Warm Up:

1. How many moles are contained in 6.0 g of carbon?

2. When two chemicals are mixed together in a beaker that is sitting in an ice water bath, the ice in the water melts as the chemicals react. Is the reaction exothermic or endothermic? Explain your reasoning.

Ions and Ionic Bonding• One way for atoms to reach stability is by either losing or gaining electrons.

• When this occurs an ion is formed.

• Ion – an atom that has a charge.

• Occurs when the number of protons is unequal to the number of electrons.

Cations• Whenever atoms lose electrons they form

cations.

• Cations are positively charged atoms.

• Metals tend to form cations.

• Example:

– Sodium

Anions• Whenever atoms gain electrons they form

anions.

• Anions are negatively charged atoms.

• Nonmetals tend to form anions.

• Example:– Chlorine (Cl)

We can use the periodic table to predict

the type of ion an atom will form.

Group Number Type of Ion Formed

1 +1

2 +2

13 +3

15 -3

16 -2

17 -1

What Do You Think?

1. What charge would Lithium make?

2. What charge would sulfur make?

3. Neon?

Ionic Bonding• Ionic bonding involves the transfer of

electrons from one atom to another.

• We can use electron dots to show how ionic bonds are formed.

• Example: – Na and Cl

• Opposite charges serve as the glue that holds

the atoms together in the bond.

• Ionic bonds are extremely strong chemical bonds.

• Ionic bonds usually involve a combination of a metal with a nonmetal.

– By definition, an ionic bond is made when the electronegativity difference between atoms is greater than 1.7

Illustrating Ionic Bonding in Compounds• Use electron dots to demonstrate how

calcium (Ca) and bromine (Br) form a stable compound by ionic bonding. Give the chemical formula for the compound formed.

Polyatomic Ions can act as anions!

•Group of covalently bonded atoms that has a charge. (a charged molecule)

•Example: SO4-2 (sulfate ion)

Writing Formulas and Naming Chemical Compounds

• There are two types of chemical compounds:

– ionic compounds– covalent (molecular) compounds

• Ionic Compounds are composed of a cation and an anion.

– cations – positively charged ion (metals)

– anions – negatively charged ion (nonmetals)

Monoatomic Ions• Cations

– For monatomic cations, the name of the ion is the name of the element.

– examples:

Na+ = sodium ion

Mg2+ = magnesium ion

Al3+ = aluminum ion

– Some metals are able to form more than one stable ion (polyvalent)

• usually transition elements• example: copper • forms Cu2+ and Cu+

• use Roman numerals to distinguish charge

• copper (II) and copper (I)

• Anions– Monoatomic anions are named by dropping the

ending of the element and replacing with the suffix “-ide”.

– examples:

Cl- = chloride ion

O2- = oxide ion

N3- = nitride ion

Naming Binary Ionic Compounds

• The nomenclature, or naming system, or binary ionic compounds involves combining the names of the compound’s positive and negative ions.

• The name of the cation is given first, followed by the name of the anion:– example: Al2O3 — aluminum oxide

Independent practice

1. What is the formula and name for Sodium and Oxygen?

2. What would the formula and name be for potassium and sulfur?

The Stock System of Nomenclature

Write the formula and give the name for the compound formed by the ions Cr3+ and F–.

Independent Practice

1. Give the formula for Chromium (II) Fluoride.

2. What is the name of Fe2O3?

Compounds Containing Polyatomic Ions

• Many common polyatomic ions are negatively charged and oxyanions— polyatomic ions that contain oxygen.

• Some elements can combine with oxygen to form more than one type of oxyanion.– example: nitrogen can form or .−

3NO

nitrate nitrite

• The name of the ion with the greater number of oxygen atoms ends in -ate. The name of the ion with the smaller number of oxygen atoms ends in -ite.

2NO−

3NO−2NO−

• Some elements can form more than two types of oxyanions.– example: chlorine can form , ,

or .

• In this case, an anion that has one fewer oxygen atom than the -ite anion has is given the prefix hypo-.

• An anion that has one more oxygen atom than the -ate anion has is given the prefix per-.

hypochlorite chlorite chlorate perchlorate

ClO−2ClO−

3ClO−4ClO−

ClO−2ClO−

3ClO−

4ClO−

Give the formula for…

1. Potassium Chlorate

2. Hydrogen Sulfite

3. Tin(IV) sulfate.

Closure

• What is one thing you learned today?

• What is one thing we need more practice on?