Ionic Compounds

SNC2DI

Terms to Know

• Valence– The combining capacity of an element

• Valence shell– The outer electron shell of an atom, the

electrons in this shell are called valence electrons

Anions

Cl Cl

1-

• The chlorine atom now has a charge of -1 because it has gained an electron.

Cations

Na Na

1+

• The sodium atom is now an ion with a charge of +1 because it has lost an electron.

The Ionic Bond

• An ionic bond is when an electron from one atom is given to another atom and they are held together by strong electrostatic forces

• Ionic compounds are formed when ions form a compound

Formulas for Ionic Compounds

1. Write symbols with the metal first (metal+nonmetal

2. Write the combining capacity for each element over the symbol

3. Use “cross over” method and reduce numbers to lowest ratio

Al S3+ 2-

2 3 Mg S2+ 2-

2 2MgS

Naming Ionic Compounds

• Metal first

• non-metal second

• Change ending of non-metal to “ide”

magnesium + fluorine magnesium fluoride

aluminum + sulphur aluminum sulphide

Multivalent Ions

• Some metals form more than one type of ion

– E.g. Fe can be Fe2+ or Fe3+ and we use roman numerals to tell them apart

Formulas for Multivalent Ions• iron (II) + fluorine iron (II) fluoride

Fe F FeF2

• iron (III) + fluorine iron (III) fluoride

Fe F FeF3

2+ 1-

3+ 1-

Homework

• Read Chapter 5.8

• Q. 1-9 on P. 195

• Created by Carl Fusco