Naming CompoundsVideo Notes

In this lesson, you will:

• Name both ionic and molecular compounds when given the chemical formula, including some hydrocarbons.

Binary Ionic Compounds

• Consist of only 2 elements. A metal and a non-metal

• Name the positive ion first (cation)- usually this is the metal.

• Name the negative ion (the anion), changing the ending to –ide. (this is typically the non-metal.)

Binary Ionic Compounds

• When metals that can form more than one type of ion are in a compound, use a Roman numeral in parentheses after the name of the metal to show the charge.

• This is called the Stock system of nomenclature (instead of using prefixes)

Some Examples

NaCl• Cation- Sodium• Anion- Chlorine (chloride when you change the

name)• So the name is sodium chloride.

MgO• Cation- Magnesium• Anion- Oxide• So the name is magnesium oxide.

The Stock System

• Example:• Copper Sulfide (Cu2S)- First you look on the

periodic table or a charge chart to determine the charge on the Sulfur ion (remember the name changes when it is an ion to –ide)

• Sulfide ion has a charge of 2-. • On the copper, take the overall charge and divide

by the number of ions to get the charge for each ion. In this situation, there is 1+ for each Cu ion. You will write copper(I)sulfide. The roman numeral I just tells us it is the 1+ ion for copper.

The Stock System

• SnCl4 Chlorine has a 1- charge (times 4 ions for a total of 4-), so the tin (Sn) must have a 4+ charge.

• Tin(IV)chloride is how you would write the name.

Ternary Compounds

• Made up of 3 elements• Name the cation then name the

polyatomic anion without changing the ending to “ide”

Naming Ternary Compounds

Na2SO4 Sodium Sulfate

FeCrO4 (hint: Fe is one of those metals that can have more than one charge)

Iron(II)Chromate Since the Chromate ion has a 2- charge, the iron must have a 2+ charge… Hence the (II).

You will get used to certain polyatomic ions so you won’t have to look them up each time. Like SO4 is sulfate.

Remember

Ionic CompoundComposed of a cation and an anion

Transfer electrons to form a ionic compound

Molecular CompoundComposed of non-metals

Rule of Thumb

Ionic or Molecular

If the first element is a metal, use the rules for naming an ionic compound

If the elements are all non-metals, use the rules for naming a molecular compound

(exception: When the cation in an ionic compound is

a non metal but is the polyatomic ammonium ion NH4.

Naming Molecular compounds

1. The elements are named in the order they appear in the formula.

2. Prefixes are used to denote the number of atoms of each element in the molecule. An exception is that the first element named is given a prefix only if there is more than one atom of that element in the molecule.

3. The “o” or “a” at the end of a prefix is dropped when the word following the prefix begins with a vowel.

4. The last element’s ending is changed to “-ide”

Molecular compound practice

• ICl3 Iodine and Chlorine– both are non metals – Iodine Trichloride

• As2O5

– Both are non metals– There are 2 ions in the Ar, so you will use a

prefix in the first element’s name.– Diarsenic pentoxide

Naming Hydrocarbons

Alkane- CnH2n+2

Alkene- CnH2n

So review….C4H10… Alkane or Alkene?Alkane….so the suffix is “ane”…Prefix- 4 so it is Butane

Another?...C2H4…. Alkene so the suffix is “ene”The prefix- 2 so it is Ethene

Chemistry Quiz

CR1. Mendeleev arranged the elements by increasing atomic -?-.

a. Numberb. Massc. Theory

Chemistry Quiz

CR2. What is the electron distribution of carbon which has and atomic number of six?

a. 1s12s13s13p3

b. 1s22s23s2

c. 1s22s22p2

d. 1s22s23s2

Chemistry Quiz

1. A molecular compound is composed of metals sharing electrons

a. Trueb. False

Chemistry Quiz

2. What is the name of the compound represented by the chemical formula OF2?

a. Oxygen difluorideb. Monoxygen difluoridec. Oxygen bifluorided. Monoxygen bifluoride

Chemistry Quiz

3. What formula Fe2O3 represents the compound ______.

a. Iron oxideb. Iron (II) oxidec. Di-iron trioxided. iron(III) oxide

Chemistry Quiz

4. When naming an alkane, the prefix denoting one carbon in the compound is

a. meth-b. Eth-c. Pent-d. But-

Chemistry Quiz

5. In binary ionic compounds, the ending of the anion is –ide.

a. Trueb. False