What are you thinking when you see these images?

As much as we love (or hate) hotdogs... Hotdogs contain many chemical additives Sodium is needed in our diet in specific amounts (Recommended Daily Value is mg). Processed foods contain a lot of sodium (eg. NaCl) which can extend its shelf life. Nitrites have a bad rep as they may be linked to cancer BUT studies have shown that nitrites in the body can protect the heart tissue after a heart attack. Look at a food label and see the “chemicals”.... You will often find a lot of polyatomic ions.

Polyatomic Ions

A type of ion that consists of a group of several atoms acting together as a single charged particle. The ionic charge is shared over the entire group rather than just one atom. Example: Nitrite ion NO 2 − −

Common Polyatomic Ions (p. 161) Name of Polyatomic IonIon FormulaIonic Charge nitrateNO nitriteNO hydroxideOH carbonateCO hydrogen carbonate (bicarbonate)HCO sulphateSO sulphiteSO phosphatePO phosphitePO ammonium **will go first in naming**NH permanganateMnO

Naming Compounds with Polyatomic Ions Step 1: Name the metal first. Step 2: Identify the polyatomic ion and name it second. Step 3: Combine the names. Note 1: Watch out for multivalent metals! Use Roman numerals to indicate the correct charge. Note 2: If ammonium (NH 4 ) is present, it will go 1 st in the naming.

a) K 2 CO 3 b) Ca 3 (PO 3 ) 2 c) (NH 4 ) 2 SO 4

Writing Formulas for Compounds with Polyatomic Ions a) copper(II) nitrate Step 1: Write the symbol of each ion, with its ionic charge. Cu 2+ (NO 3 ) - Step 2: Crisscross the #s of the ionic charges so that they become subscripts. Cu 2+ (NO 3 ) - Step 3: Write any necessary subscripts after the brackets around each ion. Reduce the formula if necessary. The formula of copper (II) nitrate is: Cu(NO 3 ) 2 Note: Brackets used if you have more than 1 unit of the polyatomic ion!

b) aluminum hydrogen carbonate c) iron(III) sulphate