Chemical Bonding• In the next unit, we will discuss how

atoms join together to form a chemical

bond.

• There are 3 main types of chemical

bonds;

– Ionic Bonds

–Metallic Bonds

– Covalent Bonds

Ionic Bonding

• Electron Dot Diagrams (Lewis Diagrams)

– An electron dot diagram shows the number of valence

electrons around an atom.

– The group number tells us how many valence electrons the

atom has.

Ionic Bonding

• Electron dot diagrams

–Draw the electron dot diagrams of

Calcium, Aluminum, and oxygen.

Ionic Bonding• Ionic Compounds are substances

that form when a cation and an anion attract and ‘stick’ to each other.

• The force that’ glues’ the ions together is an electrostatic interaction. In other words, opposite charges attract.

Ionic Bonding• How do we know the sign and

magnitude of the charge an ion will form?

Group Charge 1 +1 2 +2 3 +3 4 +4/-4 5 -3 6 -2 7 -1 8 0

Ionic Bonding

• When a cation and an anion are

attracted to each other, an ionic

bond has formed.

Ionic Bonding

• What happens when a calcium ion

and a chloride ion come together?

What do you think the ratio of

cations to anions would be?

Ionic Bonding• Rules for forming and writing ionic

compounds;

– The sum of the positive and negative charges

has to equal zero. Ionic compounds are neutral.

– The cation is written first in the formula.

– A subscript is used to tell us how many of each

atom is in the ionic compound.

Na2O

Ionic Bonding

• Write the chemical formula for the

ionic compound that will form from

the following elements;

–Magnesium and sulfur

– Potassium and nitrogen

– Barium and bromine

– Aluminum and oxygen

Ionic Bonding• Some ions are polyatomic, they

consist of more than one atom.

-1 -2 -3

NO2-1 = nitrite SO3

-2 = sulfite PO4-3 =

phosphate

NO3-1 = nitrate SO4

-2 = sulfate

C2H3O2-1 =

acetate

Ionic Bonding• Writing chemical formulas of ionic

compounds that contain a

polyatomic ions;

– Same ‘rules’ as before but if there is

more than one polyatomic ion in the

compound, we need to use ( ).

– NaNO3 Ba(NO3)2 Mg(C2H3O2)2

Ionic Bonding

• Write the formula of the ionic compound

when the following ions bond;

– Barium ion and the carbonate ion

– Sodium ion and the hypochlorate ion

– Magnesium ion and the sulfate ion

– Aluminum and the hydroxide ion

– Lithium and the nitrate ion

Naming Ionic Compounds

• All you have to do is to say the name

of the cation, then the root of the

anion with the suffix ‘ide’.

Na2S = sodium sulfide

Naming Ionic Compounds

• If the anion or cation is polyatomic,

use the name of it without modifying

it.

Na2SO4 = sodium sulfate

Naming Ionic Compounds

• If the cation is a trasition metal, write

a roman numeral to indicate its

charge.

CoSO4 = cobalt (II) sulfate

Naming Ionic Compounds

• Name these ionic compounds;

– CaF2 = calcium fluoride

–Mg3N2 =

– AlPO4 =

– Ba(NO3)2 =

Naming Ionic Compounds

• Name these ionic compounds;

– CuF2 = copper (II) fluoride

–Mg3N2 =

– Pb3(PO4)2 =

– Ba(NO3)2 =

Ionic Compounds

• Some physical properties;

– Very high melting point.

– Very high boiling point.

– Brittle

– They have a crystalline structure

Ionic Compounds• Crystalline structure of ionic

compounds;

– A crystal is an orderly arrangement of

atoms.

Ionic Compounds• Crystalline structure of ionic

compounds;

– These crystalline structures ‘lock’ the

atoms of the compound in place.

– As a result, they form a structurally

strong solid.

Ionic Compounds

• Crystalline structure of ionic compounds;

– The 3-dimensional arrangement of atoms is referred to as a lattice,

not lettuce.

– The lattice energy is the amount of energy required to disrupt the

3-dimensional arrangement of atoms and change the solid ions into

gaseous ions.

– The lattice energy of NaCl is 13,500 Joules for every gram of NaCl.

Ionic Compounds• Crystalline structure of ionic

compounds;

– There are many types of crystalline

shapes of ionic compounds.

Ionic Compounds• Crystalline structure of ionic

compounds;

– There are many types of crystalline

shapes of ionic compounds.

Metallic Bonding

• What happens when two metallic

atoms interact?

• Do they ionize?

• Do they give away their electrons?

Metallic Bonding • When metallic atoms bond, the

metallic nuclei donate their electrons

to all of the atoms in the sample.

Metallic Bonding • This type of bonding between

metallic nuclei is called the ‘sea of

electrons’ model.

• It appears as if the metal atoms are

floating in an ocean of valence

electrons.

Metallic Bonding • This type of bonding gives metals

some unique properties.

• Metals are malleable – They can be

bent and they will stay in the shape.

Metallic Bonding • This type of bonding gives metals

some unique properties.

• Metals are ductile – They can be

pulled into long and thin wires.

Metallic Bonding

• An alloy is a mixture of metals.

• Some common alloys are;

– Brass (Cu and Zn)

Metallic Bonding

• An alloy is a mixture of metals.

• Some common alloys are;

– Bronze (Cu and Pb)

Metallic Bonding

• An alloy is a mixture of metals.

• Some common alloys are;

– 14 carat gold (Au and Ni)

Metallic Bonding

• An alloy is a mixture of metals.

• Some common alloys are;

– 14 carat gold (Au and Ni)

Metallic Bonding

• An alloy is a mixture of metals.

• Pure Gold (not an alloy);

– 24 carat gold (100 % Au)