The s-block Elements Alkali Metals: General Characteristics and Properties The group1 metals are called the alkali metals. They are the most reactive metals. They all have 1valence electron and all form +1 cations. The alkali metals are good conductors, and they have a shiny, silvery appearance. In flame tests, lithium forms a candy-apple red colour, while sodium produces a yellow flame and potassium a lilac flame. They react with hydrogen to form metal hydrides. They react with halogens to form alkali metal halide salts, such as NaCl. They react with oxygen – lithium forms oxides, sodium forms peroxides, and the other group 1 metals form superoxides. Alkali metals react vigorously with water to produce hydroxide ions in solution, and hydrogen gas. Alkali Metals: Anomalous Properties and Compounds Lithium exhibits some anomalous behavior and it exhibits a “diagonal relationship” with magnesium. Sodium carbonate, or washing soda, Na 2CO 3, can be formed by the four-step Solvay process. Sodium Chloride, or table salt, NaCl, can be isolated from sea water. Sodium hydroxide, NaOH, can be prepared by the electrolysis of brine solution in the Castner- Kellner cell. Baking soda, or sodium hydrogen carbonate, NaHCO 3, can be produced by reacting sodium carbonate solution with carbon dioxide. Sodium ions play important roles in transmitting nerve signals, regulating water transport into cells, and transporting nutrients into cells. Potassium ions are essential for activating enzymes, the metabolism of ATP in cells, and transmitting nerve signals. Alkaline Earth Metals: General Characteristics and Properties The group1 metals are called the alkali metals. They are the most reactive metals. They all have 1valence electron and all form +1 cations. The alkali metals are good conductors, and they have a shiny, silvery appearance. In flame tests, lithium forms a candy-apple red colour, while sodium produces a yellow flame and potassium a lilac flame. They react with hydrogen to form metal hydrides. They react with halogens to form alkali metal halide salts, such as NaCl. They react with oxygen – lithium forms oxides, sodium forms peroxides, and the other group 1 metals form superoxides. Alkali metals react vigorously with water to produce hydroxide ions in solution, and hydrogen gas. Alkaline Earth Metals: Anomalous Properties and Compounds Beryllium exhibits anomalous behavior and has a diagonal relationship with aluminium due to their similar charge/radius ratios. Calcium oxide, CaO, commonly known as quicklime, is formed from the decomposition of calcium carbonate. Slake lime, or calcium hydroxide, Ca(OH) 2, is sparingly soluble in water. Lime water, a suspension of calcium hydroxide, can be used to test for the presence of carbon dioxide. Calcium carbonate, CaCO 3, is nearly insoluble in water, and occurs naturally as limestone, marble and chalk. Plaster of Paris is a hemihydrates of calcium sulphate. The main components of cement are calcium oxide and silicon dioxide. Magnesium is found in chlorophyll and as cofactors in certain enzymes. Calcium is important in bone structure, muscle contraction and other biological processes. .