A compound is a chemical substance that forms when two or more different elements combine in a fixed ratio. Water (H2O), for example, is a compound that is made up of two hydrogen atoms for every one oxygen atom. Sodium chloride (NaCl) is a compound made up of one sodium atom for every chlorine atom.
Hudson, Iowa. Hudson is a city in Black Hawk County, Iowa, United States. The population was 2,282 at the 2010 census. The rural community of Hudson has grown in recent years and is included as a part of the Waterloo-Cedar Falls Metropolitan Statistical Area. Contents.
Hudson is a city in St. Croix County, Wisconsin, United States. As of the 2010 United States Census, its population was  18,937, making it the principal and largest city of the Minneapolis - St. Paul metropolitan area (Wisconsin suburbs). The Hudson area however had a population of 39,713. The village of North Hudson is located directly to the north of Hudson. Hudson was settled in the summer of 1840 by Louis Massey and his brother in-law, Peter Bouchea. William Steets arrived at about the same time.