CHAPTER 7

CHEMICAL FORMULAS AND CHEMICAL COMPOUNDS

7.1

CHEMICAL NAMES AND FORMULAS

IONIC COMPOUNDS

7.1 NOTES

A compound, whether ionically or covalently bonded, always has the same ratio of moles of atoms. (Law of Definite Proportion)

7.1 NOTES

An ionic compound is composed of ions bonded together.

It could be 2 monatomic ions 2 polyatomic ions 1 monatomic and 1 polyatomic

7.1 NOTES

What is the difference between a monatomic and a polyatomic ion?

7.1 NOTES

Monatomic ions contain one atom and polyatomic ions contain 2 or more atoms.

The charge for monatomic ions is based on the number of electrons they lose or gain to have a filled valence shell.

Some common ones are listed on p. 221.

7.1 NOTES

The charge for monatomic ions is based on the number of electrons they lose or gain to have a filled valence shell.

Na Na1+

Mg Mg2+

Cl Cl1-

O O2-

7.1 NOTES

Most transition metals can have more than one charge, but there are two elements in the transition metals that always form the same charged ion.

Ag Ag1+

Zn Zn2+

7.1 NOTES

Polyatomic ions are groups of atoms that bond covalently, but have an overall charge, so they act as an ion when bonding.

Some of the common ones are listed on p. 226.

7.1 NOTES

Oxyanions contain oxygen in varying numbers.

ClO1- is hypochlorite

ClO21- is chlorite

ClO31- is chlorate

ClO41- is perchlorate

How do you remember all of these?

7.1 NOTES

Nick the Camel ate Clams for Supper in Phoenix.

The underlined letter is the element in the ion.

The number of consonants is the number of oxygens.

The number of vowels is the charge.

The names all end in –ate.

NO31-

CO32-

ClO31-

SO42-

PO43-

7.1 NOTES

Rules for naming ionic compounds:

7.1 NOTES

Rules for naming ionic compounds:

1. Cation always comes first

If an element forms more than one type of ion, that must be noted using a Roman numeral for the charge.

This most often happens in the transition metals.

7.1 NOTES

Rules for naming ionic compounds:

1. Cation always comes first

If an element forms more than one type of ion, that must be noted.

Cu Cu1+ or Cu2+

7.1 NOTES

Rules for naming ionic compounds:

1. Cation always comes first

If an element forms more than one type of ion, that must be noted.

Cu Cu1+ or Cu2+

copper (I) copper (II)

The common transition metals that we will use are listed on

the pink sheet.

7.1 NOTES

Rules for naming ionic compounds:

1. Cation always comes first

If an element forms more than one type of ion, that must be noted.

2. Anion always comes second.

If it is a monatomic ion (single element) change the ending of the element to –ide.

7.1 NOTES

Rules for naming ionic compounds:

1. Cation always comes first

If an element forms more than one type of ion, that must be noted.

2. Anion always comes second.

If it is a monatomic ion (single element) change the ending of the element to –ide.

If it is a polyatomic ion use the given name.

7.1 NOTES

Rules for writing formulas for ionic compounds:

1. Cation always comes first

If a Roman numeral is present, it represents the charge on the cation.

7.1 NOTES

Rules for writing formulas for ionic compounds:

1. Cation always comes first

If a Roman numeral is present, it represents the charge on the cation.

2. Anion always comes second.

7.1 NOTES

Rules for writing formulas for ionic compounds:

1. Cation always comes first

If a Roman numeral is present, it represents the charge on the cation.

2. Anion always comes second.

3. Balance the charges so that the overall charge is zero.

7.1 NOTES

Rules for writing formulas for ionic compounds:

1. Cation always comes first

If a Roman numeral is present, it represents the charge on the cation.

2. Anion always comes second.

3. Balance the charges so that the overall charge is zero.

4. If parentheses are needed to multiply polyatomic ions, use them.

7.1 NOTES

Rules for writing formulas for ionic compounds:

1. Cation always comes first

If a Roman numeral is present, it represents the charge on the cation.

2. Anion always comes second.

3. Balance the charges so that the overall charge is zero.

4. If parentheses are needed to multiply polyatomic ions, use them.

5. Check to make sure the lowest ratio of subscripts are used.

7.1 NOTES

ATOMS INVOLVED CATION ANION FORMULA NAME

magnesium

oxygen

zinc bromine

ammonium

sulfur

copper (II) fluorine

7.1 NOTES

CATION ANION FORMULA NAME

Ca(NO3)2

FeCl3

Ag2SO4

(NH4)3PO4

7.1 NOTES

CATION ANION FORMULA NAME

magnesium sulfate

lead (IV) oxide

cobalt (II) hydroxide

calcium acetate

7.1 NOTES

IONS QUIZ Worth 50 points Combined with “Ions Cubed” for a lab grade Memorize p. 221 and p. 226 You will have a periodic table without names

on it (only symbols) You will not have the pink sheet

MOLECULAR COMPOUNDS

7.1 NOTES

Molecular compounds, because they can be bonded more than one way, have different rules.

7.1 NOTES

Molecular compounds, because they can be bonded more than one way have different rules.

For instance:

CO and CO2

There are different ways of naming these, and because they are not ions, Roman numerals aren’t used.

Although there is a push to use Roman numerals (Stock system) for these as well.

7.1 NOTES

Rules for naming molecular compounds.

1. The element in the lower number group goes first, or if in the same group, the element with the higher period number goes first. This element uses a prefix to denote the number of atoms, but never uses “mono-”. The English name is used.

7.1 NOTES

Rules for naming molecular compounds.

1. The element in the lower number group goes first, or if in the same group, the element with the higher period number goes first. This element uses a prefix to denote the number of atoms, but never uses “mono-”. The English name is used.

2. The second element always uses a prefix also to denote the number of atoms. A root word of the element is used along with the ending “–ide”.

7.1 NOTES

Rules for naming molecular compounds.

1. The element in the lower number group goes first, or if in the same group, the element with the higher period number goes first. This element uses a prefix to denote the number of atoms, but never uses “mono-”. The English name is used.

2. The second element uses a prefix also to denote the number of atoms. A root word of the element is used along with the ending “–ide”.

3. If there are multiple vowels in between the prefix and the root word, one of them is often dropped.

7.1 NOTES

Rules for naming molecular compounds.

1. The element in the lower number group goes first, or if in the same group, the element with the higher period number goes first. This element uses a prefix to denote the number of atoms, but never uses “mono-”. The English name is used.

2. The second element uses a prefix also to denote the number of atoms. A root word of the element is used along with the ending “–ide”.

3. If there are multiple vowels in between the prefix and the root word, one of them is often dropped.

4. When metalloids bond with nonmetals (usually the case), this system of naming is used.

7.1 NOTES

FORMULA NAME

P4O6

S2Cl2

AsCl5

ClF3

OF2

7.1 NOTES

FORMULA NAME

Phosphorous tribromide

Nitrogen monoxide

Trisulfur nonoxide

Iodine pentachloride

Tetraarsenic decoxide

7.1 NOTES

Why are acids so unique?

7.1 NOTES

An acid is a covalently bonded molecule which forms ions.

HCl + H2O H3O1+ + Cl1-

7.1 NOTES

Rules for naming acids

1. The anion which forms the basis of the acid is used for the name.

2. If it is a binary acid (hydrogen plus one other element) the name is hydro_________ic acid.

3. If it is an oxygen acid (hydrogen, oxygen plus one other element) the name depends on the number of oxygen atoms present.

per__________ic acid (anion is per_____ate) HClO4

__________ic acid (anion is _____ate) HClO3

__________ous acid (anion is _____ite) HClO2

hypo_________ous acid (anion is hypo____ite) HClO

7.1 NOTES

NAME FORMULA ANION ANION NAME

Sulfuric acid

Perchloric acid

Hydrofluric acid

7.1 NOTES

NAME FORMULA ANION ANION NAME

HBrO4

H2CO3

H2S

HNO3

7.1 NOTES

NAME FORMULA ANION ANION NAME

Sulfite

Nitrite

Iodide

Acetate