Chemical Bonds

● Molecules are made up of more than one atom.

● Compounds are made up of more than one element.

● When atoms combine to make molecules, they form chemical bonds.

● Types of Bonds:● Ionic Bonds● Covalent Bonds● Metallic Bonds

Types of Chemical Bonds

● Ionic Bond

● Covalent Bond

● Metallic Bond

Relative Strengths of Bonds

Ionic Bond Strongest

Covalent Bond

Metallic Bond Weakest

Chemical Bonding is represented using Lewis Dot Diagrams.

REMINDERS: (do not need to write)

● Valence electrons (dots) are placed around the four sides of the element symbol.

● Electrons (dots) begin to pair up only when no more single spaces are left.

● Single dots show where the atom can form a chemical bond.

***Lewis Dot Structures

http://www.youtube.com/watch?v=bK9nMHTLhmk

Ionic Bond: an attractive force between a metal and a nonmetal.

Structure of Ionic Bonds

● Crystalline in Structure – Form lattices● Relatively high melting and boiling points● Brittle – the lattice can be broken if enough external force

applied

● Conduct electricity only when melted or dissolved in water

● Many (not all) are soluble in water – those that dissolve in water form solutions that conduct electricity are electrolytes (particles that conduct electricity in solution)

Oxidation Numbers

Bond Formation:

opposite charges attract

•occurs when electrons are transferred •forms ions that attract each other

Ionic Bonding

● Transfer of electrons● From metal → non-metal● Results from the electrostatic charge between a

metal ion (cation - positive charge) and a non-metal ion (anion – negative charge)● This means that we are transfering from positive to negative

oxidation numbers

● The overall number of negative and positive charges must be the same – aka they must cancel out and equal zero

Time to Practice

You need a Bonding Basics handout

We will be using this for the entire unit.

You are completing “Basics” and “Section B” today

Test Analysis

● Pick up a test analyis sheet● Pick up your bubble sheet from the

back● Find two different colors

I will put the key on the board

No

Ions

!

+4-4

-1

What does a chemical formula tell you?

1) Number and type of atoms.

2) Type of ions.

3) Formula mass

Write this slide! The title and 1-3

1)Write the metal first, then the nonmetal. Al3+ O2-

2) Switch the charge values except if they can be reduced. Al2

3+ O32-

Notice: The sum of the charges equals zero.2(+3) + 3(-2) → (+6) + (-6) = 0

3) Write the formula without the charges. Al2O3

*****PRACTICE MAKES PERFECT!!!

Writing Binary Formulas: The Steps

**Write this slide!**

Do this for the 6 ionic bonds in your pink packet.

Name the metal, then the nonmetal; change ending to –ide.

KI potassium iodide

Ca3N2 calcium nitride

BaCl2 barium chloride

NaH sodium hydride

**Write this slide!**

Practice: Binary Ionic Compounds

1) CaBr2 = Calcium Bromide2) Na2S3) AgCl4) SrBr25) Al2O36) Li2S

**Write this slide!**

Practice: Binary Ionic Compounds

1) CaBr22) Na2S3) AgCl4) SrBr25) Al2O36) Li2S

Calcium Bromide

Sodium Sulfide

Silver Chloride

Strontium Bromide

Aluminum Oxide

Lithium Sulfide

Writing Binary Ionic Compounds

● Sodium chloride → NaCl● Calcium bromide →● Potassium nitride →● Aluminum sulfide →● Barium iodide →● Lithium Oxide →

**Write this slide!**

Writing Binary Ionic Compounds

● Sodium chloride →● Calcium bromide →● Potassium nitride →● Aluminum sulfide →● Barium iodide →● Lithium Oxide →

NaClCaBr2

K3N

Al2S3

BaI2Li2O

Polyatomic IonsThis chart is on the back of your orange table OR on the

white periodic table

Combining Polyatomic Ions

● More than one CAPITAL LETTER next to each other

● Will end in “-ate” or “-ite”● Exceptions: Hydroxide, Ammonium

2+1-1-

If more than one polyatomic ion, use ( ).

**Write this slide!**

Aluminum Sulfate

● For every 2 aluminum ions (Al3+), you need 3 sulfate ions (SO4

2-). ● The combined

charges add up to zero.

**Write the example below!**

Practice: Write the Compound

*remember, first element is USUALLY on P. Table, Second is polyatomic ion because it ends in -ate, -ite or is hydroxide

● Potassium nitrate ___________ ● Sodium phosphate _________

● Calcium hydroxide _________

● Ammonium sulfate _________● Both of these are on the polyatomic ion chart!

**Write this slide!**

Practice: Write the Compound

● Potassium nitrate = KNO3 ● Sodium phosphate = Na3PO4

● Calcium hydroxide = Ca(OH)2

● Ammonium sulfate = (NH4)2SO4

Metallic Bonding

Metallic Bonding