What are POLYATOMIC IONS?

What are POLYATOMIC IONS? Lets first review what a monatomic ion is What is a group of atoms with charge? back to naming compounds

In a single atom (monatomic), charge results from having either more electrons or less electrons than protons. More electrons than protons = negative charge (anions) + + Less electrons than protons = positive charge (cations)

Mg 2+ Example: The magnesium ion has two less electrons than protons

2+ two less electrons than protons Mg Example: The magnesium ion has back to polyatomic ions Example: The magnesium ion has two less electrons than protons

N O

two or more atoms covalently bonded together. In a polyatomic ion, two or more atoms covalently bonded together. N O

1– N O Together, they carry a charge

1– The nitrate ion (NO3–) has, in total, one more electron than protons

Mg(NO3)2 When balancing charges in an ionic compound, the polyatomic ion acts as a single unit of charge: N O 1- N O 1- Mg 2+ Mg(NO3)2

1- 1- 2+ N O N O Mg Mg(NO3)2 2+

1- the charges are balanced 1- 2+ N O N O Mg Mg(NO3)2 2+ 2-

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