# Writing Ionic Formulas and Naming Ionic Compounds Writing

• Slides: 12

Writing Ionic Formulas and Naming Ionic Compounds

Writing Formulas Hint: Switchy-Switchy Example: Let’s make a compound using magnesium and chlorine • Steps • 1. Write each element with its charge (Periodic Table Columns can help with this) • 2. Switchy-Switchy Example Mg +2 Cl -1

Writing Formulas Hint: Switchy-Switchy Example: Let’s make a compound using magnesium and chlorine • Steps • 1. Write each element with its charge (Periodic Table Columns can help with this) • 2. Switchy-Switchy • 3. Reduce Example Mg 1 Cl 2

Naming Ionic Compounds • Example: Mg. Cl 2 • Steps • 1. Name the metal (cation) • 2. If the metal is a transition element, you must add a Roman Numeral in ( ) for the charge number (oxidation number) • 3. Name the non-metal (anion) changing ending to –ide Magnesium Chloride

Let’s look at Ti. O Titanium (II) Oxide Is titanium a transition element? Then we need a Roman Numeral But which one? We need to balance the charge The charge of O is _____, -2 so we must +2 be using a Ti with a charge of _____. Remember Switchy-Switchy then reduce

Anion Endings • If you see a name that ends in –ide, you are dealing with an element, unless peroxide, hydroxide, or cyanide • If you see a name that ends in -ate or –ite, you are dealing with a polyatomic ion (Page 178 or back of periodic table)

Polyatomic Hint • Nick the Camel ate Supper in Phoenix. • OH Nicky! • In the first saying, the first letter gives element, number of consonants gives number of oxygens, and number of vowels give charge. • Second is for Hydroxide (OH-) and ammonia (NH 4+)

How to read/name Polyatomic Ions • The first “rule” looks at the number of oxygens in an ion • Think of the -ate ion as being the "base" name • The per- prefix adds an oxygen. • -ite will reduce the oxygens by one. • Adding hypo- to the –ite version will reduce the number of oxygens by another 1 • In all situations, the charge is NOT affected.

For example, let’s look at the polyatomic ions that involve chlorine • Cl- chloride • Cl. O- hypochlorite • Cl. O 2 - chlorite • Cl. O 3 - chlorate • Cl. O 4 - perchlorate

How to read/name Polyatomic Ions • “Rule 2”: when the prefix bi- is added to a name, a hydrogen is added to the ion's formula and its charge is increased by +1 • An Example: • Carbonate – CO 32 • Bicarbonate – HCO 3 -

How to work with polyatomic ions • Think of them as a single ion • All the atoms stay together and if you need more than one, you have to use parenthesis. • For example, Magnesium Hydroxide +2 -1 Mg ( OH ) 2

Practice Cation Anion Name Formula Li+ Br- Lithium bromide Li. Br Na+ O-2 Sodium oxide Na 2 O Pb+2 F- Lead (II) Fluoride Pb. F 2 Mg+2 PO 4 -3 Cu+ CO 3 -2 Copper (I) Carbonate Cu 2 CO 3 SO 4 Ammonium sulfate (NH 4)2 SO 4 NH 4 + -2 Magnesium phosphate Mg 3(PO 4)2