Ionic/Covalent Compound Names and Formulas Ionic/Covalent Compound Names and Formulas

We want to bond Magnesium and Oxygen

Step 1: What are the oxidation states? Use the periodic table trick:

To be balanced, the net (overall) charge MUST be ZERO. Step 2: Are charges balanced? Mg +2 O -2 How many positive charges are there? How many negative charges are there?

Step 3: Figure out your formula What is ? Is the overall charge zero? So what is your formula? MgO What is ? Is the overall charge zero? So what is your formula? MgO Mg +2 O -2

Step 4: What is your compound called? The cation ALWAYS comes first and keeps its name the way it is written. –Magnesium The anion ALWAYS comes second and the end comes off and is replaced with -ide –Oxygen gets changed to oxide Magnesium Oxide The cation ALWAYS comes first and keeps its name the way it is written. –Magnesium The anion ALWAYS comes second and the end comes off and is replaced with -ide –Oxygen gets changed to oxide Magnesium Oxide Mg +2 O -2

Let’s Practice Let’s combine Magnesium and Chlorine.Let’s combine Magnesium and Chlorine. Step 1: What are the ox. states?Step 1: What are the ox. states? Let’s combine Magnesium and Chlorine.Let’s combine Magnesium and Chlorine. Step 1: What are the ox. states?Step 1: What are the ox. states?

Step 2: Are the charges balanced? Is the overall charge ZERO? NO! We have too many positive charges. Step 2: Are the charges balanced? Is the overall charge ZERO? NO! We have too many positive charges. Mg +2 Cl -1 How many positive charges are there? How many negative charges are there?

What do we do now? How can we make the charges balance? Mg +2 Cl

What’s the formula? What would the formula for this ionic compound be? MgCl 2 What would we call it? Magnesium chloride What would the formula for this ionic compound be? MgCl 2 What would we call it? Magnesium chloride Cl -1 Mg +2

Try the following: With your neighbor, make a balanced formula and the correct names for these ionic compounds: 1.Na + Cl 2.Al + Cl 3.Mg + S 4.K + O 5.Na + O 6.Ca + F 7.Al + O (This one’s hard!)

IonsCationAnionFormulaCompound Name Na + Cl Na +1 Cl - 1 NaClSodium chloride Al + Cl Al +3 Cl -1 AlCl 3 Aluminum chloride Mg + S Mg +2 S -2 MgSMagnesium sulfide K + O K +1 O -2 K2OK2OPotassium oxide Na + O Na +1 O -2 Na 2 OSodium oxide Ca + F Ca +2 F -1 CaF 2 Calcium fluoride Al + O Al +3 O -2 Al 2 O 3 Aluminum oxide

Covalent Compound Names/Formulas

Remember this…. A covalent compound forms between two or more nonmetals so we don’t have to worry about ion formation or oxidation states.

A simple set of rules can be used to name them: Step 1: Name the elements in the order they appear in the formula. For example, CO 2 would be named carbon oxygen. Or is it?

What about the subscripts? Step 2: Use prefixes to indicate how many elements there are of each type. This rule may be modified to improve how the name sounds.

PrefixNumeric value Mono-1 Di-2 Tri-3 Tetra-4 Penta-5 Hexa-6 Hepta-7 Octa-8 Nona-9 Deca-10

For example, CO 2 would be monocarbon dioxygen. Or is it?

What type of ending do I use? Step 3: Use the ending –ide for the second element listed in the formula.

So this means that ……… CO 2 would be named carbon dioxide.

Practice Naming Covalent Compounds Covalent Compound Formula Name of Covalent Compound N2O5N2O5 CCl 4 CO SiO 2 ICl 3 P2O5P2O5

How would I write the formula if given the name? Use the symbols of the elements with their corresponding prefix numbers. Dinitrogen Trioxide would be __________. Use the symbols of the elements with their corresponding prefix numbers. Dinitrogen Trioxide would be __________.