Properties of Ionic CompoundsForming NaCl from Na and Cl2

Properties of Ionic CompoundsForming NaCl from Na and Cl2

• A metal atom can transfer an electron to a nonmetal.

• The resulting cation and anion are attracted to each other by electrostatic forces.

The Octet Rule – Ionic Compounds

Ionic compounds tend to form so that each atom, by gaining or losing electrons, has an electron arrangement like that of a noble gas.

CATION + ANION --->

COMPOUND

CATION + ANION --->

COMPOUND

A neutral compound requires

equal number of + and - charges.

A neutral compound requires

equal number of + and - charges.

COMPOUNDS FORMED

FROM IONS

COMPOUNDS FORMED

FROM IONSNa+ + Cl- --> NaCl

Electron Dot Notation

Predicting Ionic Charges

Group 1:Lose 1 electron to form 1+ ions

H+ Li+ Na+ K+

Predicting Ionic Charges

Group 2:Loses 2 electrons to form 2+ ions

Be2+ Mg2+ Ca2+ Sr2+ Ba2+

Predicting Ionic ChargesGroup 13: Loses 3 electrons to form 3+ ions

B3+ Al3+ Ga3+

Predicting Ionic ChargesGroup 14: Loses 4 electrons or gains 4 electrons

Caution! C22- and C4-

are both called carbide

Predicting Ionic ChargesGroup 15: Gains 3 electrons to form 3- ions

N3-

P3-

As3-

Nitride

Phosphide

Arsenide

Predicting Ionic ChargesGroup 16: Gains 2 electrons to form 2- ions

O2-

S2-

Se2-

Oxide

Sulfide

Selenide

Predicting Ionic ChargesGroup 17: Gains 1 electron to form 1- ions

F1-

Cl1-

Br1-Fluoride

Chloride

Bromide

I1- Iodide

Predicting Ionic ChargesGroup 18: Stable Noble gases do not form ions!

Predicting Ionic ChargesGroups 3 - 12:

Many transition elements have more than one possible oxidation state.Iron(II) = Fe2+ Iron(III) = Fe3+

Predicting Ionic ChargesGroups 3 - 12:

Some transition elements have only one possible oxidation state.

Zinc = Zn2+ Silver = Ag+

Predicting Charges on Monatomic IonsKNOW THESE !!!!

+1 +2 -3 -2 -1 0

Be2+

Writing Ionic Compound Formulas

Example: Iron(III) chloride

1. Write the formulas for the cation and anion, including CHARGES!

Fe3+Cl-2. Check to see if charges are balanced.

3. Balance charges , if necessary, using subscripts.

Not balanced!

3

Writing Ionic Compound Formulas

Example: Aluminum sulfide

1. Write the formulas for the cation and anion, including CHARGES!

Al3+ S2-2. Check to see if charges are balanced.

3. Balance charges , if necessary, using subscripts. Not

balanced!

2 3

Formulas of Ionic Compounds

Formulas of ionic compounds are determined from the charges on the ions

atoms ions

–Na + F : Na+ : F : NaF

sodium + fluorine sodium fluoride formula

Charge balance: 1+ 1- = 0

Some Ionic CompoundsSome Ionic Compounds

Mg2+ + N-3 ---->Mg3N2

magnesium nitrideSn4+ + O2- ----> SnO2

Tin (IV) oxide

calcium fluoride

Ca2+ + 2 F- CaF2

Monatomic Ions

Learning Check

Write the correct formula for the compounds containing the following ions:1. Na+, S2-

a) NaS b) Na2S c) NaS2

2. Al3+, Cl-

a) AlCl3 b) AlCl c) Al3Cl

3. Mg2+, N3-

a) MgN b) Mg2N3 c) Mg3N2

Solution

1. Na+, S2-

b) Na2S

2. Al3+, Cl-

a) AlCl3

3. Mg2+, N3-

c) Mg3N2