Final answer:
A group of two or more elements that stay together and act as a single ion is called a polyatomic ion.
Step-by-step explanation:
A group of two or more elements that stay together and act as a single ion is called a polyatomic ion. These ions consist of groups of atoms covalently bonded together and have an overall electric charge. Common examples include the sulfate dianion (SO42-), nitrate anion (NO3-), and phosphate trianion (PO43-).