Pre-IB Chemistry Unit 6: Ionic Compounds

Formed when a cation and an anion come together

Ionic compounds

These are also known as

Salts

The electrostatic force that holds oppositely charged particles together

Ionic Bond

Properties of Ionic Compounds

- Form crystals
- Hard
- Brittle (fall apart when squeeze)
- High melting and boiling points (in order to break ionic bonds)
- Conduct electricity when dissolved and when molten (melted)
- Good insulators as a solid

In an ionic compound, large numbers of _____________________ exist together.

Cations and Anions

The strong attractions between the cations and anions in an ionic compound result in the formation of a

Crystal lattice

(Formation of ions)

Certain atoms acquire the stable outer electron configuration by losing electrons. This positive ion is called a

Cation

A cation usually tends to be form by

Metals

Certain atoms acquire the stable outer electron configuration by gaining electrons. This negative ion is called a

Anion

An anion usually tends to be form by

Nonmetals

What's a crystal lattice?

Is a three-dimensional geometric arrangement of particles where each cation is surrounded by anions and vice-versa

Ionic compounds are hard and brittle due to

the strong attractive forces that hold the ions in place

When an external force is applied the crystal breaks apart because

the force repositions the like-charged ions next to each other.

Ionic Compounds have high melting and boiling points because ionic bonds are relatively ______________ and require a large amount of energy to be ______________.

strong; broken apart

Ionic compounds can conduct electricity ONLY when

melted or dissolved in solution

This is possible because the ions are now free to ___________________________

move and conduct electricity

In the _______________ the ions are locked in fixed positions so ionic solids do not conduct electricity.

solid state

(Naming Binary Compounds)

Binary ionic compounds are composed of a

metal + nonmetal

The ______________ will be named first

cation

The cation is the

metal

The ______________ will be named second

anion

The anion is the

nonmetal

The name of the nonmetal (anion) ends with

-ide

Examples of -ide endings

- Nitride
- Sulfide
- Phosphide

Examples of metal + nonmetal compounds

BaS - Barium sulfide
Mg3P2 - Magnesium phosphide
NaF - Sodium fluoride

(Naming Binary Compounds)

When a binary ionic compound is composed of a transition metal + nonmetal, one should include the

charge of the transition metal

The charges of the transition metals are written in

roman numerals

The charges can go from ____________________

1 (I) to 6 (VI)

Examples of transition metal + nonmetal compounds

Fe2O3 - Iron (III) oxide
Cu2S - Copper (I) sulfide
Mn3N2 - Manganese (II) nitride

When metals come together with nonmetals, the number of electrons lost by the metal must equal the number of electrons gained by the nonmetal. This means that

compounds are neutral, they have a neutral charge

(Writing Formulas for Binary Ionic Compounds)

When writing formulas for BIC the positive charge of the __________ must __________ with the negative charge of the ___________.

cation; balance; anion

The net ionic charge of the formula must be

zero

Examples

K+ and Cl- make KCL

Mg2+ and O2- make MgO

Mn2+ and N3- make Mn3N2

Polyatomic Ions

Ions that are made of more than one atom

Ammonium

NH4+

Acetate

C2H3O2-

Cyanide

CN-

Hydroxide

OH-

Perchlorate

ClO4-

Permanganate

MnO4-

Carbonate

CO3 2-

Chromate

CrO4 2-

Nitrate

NO3-

Nitrite

NO2-

Sulfate

SO4 2-

Sulfite

SO3 2-

Phosphate

PO4 3-

Phosphite

PO3 3-

Naming Ternary Ionic Compounds: Steps

1. Recognize the polyatomic ion
2. Name the cation then the anion
3. If cation is a transition metal, you must use Roman Numerals to identify the charge

Example: KCN

1. CN-
2. Cation: K+ (Potassium) / Anion: CN- (Cyanide)
3. No Roman Numerals

Name: Potassium Cyanide

Example: Fe(C2H3O2)3

1. C2H3O2-
2. Cation: Fe3+ (Iron) / Anion: C2H3O2- (Acetate)
3. Needs Roman Numerals

Name: Iron (III) Acetate

Writing Formulas for Ternary Ionic Compounds: Steps

1. Write the symbols (cation + anion)
2. Balance the charges to equal zero(criss-cross)

Criss-Cross Example

- Sodium Phosphate

Ca2+ PO3 3- to Ca3(PO3)2

Example: Potassium Cyanide

1. Cation: K+ (Potassium) / Anion: CN- (Cyanide)
2. KCN

Example: Chromium (III) Nitrite

1. Cation: Cr3+ (Chromium) / Anion: NO2- (Nitrite)
2. Cr2NO3

Which elements have EXCEPTIONS?

- Zn (Zinc)
- Ag (Silver)
- Sn (Tin)
- Pb (Lead)

Zinc's exception

1. Does not need Roman Numerals
2. It always has a 2+ charge

Silver's exception

1. Does not need Roman Numerals
2. It always has a + charge

Tin's exception

1. Needs Roman Numerals
2. Can either have a 2+ or 4+ charge

Lead's exception

1. Needs Roman Numerals
2. Can either have a 2+ or 4+ charge

(Metallic Bonds)

Metals are not

ions

Metals share several properties with

ionic compounds

The bonding in both metals and ionic compounds is based on the attraction of particles with

opposite charges

An ionic bond is the attraction between the ________________ and the _________________

cation; anion

A metallic bond is the attraction between a _______________________ and the delocalized _______________.

metallic cation; delocalized electrons

Metals have

delocalized electrons

The delocalized electrons are able to

move freely from one atom to the next

Metal atoms in a metallic solid contribute their valence electrons to form

a sea of electrons

The sea of electrons surrounds

the metal cations

Properties of Metals

1. Melting Points vary greatly
2. Malleable (hammered into sheets)
3. Ductile (drawn into wires)
4. Conduct heat and electricity (even in the solid phase)

Metal Alloys

A mixture of elements that has metallic properties

Alloy: Steel

1. Composition and Ingredients:
- Iron 99%
- Carbon 1%

2. Use for
- Rails
- Ships
- Vehicles

Alloy: Brass

1. Composition and Ingredients:
- Copper 65%
- Zinc 35%

2. Use for
- Electric switch
- Door knobs

The force that holds two atoms together is called a

chemical bond

In electron transfer involving a metallic atom and a nonmetallic atom during ion formation

the nonmetallic atom gains electrons from the metallic atom.

How do the metallic ions differ from the ions that exist in ionic solids?

They don't completely lose electrons