Demo: Sodium reaction with water Note: wear safety equipment as the reaction is highly reactive and can burn easily Point to review: Sodium’s symbol is Na Sodium is an Alkali Metal Alkali Metals are very reactive because they have 1 valence electron Alkali Metals are silver-grey, malleable, ductile, have luster Water has H and O When a metal reacts with a non-metal we get ionic bonding How many valence electrons does Na, H, and O have 1: Freshly cut sodium has a metallic sheen. Within a few minutes, water in the air causes a layer of sodium hydroxide to develop on exposed surfaces, which is why elemental sodium is stored under hexane or a similar substance. 2: Sodium reacts with water, here as an acid, according to: 2 Na + 2 H2O > 2 NaOH + H2 3: The reaction is strongly exothermic: The piece of sodium melts (melting point of sodium: 97.8 °C). The heat transferred to the local environment can ignite the hydrogen that is produced. 4: The hydrogen may burn with a bright flame. All the alkali metals react with water to produce elementary hydrogen and the corresponding alkali hydroxides. The reactivity increases with increasing periodic number. The metals rubidium and cesium explode when brought into contact with oxygen.