Base (chemistry) Base (chemistry) In chemistry, bases are substances that, in aqueous solution, release hydroxide (OH) ions, are slippery to the touch, can taste bitter if an alkali, change the color of indicators (e.g., turn red litmus paper blue), react with acids to form salts, promote certain chemical reactions (base catalysis), accept protons from any proton donor or contain completely or partially displaceable OH ions. Examples of bases are the hydroxides of the alkali metals and the alkaline earth metals (NaOH, Ca(OH), etc., see alkali hydroxide and alkaline earth hydroxide). These particular substances produce hydroxide ions (OH) in aqueous solutions, and are
Chemistry: A Volatile History elements to Lavoisier's list, as well as confirming that substances like chlorine and iodine were also elements. By the time of his death in 1829 the idea of the elements was firmly established, 55 separate elements had been discovered, and the world had a new science: Chemistry. At the beginning of the 19th century only 55 of the 92 naturally occurring elements had been discovered. Scientists had no idea how many more they might find, or indeed if there were an infinite number of elements. They also sought to answer a fundamental question, namely: is there a pattern to the