# Chapter 2 - Chemical Formulas and Composition Stoichiometrhy - Exercises - Names and Formulas - Page 73: 14

(a)$Mg^{2+}$, it is monoatomic and it is a cation (b) $SO_{3} ^{2-}$, it is polyatomic and it is an anion (c) $Cu^{1+}$, it is monoatomic and it is a cation (d) $NH_{4} ^{1+}$it is polyatomic and it is a cation (e)$O^{2-}$ it is monoatomic and it is an anion

#### Work Step by Step

Most of these answers can be found in table 2.2. To decide if it is mono - or polyatomic you have to count the number of atoms which make up the molecule: if the number is more than one, it is polyatomic; otherwise it is monoatomic. An anion is a molecule with a negative charge, and a cation is a molecule with a positive charge.

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