ChemCatalyst How would you make an aluminum ion

from an aluminum atom? What type of ion is this?

How would you make an oxide ion from an oxygen atom? What type of ion is this?

ChemCatalyst How would you make an aluminum ion from

an aluminum atom? What type of ion is this? Al+3 so remove 3 electrons Cation

How would you make an oxide ion from an oxygen atom? What type of ion is this? O-2 so add 2 electrons Anion

(Ion)derstand Ions

Ions Atoms are neutral

Equal number of protons and electrons

Atoms can become charged by gaining or losing an electron Called ions

Ions are indicated with a (+) or (-) sign Cations are positive Anions are negative

Why Gain or Lose?

Noble gases are unreactive

Most stable elements

Atoms of elements gain or lose electrons to become more like noble gases

Cations and Anions

Two Types of Cations and Anions

Monatomic Ions Ions containing one type of atom

• Ca2+ O2-

Polyatomic Ions Ions containing two or more types of

atoms

• NH41+ NO3

1-

Metals (left side of table)

Form cations

Lose electrons to get to the noble gases

Only works if the charge is +3 or less

Cation Formation

Na Na+e-

Naming Metal Cations Metal name + “ion”

For transition metals use systematic name

Metal name followed by charge written as a Roman numeral in paranthesis + “ion”

Naming Metal Cations Example

Write the systematic name for Fe+2 and Fe+3.

• Fe+2

• Iron(II) ion

• Fe+3

• Iron(III) ion

Nonmetals (right side of table)

Form anions

Gain electrons to get to the noble gases

Only works if the charge is -3 or less

Anion Formation

Cl-e-Cl

Naming Nonmetal Anions Nonmetal root ending in “ide” + “ion”

Example What is the name of the hydrogen

anion?• Hydride ion

What is the name of the nitrogen anion?• Nitride ion

Making Salt What is the formula for table salt?

What does Na need to do to become like a noble gas?

• Lose an electron

What does Cl need to do to become like a noble gas?

Gain an electron

Making Salt

But Why?! Ions form so each atom can become

like a noble gas When the cation and anion form, we get

two charged ions

Opposite charges attract Electrostatic force Ionic bond = Ionic compound

Metal + nonmetal Left side + right side

Trends in the Table Alkali Metals

Form +1 ions

Alkaline Earth Metals Form +2 ions

Transition Metals Can have multiple charges

Halogens Form -1 ions

Noble Gases Do not form ions

Chemical Formulas

Set of symbols that represent a compound Contains two or more elements chemically

combined

How does a chemical formula differ from a chemical symbol? Formula is for a substance containing

several elements Symbol is for a single element

Symbols vs. Formulas

What do Na and O represent? The chemical symbols for sodium and

oxygen What does Na2O represent?

The chemical formula for sodium oxide What does the 2 stand for?

• 2 sodium ions

Why do we put subscripts? To count atoms/balance charges

Naming Formulas

Ionic compounds What is the name of AlBr3?

• No transition metal Step 1: Write the cation name

• Cation is Al+3 = aluminum ion Step 2: Write the anion name with the

ending –ide• Anion is Br- = bromide

Aluminum bromide

Naming Formulas

Ionic compounds What is the name of NiS?

• Nickel is a transition metal

Step 1: Write the cation name• Cation is Ni+2

Step 2: Write the charge/ roman numeral of the cation in parenthesis

• Nickel(II)

Step 3: Write the anion name with the ending –ide• Anion is S-2 = Sulfide

Nickel(II) sulfide

Writing Formulas from names

What is the formula for potassium nitride? K = alkali metal = not a transition metal

• Cation is K+

• Anion is N-3

K3N

What is the formula of chromium (III) chloride? Roman numerals = transition metal, so charge is +3

• Cation is Cr+3

• Anion is Cl-

CrCl3

Naming Molecular Formulas Molecular compounds

2 nonmetals (right side + right side)

Uses prefixes

• Do not write mono for first nonmetal

Second nonmetal has -ide ending

Prefixes

Number of Atoms Prefix

1 Mono

2 Di

3 Tri

4 Tetra

5 Penta

6 Hexa

Examples

What is the name of PCl3? 1 P = phosphorus 3 Cl = trichloride Phosphorus trichloride

What is the formula for dihydrogen monoxide? Di = 2 H Mon = 1 O H2O