on water. They have low melting and boiling points. These properties mean that the alkali metals are different to typical metals. However, alkali metals do also share some properties with typical metals:
17 of 39 How do the alkali metals react with oxygen? All alkali metals react with oxygen in the air to form metal oxides. This produces a layer of dull oxide on the surface of the metal, called tarnish. The speed with which alkali metals react with oxygen in the air increases going down the group: Why are alkali metals stored in oil? lithium – tarnishes slowly sodium – tarnishes quickly potassium – tarnishes very quickly. The oil prevents them from reacting with oxygen and tarnishing.
35 of 39 Glossary alkali metal – An element that belongs to group 1 of the periodic table. exothermic – A reaction that releases heat into its surroundings. metal chloride – The type of solid produced when an alkali metal is burned in chlorine gas. metal hydroxide – The type of alkali produced by the reaction between an alkali metal and water. metal oxide – The type of solid produced when an alkali metal reacts with oxygen. oxidation – The process by which a substance reacts and combines with oxygen. tarnish – The discolouration of metal after exposure to air caused by the formation of an oxide on the metal’s surface.