Intro to Chemical Bonding

Ch. 5 and Ch. 12

Unit Outline

Ch. 5- Nomenclature Naming chemical compounds and molecules

Ch. 12- Chemical Bonding Types of chemical bonds Stable electron configurations Lewis structures VSEPR Theory--molecular geometry

Nomenclature: Learning the Language

In the past, there was no system to name chemical compounds Common names used

Quicksilver Laughing Gas

Need a systematic way to name chemical compounds

Naming Binary Compounds Ionic compounds: a compound that contains ions Ion: A charged atom

Cation: Positively charged atom (lost 1 or more electrons)

Anion: Negatively charged atom (gained 1 or more electrons)

Metals usually form cations (lose electrons), nonmetals usually form anions (gain electrons)

Cations take the name of the parent element

Ex) Sodium metal Na(s) vs sodium ion Na+

Single atom anions: change element ending to -ide. The chlorine anion, Cl- is named the chloride

ion

How do you get the charge?

Look to the P.T.

For metals (not transition metals), Group # (or Group # - 10) is the positive charge

For nonmetals (18 - Group # is negative charge)

Transition metals can have multiple positive charges

Naming Type I ionic compounds Type I: Only one charge on the cation

Rules: 1. The cation is always listed first 2. The cation takes the name of the element The anion: take of ending of element and add

-ide.

Examples NaCl

KI

CaS

CsBr

sodium chloride

potassium iodide

calcium sulfide

cesium bromide

Naming Type II Ionic Compounds Type II: Cation can have multiple charges

Transition Metals

Consult ion list for charges Stock System** vs. Classic

Stock system = Name of element(charge as Roman numerals) Iron(III) = Fe3+

Classic = Latin or traditional name of element Ferric ion = Fe3+

Examples CuCl

HgO

MnO2

PbCl4

Copper(I) Chloride

Mercury(II) Oxide

Manganese(IV) Oxide

Lead(IV) Chloride

Naming Molecular (Non-metal) Compounds (Type III)

If all elements in the compound are nonmetals, use the following rules:

1. The first element in the formula is named first. (Full element name used)

2. 2nd element named as if it were a single atom anion

3. Prefixes denote the number of atoms present.

4. The prefix mono- is never used in naming the first element.

Examples

BF3

NO

N2O5

boron trifluoride

nitrogen monoxide

dinitrogen pentoxide

Polyatomic Ions

Polyatomic = more than one atom

Use same naming techniques as in ionic compounds

Examples

Na2SO4

Fe(NO3)3

NH4ClO3

Mn(OH)2

sodium sulfate

iron(III) nitrate

ammonium chlorate

manganese(II) hydroxide

Naming Acids

If the chemical formula starts with an H, it is an acid Look at what is after the H to name it If the anion ends in -ide

Hydro________ic acid HCl---chloride anion

Hydrochloric acid If the anion ends in -ate

_________ic acid HNO3-------nitrate anion

Nitric acid If the anion ends in -ite

_________ous acid HNO2-------nitrite anion

Nitrous acid

“-ate” something “-ic”y

In sp“-ite” of “-ous”

Writing Formulas from Names Ionic Compounds1. Write the symbol for each ion2. Balance charges with subscripts

If you get stuck, use the crisscross method

Example, write the formula for Iron(III) Oxide

Crisscross Method

Fe3+ O2-

Fe2O3Two Fe(III) have a charge of 6+ Three O2- have a charge of 6-

Make sure that the formula has subscripts with the least whole number ratio

You never put in a subscript of 1.

Writing formulas for molecular compounds

1. Write the element symbol

2. Prefix becomes subscript

Write the following chemical formulas potassium hydroxide sodium carbonate nitric acid cobalt(III) nitrate tetraphosphorus

hexoxide sulfur dioxide hydrosulfuric acid

KOH Na2CO3

HNO3

Co(NO3)3

P4O6

SO2

H2S