QOTD What do you call a negatively charged atom? What do you call a positively charged atom? Do you think there is a way to name polyatomic ions? Why or why not? List 4 polyatomic ions. What does poly mean?

Compounds & Nomenclature Polyatomic Ions Compounds & Nomenclature

Objectives Define a polyatomic ion Name compounds containing a polyatomic ion. Given the name of a compound containing a polyatomic ion, write its formula.

Define a polyatomic ion Polyatomic Ion: An ion (either positively or negatively charged) composed of two or more atoms.

Is it possible to predict charges? Based on covalent bonding Charges of polyatomic ions are based on overall stability Not as predictable as monatomic ions These will have to be memorized However, this becomes easy with practice

Common Examples HCO32- Bicarbonate Ion PO43- Phosphate Ion NH4+ Ammonium Ion NO3- Nitrate Ion

Name compounds containing a polyatomic ion Example: NaNO3 If the compound contains a metal cation, the name of the metal comes first.

Name compounds containing a polyatomic ion Example: NaNO3 If the compound contains a metal cation, the name of the metal comes first. Sodium

Name compounds containing a polyatomic ion Example: NaNO3 2 Name compounds containing a polyatomic ion Example: NaNO3 2. The second part of the name is just the name of the polyatomic ion Sodium

Name compounds containing a polyatomic ion Example: NaNO3 2 Name compounds containing a polyatomic ion Example: NaNO3 2. The second part of the name is just the name of the polyatomic ion Sodium Nitrate

What if the Polyatomic Ion comes first? NH4+ (Ammonium ion) is a positive ion while still being polyatomic If you are using a polyatomic cation you just use the ion’s name, and it will be written first NH4Cl

What if more than one Polyatomic Ion is needed? Compounds must be neutral! If > 1 polyatomic ion is needed in a formula, it will be put in parentheses before the subscript When writing its name, it will just remain the name of the polyatomic ion Al2 (SO4)3

Given the name of a compound containing a polyatomic ion, write its formula. Example: Potassium Carbonate 1. Determine atomic symbols and charges

Given the name of a compound containing a polyatomic ion, write its formula. Example: Potassium Carbonate 1. Determine atomic symbols and charges K+ CO32-

Given the name of a compound containing a polyatomic ion, write its formula. Example: Potassium Carbonate 2. Determine number of each ion to balance charges K+ CO32-

Given the name of a compound containing a polyatomic ion, write its formula. Example: Potassium Carbonate 2. Determine number of each ion to balance charges 2K+ 1CO32-

Given the name of a compound containing a polyatomic ion, write its formula. Example: Potassium Carbonate 3. Using symbols for both ions and proper subscripts, write the formula K2CO3

Practice Examples 1. BeSO3 2. NaC2H3O2 3. Ca(NO3)2 4. Aluminum Nitrite 5. Iron (II) Hydroxide 6. Ammonium Phosphate

NEW SEATING! CHECK THE CHART! QOTD Name/Write the Formula 1. MgSO3 2. NaF 3. OH 4. Aluminum Nitrate 5. Iron (III) Phosphate 6. Ammonium Hydroxide

Happy Thanksgiving Break!