Writing Formulas for Binary Ionic Compounds

• Binary Compounds:–Compounds composed of 2 elements.

• When writing names, the positive charge, the cation, must balance the negative charge of the anion.– Example: potassium chloride• K+ Cl-

• KCl

Naming Binary Ionic Compounds

• When naming binary compounds with metals that are not transition, just name metal and nonmetal.– Example:• CaCl2

–Calcium chloride• Li3N–Lithium nitride

Binary Compounds, continued• More examples:–Calcium Bromide• Ca2+ Br1-

• CaBr2

– Iron (III) Oxide• Fe3+ O2-

• Fe2O3

–Calcium Sulfide• Ca2+ S2-

• Ca2S2

• CaS

Naming Binary Ionic Compounds With Transition Metals

• CuO• Is it copper (I) or copper (II)?• Work Backwards:– 1. What is the charge of oxygen?• 2-

– 2. How many oxygen atoms are there?• 1

– 3. So your overall negative charge is what?• 2- (2- x 1)

Naming Binary Ionic Compounds, continued

–4. What charge must balance out a negative 2?• Positive 2

–5. How many atoms of copper are there?• 1

–6. So what is the charge of the copper atom?• 2+ (2+ ÷ 1)

Ternary Ionic Compounds

• Ternary Ionic Compounds:–A compound that contains atoms of three

different elements.• How would you write the formula for calcium

nitrate?–1. Write the symbol(s) and charge for each

part of the word.• Ca2+ NO3

1-

Ternary Ionic Compounds, continued

–2. Then cross and drop to balance your charges. (*If you need to cross and drop a number other than one next to a polyatomic ion, use parenthesis.)• Ca(NO3)2

–Write the symbol(s) and charge for each part of the word.•Mg2+ PO4

3-

•Mg3(PO4)2

MoleculesMolecules:

Smallest electrically neutral unit of a substance that still has the properties of the substance.Made of 2 or more nonmetals that act as a unit.Diatomics:

2 atomsI2, Br2, Cl2, F2, O2, N2, H2

Triatomics:3 atomsH2O, CO2, O3

Naming Binary Molecular Compounds

• Use the prefixes in Table 6.5. MEMORIZE THESE!!!– Mono- means 1– Di- means 2– Tri- means 3– Tetra- means 4– Penta- means 5– Hexa- means 6– Hepta- means 7– Octa- means 8– Nona- means 9– Deca- means 10

Naming Binary Molecular Compounds, continued

• *The only time you use the prefix mono- is when you have one of the second element. You NEVER use mono- on the first element.

• CO2– Carbon dioxide

• CO– Carbon monoxide

• PCl3– Phosphorous trichloride

• Cl2O8– Dichlorine octoxide

Naming Acids

• If Hydrogen is the first element in your compound, you have an acid.

• If it is a binary acid, 2 elements, use the prefix hydro- put the root word and then end in –ic.– Example: HCl• Hydrochloric

– Example: H3N• Hydronitric

Naming Acids, cont.

• If you have more than 2 elements, you have a polyatomic present in your acid.– All you change is the ending. • If the polyatomic normally ends in –ate, change the

ending to –ic.• If the polyatomic normally ends in –ite, change the

ending to –ous.

Naming Acids, cont.

• Example:– HNO3• H is present, so we know it’s an acid.• NO3 is nitrate• So, we have nitric acid

– HC2H3O2• H is present, so we know it’s an acid.• C2H3O2 is acetate• So, we have acetic acid

Naming Acids, continued

• Example:– HNO2• H is present so we know we have an acid.• NO2 is nitrite• So we have nitrous acid

– H3PO3• H is present so we know we have an acid.• PO3 is phosphite• So we have phosphorous acid

Is the first element in your compound an H?

Yes

No

You have an acid.Name it appropriately.

Are there more than2 elements?

Yes

No

You have a polyatomicpresent. What is it?Once you’ve found thatname as normal.

Do you have both ametal and a nonmetalpresent?

YesIs the metal atransition metal?

Yes

Find the chargeof the metal workingbackwards. Use roman numerals to identify the charge. Thenname the nonmetal with-ide at the end.

No

Name the metalas normal, then namethe nonmetal using-ide on the end.

No

It is a molecularcompound. Use prefixesto name it.

If you have a metal that is a transition metal, use roman numerals. If not just name it as normal.

The Flow Chart