Guided Notes 4 a Bonding Polyatomic Ions you

Guided Notes 4 a Bonding (Polyatomic Ions) *you NEED your Polyatomic Reference Sheet to understand where the names are coming from*

Go with this example… • Pretend Mrs. Shorette is a CATION (has energy/electrons to GIVE). She has 1 valence electron because she is from Group 1. • Rancho High School is an ANION (needs to TAKE electrons to be stable). Rancho needs 2 valence electrons (two sets of classes) because they are from Group 16. • Mrs. Shorette cannot make an IONIC BOND with Rancho High School’s needs. Welcome back Chemistry classes! Come back home (room 1009) on Monday!

What blue color means • Throughout the slides you will see BLUE text. This text is additional information. You may add this information to your notes if it will help you!

What are polyatomics? • Polyatomics: ions made of a __groups of atoms__ • Example: ammonium __ (NH 4) • phosphate__(PO 4)3 • Hint- we find out the names of the (polyatomics) by looking at our Reference Sheet

How are polyatomics used in ionic compounds? • Some __can lose/give__ electrons like a metal and become a __cation__ • Example: ammonium (NH 4)+ • Most __will take__ electrons like a nonmetal and become an __anion__ • Example: phosphate (PO 4)3 -

How do you determine the formula using polyatomics? • Cross-down method (we find the charges of the polyatomics by looking at the Reference Sheet) • (NH 4)1+ O 2_(NH 4)2 O_ (NH 4)1+ We find the 1+ on the Reference Sheet O 2 - Like before, we use the Group # to tell us that Oxygen NEEDS to TAKE 2 more valence electrons to be stable/complete

Continued Example • Na+ (PO 4) 3 • Na 1+ __Na 3(PO 4)__ Sodium is in Group 1 and wants to GIVE away its 1 valence electron (you can just put a + to represent 1+) • (PO 4)3 - We find the 3 - on the Polyatomic Reference Sheet

How do you name these compounds? • Positive ion is __1 st__ • Negative ion is __2 nd__ • “ide” ending __not used_ if elements are in brackets, then see Reference Sheet • Note- Polyatomic name replaces the original ending.

Example (for naming) • Sodium phosphate: Na 3 (PO 4) • Na 3 is Sodium • (PO 4) because it is in parenthesis we look at our Reference Sheet and find the name

Check for Understanding *Use your flow chart on the Reference Sheet* • What is the name of Mg(SO 4) _Magnesium _ _Sulfate_ What is the name of (NH 4) Cl _Ammonium_ _Chloride_

Add to the bottom of your notes: • Anytime you see ( ) they represent a polyatomic ion= check your table for their charge