The NH4 asked about is the amonium ion, and it's written NH4+ to indicate it has a positive charge (+1). It's a cation. Wikipedia has more information on this chemically â¦ significant polyatomic ion, and you'll find that a link to that post is provided below. + 7 others found this useful.
Gilbert is a town in Maricopa County, Arizona, United States, just southeast of Phoenix, within the Phoenix metropolitan area.
Gilbert owes its beginnings to William Bobby Gilbert who provided land to the Arizona Eastern Railway in 1902 to construct a rail line between Phoenix and Florence, Arizona. Ayer's Grocery Store, the first store in Gilbert, opened in 1910 and became the location of the first post office in 1912.