Chapter 5 Naming Compounds

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CHAPTER 5 NAMING COMPOUNDS

Background Information:

Counting Atoms

-  The formula tells the elements that make up a compound and the number of atoms of each element in the compound.

-  The number of atoms is indicated by a subscript.

•  Ex H2O

•  H= 2 O = 1

-  When a subscript appears outside of a set of parentheses, multiply everything inside the parentheses by the subscript.

•  Ex Mg3(PO4)2

•  Mg = 3 P = 2 O = 8

-  A coefficient tells how many whole molecules or elements are present. It is located before the formula or element and is multiplied through the whole formula.

•  Ex 4Mg3(PO4)2

•  Mg = 12 P = 8 O = 32

• 

-  If there is more than one instance of an element in a formula then count the number of atoms for each individually and add them together.

•  Ex Na3COOH

•  Na = 3 C = 1 O = 2 H = 1

Determining bond type-

A. Ionic bonds- bonds between a metal and a nonmetal – ex NaCl

B. Covalent bonds- bonds between two nonmetals - ex H2O

C. Metallic bonds-bonds between two atoms of same metal- ex Cu

D. Practice

1. Mg and F 2. Na and Br 7. H and H

3. O and Cl 4. Fe and Fe 8. H and Cl

5. Zn and Zn 6. O and F

STOP HERE and COMPLETE HOMEWORK

Writing ionic formulas

1.  criss cross method is a easy way to determine the formula BUT you must

also understand why this method works!!!!

2. Guess what?

a. in order to complete the criss cross method you need to

know the oxidation number of the element

b. Practice

i.) Na + Cl = Na CL

ii) Mg + F = Mg F

iii) Ca + O = Ca O

iv) N + Li = Li N

c. why is lithium written before nitrogen?

The positive ion is called a cation and is always written first

The negative ion is called an anion and is written second.

** in other words the Cation (usually the metal) is ALWAYS written first

C. Transition metals work a little differently

a. how many valence electrons do transition metals have?

*because they vary we need to figure out and then write down their oxidation number

Recall – we figure out the oxidation number of a transition metal by looking at who they are paired with

***helpful hint – the TOTAL charge must always = 0

b. sometimes we use use roman numerals or numbers to do this

I = one II = two III = three IV = four

c. practice

i.) Cr (+4) + O = Cr O

c. What is the charge/oxidation number on Iron?

ii) Fe ( ) + O = Fe2O3

iii) Zn (+2) + Cl = Zn Cl

what is the charge/oxidation number on nickel?

iv) Ni ( ) + S = NiS

v) Mn ( ) + O = MnO2

Rules for Naming Ionic Compounds

A. Binary Ionic Compounds (metals from Group 1 or 2) (ex: CaCl2)

1. Name the metal

2. Name the nonmetal-

a. change ending to –ide

(calcium chloride)

3. Practice:

a. KCl

b. LiF

c. Na2O

B. Binary Ionic Compounds (transition metals) (ex: Fe2O3)

1. Name the metal

2. Transition metals have more than one + charge (ex: iron can have +2 or +3)

a. determine the charge of nonmetal

Fe O

b. Figure out the - charge on “non-metal” side, then set the metal equal to the + charge

3. After the name of metal, write charge in roman numerals. (put in ( ) ).

Fe +3 = iron (III)

4. Name the nonmetal. Change ending to –ide

5. Fe2O3 = Iron(III)oxide

5. Practice:

a. CuO b. ZnCl2

Mixed practice:

1. Na20

2. FeF3

3. BaI2

4. AgS

Naming covalent Compounds

1. Use same ending as most ionic compounds…….ide

1. Covalent Bonding requires Prefixes

*you cannot start any covalent compound with the word mono

PREFIX / NUMBER
Mono / 1
Di / 2
Tri / 3
Tetra / 4
Penta / 5
Hexa / 6
Hepta / 7
Octa / 8
Nona / 9
Deca / 10

a. prefixes tell you how many of each atom there are in the compound

2. Examples

a. H2O b. BF3 c. N2O4

3. Practice

a. SiO2 b. CO2

c. CO d. P2O5

C. Naming Compounds with polyatomics …… Poly = many

1. Certain ions are made of covalently bonded atoms that tend to stay together and act as if they were single atoms

2. therefore bonds WITHIN polyatomic ions = covalent (talk later)

3. but they usually form ionic bonds with other atoms

Some of the common polyatomics and their charge

Ammonium / NH4 +1
Acetate / C2H3O2 -1
Chlorate / ClO3 -1
Hydrogen carbonate / HCO3 -1
Hydroxide / OH -1
Nitrite / NO2 -1
Nitrate / NO3 -1
Carbonate / CO3 -2
Sulfate / SO4 -2
Sulfite / SO3 -2
Phosphate / PO4 -3

4. Differert types of ployatomic compounds

a. (metal + polyatomic)

step one…..Name metal

-use roman numerals for transitions

step 2….. Name the poly.

-DO NOT CHANGE ENDING

b. (poly. + nonmetal)

step 1 …..Name poly. (no ending changes)

step 2…..Name nonmetal. change ending to –ide

c. (poly. + poly)

step 1…..Name the 1st poly.

Step 2…..Name the 2nd poly. -no ending changes

4. Practice:

a. NaHCO3

b. Mg(OH2)

c. Na2SO4

d. K2CO3

e Ca(ClO3)2

f. Sn(CH3COO)2

g. Ca(OH)2

h. K2CO3

i. MgSO4

j. CuSO4

k. Pb(OH)2

l. CuCO3

Naming Acids

When dissolved in water, certain molecules produce H+ ions. These substances are called acids. An acid can be viewed as a molecule with one or more H+ ions attached to an anion (negatively charged atom).

If the anion DOES NOT CONTAIN OXYGEN, the acid is named with the prefix “hydro” and the siffix “ic” is attached to the root name for the element

EXAMPLE HCl dissolved in water = no oxygen therefore…….HYDROchlorIC acid

HCN disssolved in water = hydrocyanic acid

H2S dissolved in water = hydrosulfuric acid

If the anion DOES CONTAIN OXYGEN, the acid name is formed from the root name of the central element of the anion with a suffix of “ic” or “ous”. When the anion name ends in ate the suffix “ic” is used.

Example H2SO4 dissolved in water = the anion is sulfate so…….sulfuric acid

H3PO4 dissolved in water = the anion is phosphate so…. phosphoric acid

HC2H3O4 = anion is acetate so…………acetic acid

Example: H2SO3 = anion is sulfite so …….. sulfurous acid

HNO2 = anion is nitrite so……. Nitrous acid