Ionic Formulas

What are ions?

• Review: What’s the difference between monatomic and polyatomic ions?

Monatomic Ion – ion with only one element

Polyatomic Ion – ion with more than one element

WARNING!

• We’re going to start out with JUST MONATOMIC IONS.

• We’ll work on POLYATOMIC IONS later.

Ionic Compound

Ionic Compound – a compound in which positive and negative ions attract each other to keep matter together- Overall charge of the compound is neutral

Ionic Formula

• How do we represent an ionic compound?

Ionic Formula – Similar to a chemical formula, this shows what ions (AND how many of each ion) are in an ionic compound

Writing Ion PracticeLook at the ions and formulas listed below. Do you notice

any patterns?

Ions FormulaLi+ F- LiFNa+ Cl- NaClBe2+ O2- BeOMg2+ O2- MgOAl3+ N3- AlN

Ions FormulaLi+ O2- Li2O

Na+ N3- Na3N

Mg2+ F- MgF2

Al3+ Cl- AlCl3

Be2+ N3- Be3N2

Writing Formulas – Equal Charges

If the cation and anion charge are the same value:

Ions FormulaLi+ F- LiFNa+ Cl- NaClBe2+ O2- BeOMg2+ O2- MgOAl3+ N3- AlN

Drop the charges and write the elements

Cation first, then anion

Writing Formulas – Equal Charges

Example 1) Lithium Fluoride

Li+

F-

LiF

Writing Formulas – Equal Charges

Example 2) Magnesium Oxide

Mg2+

O2-

MgO

Writing Formulas – Different Charges

If the cation and anion charge are not equal,

1 cation and 1 anion will not form a neutral compound.

Ions FormulaLi+ O2- Li2O

Na+ N3- Na3N

Mg2+ F- MgF2

Al3+ Cl- AlCl3

Be2+ N3- Be3N2

Writing Ionic Formulas

STEP1) Write the cation

first, then the anion.

EXAMPLEAluminum Chloride

Al3+ Cl-

Writing Ionic Formulas

STEP2) Drop the + and –

(but NOT the numbers!!)

EXAMPLEAluminum Chloride

Al3 Cl1

Writing Ionic Formulas

STEP3) Cross the charges.

EXAMPLEAluminum Chloride

Al3 Cl1

Al1Cl3

Writing Ionic Formulas

STEP4) Drop any “1”.

EXAMPLEAluminum Chloride

Al1Cl3

AlCl3

Writing Ionic Formulas

STEP1) Write the cation

first, then the anion.

EXAMPLEBeryllium Nitride

Be2+ N3-

Writing Ionic Formulas

STEP2) Drop the + and –

(but NOT the numbers!!)

EXAMPLEBeryllium Nitride

Be2 N3

Writing Ionic Formulas

STEP3) Cross the charges.

EXAMPLEBeryllium Nitride

Be2 N3

Be3N2

Writing Ionic Formulas

STEP4) Drop any “1”.

EXAMPLEBeryllium Nitride

Be3N2

Be3N2

Writing Ionic Names

Rule: Cation is written as its element’s name.

Anion name ends in –ide.

**Sometimes we have to figure out the name from the formula.

Given the ionic formula, work backwards to figure out the ions.

Names – Example 1

CaBr2

Ca2+ Br-

Calcium Bromide

Names – Example 2

CoI3

Co3+ I-

Cobalt (III) Iodide

Names – Example 3

CuS

Must have the same charge:

Cu2+ S2-

Copper (II) Sulfide

Group Practice

• There are 11 stations around the room. Find them all, and write the ionic formula and name for each in your notebook.

• You will need to bring your Ion Chart with you, since some of the ions are written with NAMES, others with SYMBOLS

Group Practice - CheckStation Cation Anion Ionic

FormulaIonic Name

1 K+ O2-

2 Na+ Br-

3 Ca2+ Iodide

4 Calcium S2-

5 Al3+ Fluoride

6 Iron (III) Te2-

7 Ag+ P3-

Group Practice - CheckStation Cation Anion Ionic

FormulaIonic Name

8 Li3N

9 Ga2Se3

10 Cu2O

11 CuO

Group Practice - CheckStation Cation Anion Ionic

FormulaIonic Name

1 K+ O2- K2O Potassium Oxide

2 Na+ Br- NaBr Sodium Bromide

3 Ca2+ Iodide CaI2 Calcium Iodide

4 Calcium S2- CaS Calcium Sulfide

5 Al3+ Fluoride AlF3 Aluminum Fluoride

6 Iron (III) Te2- Fe2Te3 Iron (III) Telluride

7 Ag+ P3- Ag3P Silver Phosphide

Group Practice - CheckStation Cation Anion Ionic

FormulaIonic Name

8 Li+ N3- Li3N Lithium Nitride

9 Ga3+ Se2- Ga2Se3 Gallium Selenide

10 Cu+ O2- Cu2O Copper (I) Oxide

11 Cu2+ O2- CuO Copper (II) Oxide

Independent Practice

• Fill out the Monatomic Ions Practice