How many valence electrons do atoms want to

obtain?

A bond is the electrostatic force of attraction between two particles (atoms, ions or molecules)

•They are formed/broken during Chemical Reactions

•Formed = release energy

•Broken = absorb energy

Valence Electrons - want to achieve happiness

“Octet Rule” - want a full valence shell = HAPPY!

Ionic

Covalent

Metallic

- metal and

nonmetal

- nonmetal +

nonmetal

- metal + metal

Atoms Involved

                                    

Find the correct formula for a compound!!•Use the oxidation #’s•Put the positive one first

H+1 + O-

2 H2O

Ca + Br CaBr2+2 -1

Mg + (OH) Mg(OH)2+2 -1

Sr + O Sr2O2+2 -2 SrO

Na + Se Na2Se+1 -2

Fe (III) + (HCO3) Fe(HCO3)3+3 -1

Al + PO4 Al3(PO4)3+3 -3 Al(PO4)

Remember: A bond between a metal and a non-metal atom The metal keeps its name, and the non-metal ends in -ide

KBr

CaCl2

Potassium BromideCalcium Chloride

What are the formulas for the compounds between:

Oxygen and Phosphorus

Iodine and Barium

Speed

Bonding

HON – 17

As pure elements, these seven elements form molecules containing two atoms

   

 

H2

N2 O2 F2

Cl2Br2

I2

HON – 17

As pure elements, these seven elements form molecules containing two atoms

   

 

Transition Elements

Atoms combine to form compoundsBy bonding atoms together, their properties change

I. Bonding

A.Chemical Bond

This is the attractive force between atoms or ions

Results from the rearrangement of valence electrons

B. Energy Changes

As a chemical bond forms, atoms are brought to a lower energy state

Free atoms have more energy than bonded atoms

H2O2H2O

EXOTHERMIC

As we said before, atoms can bond together by moving their valence electrons around

Actually, atoms can either lose, gain or share electrons. This gives us several types of bonds

Ionic Bond

BONDS BETWEEN ATOMSAtoms transfer electrons

Creates ions

Forming ions An ion is formed when atoms lose or gain electrons

Ion = Charged atom due to a loss or gain of electrons

e-e-e-e-e--+

Binary Ionic Compounds

- change the end of the non-metal to -ide

MgI2 Magnesium Iodide

CoBr2 K2O

CoBr3

Potassium Oxide

Cobalt (II) Bromide

Cobalt (III) Bromide

When you have more than two elements, refer to Ref. Table E.

NaOH Sodium HydroxideAmmonium NitritePotassium

PermanganateKMnO4

(NH4)(NO2)

Ni2(CrO4)3 Nickel (II) chromate

What would the oxidation number be for Iron in the

following compounds:

Fe2O3

FeS

You must look at the types of atoms and their electronegativity differences.

Ionic - bond between a metal and a non-metal Electronegativity difference should be = to or > than 2.0 This means that one atom can pull an e- from another

atom

Results in the formation of ions

Mn + F

1.6 - 4.0 = 2.4

K + O 0.8 - 3.4 = 2.6

Big Dog vs Little Dog

Metal + nonmetal Ionic bond

• Further apart on the Periodic table

Higher ionic character• Greater difference in

electronegativity

High ionic character

Higher ionic character

=

Writing Formulas Lab

What are the formulas for the following compounds:

Sodium thiocyanate

Ammonium oxide

Compound Naming Race

Writing Formulas Lab

What type of bonds are in the following compounds?

Calcium Bromide

Sulfur Oxide

You must look at the types of atoms and their electronegativity differences.

Covalent -

bond between two non-metals Electronegativity difference should be less than 2.0

This means that one atom is not able to pull an e- away

DOES NOT FORM IONS!!!

Two of the same sized dogs

C

+

Cl 2.6 - 3.2 = 0.6

I +

I 2.7 - 2.7 = 0.0

Covalent -

bond between two non-metals Specific Types

Polar Covalent Electronegativity differences of 0.5 – 1.9

- the unequal sharing of e-

Fe2O3 1.8 - 3.4 = 1.6

Results in partial charges on the atom

Non-Polar Covalent

- the equal sharing of e-

Electronegativity differences of 0.0 – 0.4

Usually only in diatomic molecules O2 3.4 - 3.4 = 0.0

Nonmetal + nonmetal• Covalent bond• Small difference

in electronegativity

Ternary substance- compound containing polyatomic ion

Polyatomic ion is covalently bonded together

Bond between polyatomic ion and atom is ionic

MgSO4

covalent

Ionic

Results in a compound having both IONIC and COVALENT bonds

Metal + Metal Metallic bond

Alloy -Different metal atoms mixed together

Brass –

= sea of electronsElectrons are free to move all over, not bound to one nucleus

Bronze – copper and tin

copper and zinc

Gold – Gold, silver, copper

Ionic compounds can also be drawn as Lewis structures.

Positive ion Cation

Since all the valence electrons are removed, no valence electrons are shown.

Na

Negative ion Anion

The charge is written above+

The added valence electrons indicate a full valence shell.

Cl

Brackets are added and the charge is written on the outside

-

LEWIS STRUCTURES OF IONS AND IONIC COMPOUNDS

Ionic compounds

Write the positive ion next to the negative ion, and include their charges

Na+

Cl-

Covalent compounds

First write element symbols and then draw their valance electrons.

H2

OH H O

Now move the atoms to pair up any unpaired electrons

HHO

CO2

Give the formula and dot diagram for the compound formed from the following compound:

EN difference ?

Fluorine and Magnesium

Give the formula and dot diagram for the compound formed from the following

elements:

EN difference ?

Strontium and Bromine

Give the formula and dot diagram for the compound formed from the following

elements:

EN difference ?

NH3

Give the formula and dot diagram for the compound formed from the following

elements:

EN difference ?

Sodium hydroxideGive the dot diagram for the compound:

Give the formula and dot diagram for the compound formed from the following

elements.

Phosphorus and Chlorine

Pδ-

δ-

δ-

δ+

Cl

Cl

Cl

Cl

Cl

Cl

What are they? • The attractive force between the hydrogen attached to a highly electronegative atom of one molecule and a highly electronegative atom (N, O, F only) of a different molecule.

• Only found in polar covalent compounds

• Individually a very weak bond

•Very High M.P. and B.P.

•Less dense as a solid

•High Heat of Vaporization• Sweating, climate moderation

•High Surface Tension

Unique properties of water

Fewer molecules to be attracted to therefore a stronger attraction

Hydrogen bonding is the strongest of the intermolecular bonds!!!!

(click for video)

Bubble Lab

Strontium and Iodine

Give the formula and dot diagram for the compound formed from the following

elements:

Sr II

-1

-1

+2

BUBBLES

The Jesus lizard – the Basilisk lizard

scroll down to view movie

Rules are similar to ionic compounds, just need to add prefixes for the number of

atoms1

2

3

4

5

6

7

8

9

10

mono-di-

tri-

tetra-

penta-

hexa-

hepta-octa-

nona-

deca-

Try the following:

CO2

CCl4

Dinitrogen monoxide

Diphosphorus pentoxide

Carbon dioxide

Carbon tetrachloride

N2O

P2O5

Naming Covalent

Molecules wkst 1

A. State evidence that indicates that NH3 has stronger intermolecular forces of attraction than CF4.

B. Draw the lewis dot diagram for CF4. Is it a polar or non-polar molecule

Physical Properties of CF4 and NH3 at STP

Compound MP (ºC) BP (ºC) Solubility in water @ 20ºC

CF4 -183.6 -127.8 Insoluble

NH3 -77.7 -33.3 Soluble

Molecules -are only covalently bonded

Polarity of molecules - - completely dependent on the shape of the molecule

A molecule is either polar or non-polar with respect to charge

- molecules are only polar if they have polar covalent bonds

- if you can draw one straight line and all the (+) are on one side and all the (-) are on the other side, the molecule is polar

DipoleMolecule which has a + side and a - side

Assigning + and - to atoms

The atom with the higher electronegativity gets the -The atom with the lower electronegativity gets the +

Examples

O == C== O H--Cl

N

H H H- + -

nonpolar

+ -

polar

-

+ + +polar

Symmetrical charge distributionEqual distribution of charge

- results in the formation of a Nonpolar molecule

Asymmetrical charge distributionNegative(-) end and Positive(+) end

- results in the formation of a Polar molecule

Molecular Polarity wkst

Explain, in terms of electrons, why the bonding in NaCl is

ionic?

Dissolve in polar solvents

Dissolve in non-polar solvents

Dissolve in polar solvents

A substance containing free ions that makes the substance electrically conductive

The process where ionic compounds split (separate) into their respective ions

Draw the Dot Diagrams for the following compounds and

determine if they are polar or non-polar, and name them:

H2O

CH4

Connectors # Needed Spheres # Needed

Sticks 6

Black 2

Red2

Springs 4 Yellow 4

You might have to share with another group to get 4.

Green 1

Blue 1

III. VSEPRClass Shape Model Example

AX Linear HCl

AX2 Linear CO2

AX3Trigonal Planar

BH3

AX4 Tetrahedral CH4

: AX3 Pyramidal NH3

..

:AX2BENT H2O

What are the names of the following compounds:

CoI3

MgSO4

A substance will conduct electricity IF it has freely moving charged particles Particles can be ions, electrons, etc. as long as they can move

Metal Conducts electricity in solid or liquid form

Freely moving electrons allows the electricity to flow.

Ionic substanceDoes NOT conduct in solid formIons are locked in placeHas charges, but not free movingLiquid When melted, can conduct electricityIons are mobile enough to move past each other

-+

--

---

+

+

++

+

SolutionIn solution, ions separate

Ions are free to move, conducts electricity

Dissociate

Covalent

Solid Doesn’t conduct electricity No charged particles

LiquidDoesn’t conduct electricity No charged particles

Solution Some types of covalent molecules can be broken down to make ions Ionization

Conducts some electricity, because only a few of the molecules in the sample are broken down

Used to determine a substances properties – only found in covalently bonded substances

Relatively weak compared to ionic, metallic, and even covalent bondsExamples

Dispersion forces – for your college educationDipole-Dipole forces – again something for collegeHydrogen bonding – we’ve done theseMolecule-ion attractions – we’ll look at these

FORCES BETWEEN MOLECULES(IMF)’S

Molecule-Ion Attractions – the attraction between the ions and molecules of water in a solution

A Good Animation

Ionic•Hard

•Good Conductors• Not as solids

•High MP & BP

•Dissolve in Polar Substances - water

Covalent•Generally soft

•Poor Conductors• No charged particles

•Low MP & BP

AKA – Molecular Substances

Coordinate Covalent Bond

Hydronium ion

Ammonium ion

- one atom donates BOTH electrons that are shared

OH

H

+ H+

HOH H

+

NHH

+ H+

H NH

H

HH +

Molecular Polarity handout

Lab Check in

Bonding Packet

LINEAR

TRIGONAL PLANAR TETRAHEDRAL

SEE ALSO POLARITY NOTE SHEET

Affect on Boiling Points

Stronger force = Higher Boiling Point

Give the name of a substance that can NOT conduct

electricity in the solid phase but can as a liquid. Explain

why.

Name the following compounds:

PCl3

K2C2O4

Covalent bonds are classified as single,

double,

or triple bonds depending on the number of electrons shared between the two nuclei.

Intermolecular Forces

11.2

Intermolecular forces are attractive forces between molecules.

Intramolecular forces hold atoms together in a molecule.

Intermolecular vs Intramolecular

• 41 kJ to vaporize 1 mole of water (inter)

• 930 kJ to break all O-H bonds in 1 mole of water (intra)

Generally, intermolecular forces are much weaker than intramolecular forces.

“Measure” of intermolecular force

boiling point

melting point

DHvap

DHfus

DHsub

What are the names of the following compounds:

KCH3COO

BaCr2O7

11.2

Types of Intermolecular Forces

3. Dipole-Dipole Forces

Attractive forces between polar molecules

Orientation of Polar Molecules in a Solid

11.2

FLORIDA STATE

Draw the electron dot diagram for the following :

Magnesium

Iodide ion

1. Barium Sulfite

2. SrS

3. Cesium Selenide

4. KClO3

5. Calcium Sulfide

6. BaCrO4

7. Strontium Fluoride8. NaNO3

9. Cs(ClO2)

10. Magnesium Oxalate

What types of chemical bonds

exist?

1. Barium Sulfate

2. CaO

3. Potassium Oxide

4. Na2CO3

5. Magnesium Oxide

6. SrCrO4

7. Barium Chloride

8. NaNO3

9. MgSO4

10. Beryllium Sulfite

Sodium Atom Chlorine Atom

+11 -11

Total charge

Atom is considered

Total charge

Atom is considered

+17 -17

0

neutral

0

neutral

IN AN IONIC BOND, ONE ELECTRON FROM SODIUM IS TRANSFERRED TO CHLORINE

-10

+1

a positive ion

-18

Called a Cation

-1 a negative ion

Called an Anion

CationAnion

Positive ion due to the loss of electronsNegative ion due to the gain of electrons

meow.

Examples - Determine the type of ion shown and explain how it was made from a neutral atom.

Ion Type of Ion How it was made

K+

Ca+2

O-2

Br-

cation Lost 1 electron

cation

anion

anion

Lost 2 electrons

Gained 2 electrons

Gained 1 electron

Draw the electron dot formula for neutral atoms of Na and F

Na F

All atoms want a full octet in their valence shell. This is a stable configuration. When ionic bonding occurs,the one valence electron in Na is transferred to F

+ -

Notice how both atoms have a full octet?F has gained an electron to get a total of 8.

Na uses its full shell underneath as a full valence

Na2

8 1

+

The attraction between the + and - ion causes the bond

Review Ionic bonds

1. Electrons are transferred2. Ions are created Cation lost e-, anion gained e-3. Very strong bond. Has high melting and boiling points, and a very rigid structure4. Creates ionic substances

Covalent Bondsa. Electrons in bonds

- No transfer of electrons- Electrons are shared between valence shell of atoms

- Weaker bonds than ionic

In covalent bonding, atoms get a full octet by sharing

electrons between their valence shells

Hydrogen and helium do not need 8 electrons, only 2

H HSo the molecule H2 looks likeH H

In covalent bonding, atoms still want to achieve a noble gas configuration

But rather than losing or gaining electrons, atoms now share an electron pair.

The shared electron pair

is called a bonding pair

COVALENT BONDS

The octet rule

Look at the parts of H2O

H H O O

H

H

This indicates that H2O looks likeH---O | H

Not H--O--H

Or H--H--O

Review

In a covalent bond, electrons are shared between valence shellsThere is NO transfer of electrons, so no ions are formedTheir bonds are weaker, have lower melting and boiling points

If atoms are covalently bonded, they make