#chemical structures

• Alkaline earth — Pertaining to or characteristic of the group of bivalent chemical elements in group 2 of the periodic table (such as beryllium, magnesium, calcium, strontium, barium, and radium). The name originates from the fact that the oxides of these metals exhibit pronounced alkaline properties and were historically called 'earths' due to their insolubility and high resistance to elevated temperatures.
• Alkane — A generic name given to saturated acyclic hydrocarbons with linear or branched chains, containing exclusively single sigma bonds between carbon atoms and having the general molecular formula CnH2n+2. Alkanes (historically termed paraffins) exhibit relatively low chemical reactivity at room temperature and constitute the primary component of natural gas and petroleum (e.g., methane, ethane, propane, butane).
• Asparagine — A non-essential amino acid, being the first one historically isolated from natural sources (asparagus juice in 1806); it plays a crucial role in human protein biosynthesis, central nervous system metabolism as a neurotransmitter precursor, and in the clearance of toxic ammonia from the body via urea transformation; it is also a key structural compound in the nitrogen metabolism of many higher plants.