chapter 2: molecules, ions, and compounds

Chapter 2: Molecules, Ions, and Compounds

MACROSCOPIC SCALEElements combine to make compounds.

ATOMIC SCALEAtoms combine to make molecules, or

extended structures.

What we’ll cover…• Compound Formulas• Ions

– Monatomic– Polyatomic

• Ionic Compounds• Molecular Compounds• Other types of extended Structures

Compound Formulas

Examples:NaCl

CH3OH

(NH4)2SO4

Three Types of Compounds

Molecular Covalent Extended Covalent

Ionic

Types of Formulas

IONS

CationsFormed by losing

electrons.Have a positive

charge.Formed mainly

from metals.

IONS

CationsFormed by losing

electrons.Have a positive

charge.Formed mainly

from metals.

AnionsFormed by

gaining electrons.

Have a negative charge.

Formed mainly from nonmetals.

Monatomic Ions- Formed from single atoms

Naming IONS

CationsName of element + “ion”Na+ = sodium ionMg2+ = magnesium ion

Naming IONS

CationsName of element + “ion”Na+ = sodium ionMg2+ = magnesium ion

AnionsName of element with

–ide ending + “ion”Cl- = chloride ionO2- = oxide ion

Polyatomic Ions you need to know

Ionic Compound Formulas

Total cation charge = Total anion charge

Ex: Na+ and Cl- make ________

Ionic Compound Formulas

Total cation charge = Total anion charge

Ex: Na+ and Cl- make NaClMg2+ and Cl- make ________

Ionic Compound Formulas

Total cation charge = Total anion charge

Ex: Na+ and Cl- make NaClMg2+ and Cl- make MgCl2

NH4+ and SO4

2- make _________

Naming Ionic Compounds

Name = cation name + anion name

Ex:NaCl =NH4Br =

Molecular Compounds

Nonmetal + nonmetal gives molecular compound

Ex: C + O

S + O

C + H

Aside on gas prices…

Crude oil

Propane

Butane

Jet Fuel

Gasoline

Diesel/Heating

Longer molecules(asphalt/tar)

Predicting Molecular Compound Formulas

Naming Molecular Compounds

Binary Compounds form between 2 elements

Naming Molecular Compounds

Binary Compounds form with 2 elements

Element with highest group # named last, like it’s an anion.

Naming Molecular Compounds

Binary Compounds form with 2 elements

Element with highest group # named last, like it’s an anion.

Use prefixes to indicate numbers:2 = di3 = tri4 = tetra5 = penta

Network Solids

• Held together like a molecule• Large and extended