chapter 7: chemical nomenclature objectives name compounds given a formula write formulas given a...

Chapter 7: Chemical Nomenclature

OBJECTIVES

Name compounds given a formula Write formulas given a name Calculate moles, mass, and particles (CH 3) Find oxidation states of atoms Calculate molecular and empirical formulas Determine percent composition of a substance Calculate solution concentration (molarity)

A. The Formula

What’s in a name? Well, way more than you think

Systematic rules for naming Ionic and Covalent molecules governed by this organization. International Union of Pure and Applied Chemists.

_________IUPAC

C8H18 Al2(SO4)3

A. The Formula

C CH

H

H

HH C

H

HCH

HCH

HCH

HCH

HCH

HHC8H18

Al2(SO4)3 AlSO4

SO4

AlSO4

S O

O

O

O

B. Naming – Ionic Compounds

Formulas have a system:___________________cation followed by anion

What are cations?

What are anions?

+ charged; usually metals

- charged; usually nonmetals

How do you name cations?

Easy: name of the metal (or other element)

Al+3 =C+4 =

Aluminum cationCarbon cation

B. Naming - Ionic Compounds

How do you name anions?Drop last syllable (or 2) and add ‘-ide’ suffix

Anion Name

F-

Cl-

O-2

S-2

N-3

P-3

FluorideChlorideOxide

Sulfide

Nitride

Phosphide


NaCl

SrF2

Al2O3

Li3N

sodium chloride

strontium fluoride

aluminum oxide

lithium nitride

NAMING

Na Cl

F Sr F

AlAl

O OO

LiNLi

Li


Formula Writing – Rubidium sulfide

1. Write symbols Rb S

2. Write valence aboveRb S+1 -2

3. Ignore signs, criss-crossRb S1 2

4. Ignore 1’s and reducecharge should = 0

Rb2S

2Rb = +2; S = -2

Rb S Rb


rubidium selenide

cesium sulfide

radium silicide

FORMULAS

C. Naming – Polyatomic Ions

Some groups of atoms occur so often, they are named.

NH4

C2H3O2

orCH3COO

CN

HCO3

OH

NO3

NO2

PO4

Ammonium

Acetate

Cyanide

Bicarbonate

Hydroxide

Nitrate

Nitrite

Phosphate

+1

-1

-1

-1

-1

-1

-1

-2

-1

ClO3

ClO2

ClO

ClO4

MnO4

CrO4

CO3

SO4

SO3

Chlorate

Chlorite

Hypochlorite

Perchlorate

Permanganate

Chromate

Carbonate

Sulfate

Sulfite

-1

-1

-1

-1

-1

-2

-2

-2

-3

C. Naming – Polyatomic Ions

Rb2SO4

H2CO3

Rubidium Sulfate

Hydrogen Carbonate (AKA carbonic acid)

Calcium Cyanide

Ammonium Hydroxide

D. Naming – Transition metals, tin and lead

These elements have more than 1 valence. We name them using the STOCK SYSTEM. Use roman numerals to give the charge of the metal.Copper (II) sulfate

Tells you the charge

Cu SO4

+2 -2CuSO4

Copper (I) sulfate Cu SO4

+1 -2Cu2SO4

Zn = +2Ag =+1

Two Exceptions:

D. Naming – Transition metals, tin and lead

Pb(NO3)2

lead (III) nitrate

Sn(SO3)2

E. Naming covalent compounds

What is a covalent compound?

(NH4)2S

TiCl4

PtSi

MgBr2

Na2SO3

H2O

NO

P4O10

Cl2F2

N2O6

What’s the diff?

Covalent compounds are made of non metals with no polyatomic ions!

Ionic Covalent

D. Naming covalent compounds

Covalent compounds use a prefix system:

Mono

Di

Tri

Tetra

Penta

Hexa

Hepta

Octa

Nona

Deca

1 – used only for Oxygen when it’s last2

3

4

56

789

10

E. Naming covalent Compounds

N2O

OF3

N2O4

dinitrogen monoxide

oxygen trifluoride

dinitrogen tetroxide

NOT TETRAOXIDE

F. Common Names

Formula Common Name IUPAC Name

HCl

HNO3

H2SO4

HCH3COO

NH3

NaHCO3

CaCO3

NaClO

NaOH

SiO2

Hydrochloric acid

Nitric Acid

Sulfuric Acid

Acetic Acid

Battery Acid

Vinegar

AzaneAmmonia

Sodium bicarbonateBaking soda

Calcium carbonateChalk

Sodium hypochloriteBleach

Sodium hydroxideLye/Caustic Soda

Silicon dioxideSand/Quartz

G. Percent Composition

• the percentage by mass of each element in a compound

mass of element

% composition 100total mass


%Fe =

28 g

36 g 100 =78% Fe

%O =8.0 g

36 g 100 =22% O

• Find the percentage composition of a sample that is 28 g Fe and 8.0 g O.


100 =

%Cu =127.10 g Cu

159.17 g Cu2S 100 =

%S =32.07 g S

159.17 g Cu2S

79.852% Cu

20.15% S

• Find the % composition of Cu2S.

H. Empirical Formula

C2H6

CH3

reduce subscripts

• Smallest whole number ratio of atoms in a compound


1. If % given, assume you have 100g and the percents become masses.

2. Find moles of each element.3. Divide moles by the smallest

# to find subscripts.4. When necessary, multiply

subscripts by 2, 3, or 4 to get whole #’s.


• Find the empirical formula for a sample of 25.9% N and 74.1% O.

1.Assume 100g; therefore:

25.9 g N and 74.1 g O

2. Convert to moles:

25.9 gg

mol114.01

= 1.85 mol N

74.1 gg

mol116.00

= 4.63 mol O


• Find the empirical formula for a sample of 25.9% N and 74.1% O.

3. Divide by lowest number of moles:

1.85 mol N 4.63 mol O

1.85 mol1.85 mol= 1 N = 2.5 O

N1O2.5

4. Multiply to get whole numbers (by 2 here)

N2O5


Find the empirical formula of a compound if a sample is 3.65 g sodium, 2.54 g sulfur, and 3.81 g oxygen.

I. Molecular Formula

CH3

C2H6

empiricalformula

molecularformula

?

• “True Formula” - the actual number of atoms in a compound


• The empirical formula for ethylene is CH2. Find the molecular formula if the molecular mass is 28.1 g/mol?

28.1 g/mol

14.03 g/mol

= 2.00

empirical mass = 14.03 g/mol

(CH2)2 C2H4


1. Find the empirical formula.2. Find the empirical formula mass.3. Divide the molecular mass by the

empirical mass.4. Multiply each subscript by the

answer from step 3.

nmass EF

mass MF nEF

J. Molarity

_________ Moles of solute dissolved inLiters of solvent

(concentration)

MOLARITY

𝑀=𝑛𝐿

n = number of moles L = number of Liters

Unit is the MOLAR

How many moles of sodium fluoride are needed to make 400 ml of a 1.5 M solution What is the molarity of 35 g of calcium phosphate when dissolved in 800 ml of water?

chapter 7: chemical nomenclature objectives name compounds given a formula write formulas given a...

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