CHAPTER 9 Chemical Names And Formulas Test Review

Monoatomic Ions

Consist of a single atom with a positive or negative charge resulting from the loss of gain of one or more valence electrons, respectively.

Cations

Metallic elements that tend to lose valence electrons.

Ex. Lithium, Sodium, and Potassium tend to lose one electron to form cations.

Anions

Nonmetal elements tend to gain electrons to form anions, so the charge of a nonmetallic ion is negative.

How to determine the charge of any ion in Group 5A-7A

subtracting 8 from the group number.

Ions of transition metals

form more than one cation with different ionic charges

--> the charges of the cations of many transition metal ions must be determined from the number of electrons lost

How to name ions with more than one charge

1. Stock system

2. the Classical method

Stock Method

A Roman numeral in parentheses is placed after the name of the element to indicate the numerical value of the charge.

Ex. Fe2+ = Iron(II) ion VS Fe3+ = Iron(III) ion

Classical Method

uses a root word with different suffixes at the end of the word formed from its root name.

-ous vs -ic

-ous is used to name the cation with the lower of the two ionic charges

-ic is used with the higher of the two ionic charges

Ex. Fe2+ = Ferrous VS Fe3+ = Ferric

Polyatomic ions

ions composed of more than one atom

--> tightly bound groups of atoms that behave as a unit and carry a charge

Ex. sulfate anion = one sulfur atom + four oxygen atoms = 2- charge

Common ending for polyatomic ions

-ite or -ate

EXCEPTION: -ium (ammonium) or -ide (Cyanide or hydroxide)

-ite VS -ate

-ite one less oxygen atom than the -ate ending

--> does NOT tell you the actual number of oxygen atoms in the ion

--> all anions ending in -ite or -ate contain oxygen

Binary compound (9.2)

composed of two elements and can be either ionic (metal and nonmetal) or molecular (2+ nonmetals)

How to name binary ionic compounds

1. verify that the compound is a compound of a monatomic metallic cation and a monatomic nonmetallic anion

2. to name any binary ionic compound, place the cation name first, followed by the anion name

3. add any subscripts needed to balance the charges

How to determine which of two forms if applicable?

by working backwards in the criss cross method and balancing the charges

How to write binary ionic compounds

1. write the symbol of the cation and then the anion

2. add whatever superscripts are needed to balance the charges

-->charges must balance to 0 (easiest by using the criss cross method)

How to name compounds with polyatomic ions

state the cation first and then the anion just as in naming binary ionic compounds

Binary ionic compound

ions composed of the ions of two elements, a metal and a nonmetal

Binary molecular compound

molecules composed of two elements, but both elements are nonmetals and they are not ions (can not use ionic charges to write the formula or name it)

What does a prefix show? (9.3)

in the name of the binary molecular compound, it tell you how many atoms of an element are present in each molecule of the compound

Mono

Di

Tri

Tetra

Penta

Hecta

Hepta

Octa

Nona

Deca

1

2

3

4

5

6

7

8

9

10

The names of all binary molecular compounds end in?

-ide

Guidelines for naming binary molecular compounds

1. make sure that it is a binary molecular compound - two nonmetals

2. name the elements in the order listen in the formula

3. use the prefixes to indicate the number of each kind of atom

4. omit the prefix mono- when the formula contains only one atom of the first element in the name

5. the suffix of the name of the second is -ide

How to write formulas for binary molecular compounds (9.3)

use the prefixes in the name to tell you the subscript of each element in the formula. Then write the correct symbols for the two elements with the appropriate subscripts.

Acid (9.4)

ionic compounds that contain one or more hydrogen atoms and produces hydrogen ions (H+) when dissolved in water -- has various uses

What do acids always consist of?

that acids consist of an anion combined with as many hydrogen ions as are needed to make the molecule electrically neutral --> HnXn form where X=monatomic or polyatomic anion and n is the subscript indicating the number of hydrogen ions that are combined with the anion

How to name acids?

1. when the name of the anion (X) ends in -ide the acid name begins with the prefix hydro-. The stem of the anion has the suffix -ic and is followed by the word acid (ex. HCl= hydrochloric acid)

2. when the anion name ends in -ite the acid name is the stem of the anion with the suffix -ous followed by the word acid (ex. H2SO3 -- X=sulfite = sulfurous acid)

3. when the anion name ends in -ate the acid name is the stem of the anion with the suffix -ic followed by the word acid (ex. HNO3 -- X=nitrate -- = nitric acid)

Base

ionic compound that produces the hydroxide (OH-) ions when dissolved in water

How to name bases

bases are named in the same way as other ionic compounds - the name of the cation is followed by the name of the anion

How to write formulas for bases

write the symbol for the metal cation followed by the formula for the hydroxide ion. Balance the charges just as yiy would do for any ionic compound

Law of Definite Proportions (9.5)

In samples of any chemical compound the masses of the elements are always in the same proportion

Law of Multiple Proportions

Whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.

What two laws describe how chemical compounds form?

The law of definite proportion and the law of multiple proportion

What are 4 guidelines for writing the formulas of chemical compounds?

1)An -ide ending generally indicates a binary compound.

2) An -ite or -ate ending means a polyatomic ion that includes oxygen in the formula

3) Prefixes in a name generally indicate that the compound is molecular.

4) A Roman numeral after the name of a cation shows the ionic charge of the cation

Name these compounds.

A) CaCO₂

B) PbCrO₄

C) SnCr₂O₂

A)Calcium carbonate

B) Lead chromate

C)Tin chromate

Write formulas for these compounds.

A) tin(II) hydroxide

B) barium fluoride

A) SnOH₂

B) BaF₂

Identify the incorrect names or formulas.

a) calcium (II) oxide

b) aluminum oxide

c) Na₂C₂O₄

d) Mg(NH₄)₂

a) CaO

b) Al₂O₃

c) Sodium oxalate

d)Magnesium Ammonium