This page describes the reactions of the Period 3 elements from sodium to argon with water, oxygen and chlorine. Sodium has a very exothermic reaction with cold water producing hydrogen and a colourless solution of sodium hydroxide. Magnesium has a very slight reaction with cold water, but burns in steam.
Number 4 (四; accounting 肆; pinyin sì) is considered an unlucky number in Chinese because it is nearly homophonous to the word “death” (死 pinyin sǐ). Due to that, many numbered product lines skip the “4”: e.g., Nokia cell phones (there is no series beginning with a 4), Palm PDAs, Canon PowerShot G’s series