Final answer:
Polyatomic ions are groups of atoms with an overall electric charge. Common ones include nitrate (NO3-) and ammonium (NH4+). They are typically written within brackets with their charge as a superscript.
Step-by-step explanation:
Polyatomic ions are groups of atoms bonded together with an overall electric charge. They have characteristic formulas, names, and charges. Some common polyatomic ions include nitrate (NO3-), ammonium (NH4+), and hydroxide (OH-). These ions are often written within a large set of brackets, with their charge as a superscript outside the brackets.