BRN: What do you see?

Bonding

New section in table of contents

What is an ionic compound?

KC 1: An ionic compound consists of a metal and a non-metal bound together in a lattice structure by ionic bonds

KC 2: An ionic compound = metal + nonmetal

Or cation + anion

Ionic Compounds

Ionic Compounds

KC 3: Cation – positively charged ion

KC 4: Anion – negatively charged ion

Polyatomic Ions “Poly” = many

“atomic” = atoms

Ion = charged

KC 5: Polyatomic ion = many atoms bonded together having an overall charge

See periodic table

Ionic Bonding

KC 6: Ionic Bond – bond formed through electrostatic attraction between 2 oppositely charged ions

Review: What is an ion? Different number of electrons from protons

Not a neutral atom

Contains a charge

Ionic bond is formed through electrostatic attraction between 2 oppositely charged ions

These ions are attracted to one another and form what is called a lattice or crystalline structure

Ionic Bonding

8 is the magic number!

KC 7: All atoms are trying to reach a valence shell of 8 – like a noble gas

KC 8: If this cannot be achieved easily, an atom will lose electrons to have a valence shell of zero

Ionic Bonding

Each atom forms a charge that is related to its number of valence electrons

Example: calcium – 1s22s22p63s23p64s2

2 valence electrons

8 is the magic number!

Is it easier to gain 6 or lose 2?

Ionic Bonding

Covalent Compounds & Bonding

KC 9: Covalent compounds consist of 2 or more nonmetals bonded together

KC 10: A covalent bond is formed from the sharing of electrons

Ionic Bond vs.Covalent Bond

Naming Puzzle

Metal Cation Charge Nonmetal Anion ChargeCompound (Formula)

Total charge

Name

Ca     F          

Naming Rules: If you need these for your reference, you can print them from my website

We need to spend the class time practicing, not copying down the rules

Naming Ionic Compounds – formula to name

Type A:Metal + Nonmetal

Name the metal

Name the nonmetal

Change the nonmetal ending

to “ide”

Type B: Metal +

Polyatomic Ion

Name the metal

Name the polyatomic ion

Type C: Transition Metal + Nonmetal

Name the transition metal

Find the charge of the metal and place in roman

numerals

Name the nonmetal

Naming Ionic Compounds – formula to name

Type A:Metal +

Nonmetal

Example: KCl

Type B: Metal +

Polyatomic Ion

Example: Ca(NO3)2

Type C: Transition Metal +

Nonmetal

Example: FeF2

Creating Ionic Compounds – the switcheroo!

When bonding a metal and nonmetal in an ionic compound, the charges have to balance

To do this, you just switch the charges and cross them down: the switcheroo

Can also be done the opposite way to determine charges

The Switcheroo!

Example: aluminum chloride

EXCEPTION ALERT!!

What if you do the switcheroo and the charge for a nonmetal does not come out correctly?

EXCEPTION ALERT!!

If the charge of the nonmetal comes out wrong, that means the charges have reduced

• To correct the charge, just multiply both charges by the necessary number to make it the charge that you know it is

Naming Ionic compounds

- Name to formula

Write the formula for the compound using

subscripts

Write the element symbol

Determine the charge of each

element from looking at the periodic table

Do the switcheroo!Cross charges down

Naming Rules – name to formula

Example: copper (II) chloride

Covalent Compounds

-formula to name

Write the Greek prefix for the first

element and name it

1 = mono 6 = hexa2 = di 7 = hepta3 = tri 8 = octa4 = tetra 9 = nano5 = penta 10 = deca

Write the prefix for the second element

and name it

Naming Rules – Covalent Compounds

Example – NO2

Example – dibromine hexaphosphide

The only way to get better

at naming and figuring out charges is to PRACTICE!!

Bonding

KC 11: Some molecules are more stable when they are found as diatomic – two of the same element covalently bonded

BrINClHOF

BromineIodineNitrogenChlorineHydrogenOxygenFluorine

Bonding

KC 12: Lewis Structure Rules

1. Draw skeleton of molecule or compound and count total valence electrons able to use

2. Give all elements full octet and a single bond between elements.

3. Count number of electrons in drawing from step #2 and compare to number of electrons allowed

4. If too many, do the “move a pair lose a pair” rule until you have the correct number of electrons Move electrons from outside in to form double or triple bond then erase a pair of

electrons from the outside

How many electrons does hydrogen have?

Will it be happy with 8?

NO!

KC 13: Hydrogen follows the duet rule – only needs 2 electrons to be happy

EXCEPTION ALERT!!

Lewis Structure Rules

1. Draw skeleton of molecule or compound and count total number of valence electrons to use Follows logic; place the element that is only contained

once in the middle

Example: CO2

C = 4e-

O = 6 x 2 = 12e-

Total = 16e-

Lewis Structure Rules

2. Give all elements full octet (8 around each element) and a single bond between elements.

Example: CO2 16e-

Lewis Structure Rules

3. Count number of electrons in drawing from step #2 and compare to number of electrons allowed

Example: CO2

Lewis Structure Rules

4. If too many, do the move a pair lose a pair rule until you have the correct number of electrons

Move electrons from outside in to form double or triple bond then erase a pair of electrons from the outside

Example: CO2

**Cannot break octet rule!!**

Lewis Structure Rules

Most Lewis structures for compounds follow the common bonding patterns:

4 bonds 3 bonds 2 bonds 1 bond

0 L.P. 1 L.P. 2 L.P. 3L.P.

Bonds:

Lone Pairs:

Shapes of Molecules

The Lewis structure can be transferred into a 3D model that tells us the exact shape, bond angles, and polarity of molecules

# of things # bonds # lone

pairsMolecular geometry

Bond angle Example

2 2 0 linear 180 CO2

3 3 0 Trigonal planar 120 BF3

3 2 1 Bent <120 SO2

4 4 0 tetrahedral <109.5 CH4

4 3 1 Trigonal pyramidal <109.5 NH3

4 2 2 Bent <109.5 H2O

Polarity

KC 14: The shape of the molecule and the electronegativity of the elements determines the molecule’s polarity

We use vectors to represent polarity

Demonstration:

H2O

Your turn!

You are going to be given a molecule to build and show to the class

You must include: Name

Formula

Lewis structure

Molecular geometry

polarity

Review Activity