CHEMICAL BONDING IONIC BONDS COVALENT BONDS HYDROGEN BONDS METALLIC BONDS.

CHEMICAL BONDING

• IONIC BONDS

• COVALENT BONDS

• HYDROGEN BONDS

• METALLIC BONDS

IONIC BONDING

When an atom of a nonmetaltakes one or more electrons

from an atom of a metalso both atoms end up with

eight valence electrons

IONIC BONDING

IS THE COMPOUND AN IONIC COMPOUND?

METALMETAL NONMETAL

SUBSCRIPTS

IONIC BOND FORMATION

Neutral atoms come near each other. Electron(s) are transferred from the Metal atom to the Non-metal atom. They stick together because of electrostatic forces, like magnets.

IONIC BONDING

Metals will tend to lose electrons and become

POSITIVE CATIONS

Normal sodium atom loses one electron to become sodium ion

IONIC BONDING

Nonmetals will tend to gain electrons and become

NEGATIVE ANIONS

Normal chlorine atom gains an electron to become a chloride ion

POLYATOMIC IONS--a group of atoms that act like one ion

NH4+1--ammonium ion

CO3-2--carbonate ion

PO4-3--phosphate ion

IONIC BONDING

IONIC BONDING

SODIUM SULFATE

Properties of Ionic Compounds

• Crystalline structure.

• A regular repeating arrangement of ions in the solid.

• Ions are strongly bonded.

• Structure is rigid.

• High melting points- because of strong forces between ions.

Crystalline structure

+

+

+ +

+

+

++

+

--

--

- --

--

The POSITIVE CATIONS stick to the

NEGATIVE ANIONS, like

a magnet.

Do they Conduct?

• Conducting electricity is allowing charges to move.

• In a solid, the ions are locked in place.• Ionic solids are insulators.• When melted, the ions can move

around.• Melted ionic compounds conduct.• First get them to 800ºC.• Dissolved in water they conduct.

Ionic solids are brittle

+ - + -+- +-

+ - + -+- +-

Ionic solids are brittle

+ - + -

+- +-+ - + -

+- +-

• Strong Repulsion breaks crystal apart.

COVALENT BONDING

When an atom of one nonmetal

shares one or more electrons

with an atom of another

nonmetal so both atoms

end up witheight valence electrons

COVALENT BOND FORMATION

When one nonmetal shares one or more electrons with an atom of another nonmetal so both atoms end up with eight valence electrons

COVALENT BONDING

IS THE COMPOUND A COVALENT COMPOUND?

NONMETALNONMETAL NONMETAL

YES since it is made of only nonmetal elementsYES since it is made of only nonmetal elements

Covalent bonding

• Fluorine has seven valence electrons

F

Covalent bonding

• Fluorine has seven valence electrons

• A second atom also has seven

F F

Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons

F F

Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons

F F

Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons

F F

Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons

F F

Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons

F F

Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons Both end with full orbitals

F F

Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons Both end with full orbitals

F F8 Valence electrons

Covalent bonding Fluorine has seven valence electrons A second atom also has seven By sharing electrons Both end with full orbitals

F F8 Valence electrons

Single Covalent Bond

• A sharing of two valence electrons.

• Only nonmetals and Hydrogen.

• Different from an ionic bond because they actually form molecules.

• Two specific atoms are joined.

• In an ionic solid you can’t tell which atom the electrons moved from or to.

Water

H

O

Each hydrogen has 1 valence electron

Each hydrogen wants 1 more

The oxygen has 6 valence electrons

The oxygen wants 2 more

They share to make each other happy

Water

• Put the pieces together• The first hydrogen is happy• The oxygen still wants one more

H O

Water

• The second hydrogen attaches

• Every atom has full energy levels

H OH

Carbon dioxide• CO2 - Carbon is central atom (

I have to tell you)

• Carbon has 4 valence electrons

• Wants 4 more

• Oxygen has 6 valence electrons

• Wants 2 moreO

C

Carbon dioxide

• Attaching 1 oxygen leaves the oxygen 1 short and the carbon 3 short

OC

Carbon dioxide Attaching the second oxygen leaves

both oxygen 1 short and the carbon 2 short

OCO

Carbon dioxide The only solution is to share more

OCO

Carbon dioxide The only solution is to share more

OCO

Carbon dioxide The only solution is to share more

OCO

Carbon dioxide The only solution is to share more

OCO

Carbon dioxide The only solution is to share more

OCO

Carbon dioxide The only solution is to share more

OCO

Carbon dioxide The only solution is to share more Requires two double bonds Each atom gets to count all the atoms in

the bond

OCO

Carbon dioxide The only solution is to share more Requires two double bonds Each atom gets to count all the atoms in

the bond

OCO8 valence electrons

Carbon dioxide The only solution is to share more Requires two double bonds Each atom gets to count all the atoms in

the bond

OCO8 valence electrons

Carbon dioxide The only solution is to share more Requires two double bonds Each atom gets to count all the atoms in

the bond

OCO

8 valence electrons

How to draw them

• Add up all the valence electrons.• Count up the total number of electrons to

make all atoms happy.• Subtract.• Divide by 2• Tells you how many bonds - draw them.• Fill in the rest of the valence electrons to fill

atoms up.

Examples

• HCN C is central atom• N - has 5 valence electrons wants 8• C - has 4 valence electrons wants 8• H - has 1 valence electrons wants 2

• HCN has 5+4+1 = 10

• HCN wants 8+8+2 = 18• (18-10)/2= 4 bonds• 3 atoms with 4 bonds -will require multiple bonds -

not to H

HCN

• Put in single bonds• Need 2 more bonds• Must go between C and N

NH C

HCN Put in single bonds Need 2 more bonds Must go between C and N Uses 8 electrons - 2 more to add

NH C

HCN Put in single bonds Need 2 more bonds Must go between C and N Uses 8 electrons - 2 more to add Must go on N to fill octet

NH C

Polar Bonds

• When the atoms in a bond are the same, the electrons are shared equally.

• This is a nonpolar covalent bond.• When two different atoms are connected,

the atoms may not be shared equally.• This is a polar covalent bond.• How do we measure how strong the atoms

pull on electrons?

Electronegativity

• A measure of how strongly the atoms attract electrons in a bond.

• The bigger the electronegativity difference the more polar the bond.

• 0.0 - 0.3 Covalent nonpolar

• 0.3 - 1.67 Covalent polar

• >1.67 Ionic

How to show a bond is polar• Isn’t a whole charge just a partial chargemeans a partially positivemeans a partially negative

• The Cl pulls harder on the electrons• The electrons spend more time near the Cl

H Cl

Polar Molecules

Molecules with ends

Polar Molecules

• Molecules with a positive and a negative end• Requires two things to be true The molecule must contain polar bonds

This can be determined from differences in electronegativity.

Symmetry can not cancel out the effects of the polar bonds.

Must determine geometry first.

Is it polar?

• HF

• H2O

• NH3

• CCl4

• CO2

Intermolecular Forces

What holds molecules to each other

Intermolecular Forces

• They are what make solid and liquid molecular compounds possible.

• The weakest are called van der Waal’s forces - there are two kinds

• Dispersion forces• Dipole Interactions

– depend on the number of electrons – more electrons stronger forces– Bigger molecules

Dipole interactions

• Depend on the number of electrons

• More electrons stronger forces

• Bigger molecules more electrons

• Fluorine is a gas

• Bromine is a liquid

• Iodine is a solid

Dipole interactions

• Occur when polar molecules are attracted to each other.

• Slightly stronger than dispersion forces.

• Opposites attract but not completely hooked like in ionic solids.

Dipole interactions

• Occur when polar molecules are attracted to each other.

• Slightly stronger than dispersion forces.

• Opposites attract but not completely hooked like in ionic solids.

H F

H F

Dipole Interactions

Hydrogen bonding

• Are the attractive force caused by hydrogen bonded to F, O, or N.

• F, O, and N are very electronegative so it is a very strong dipole.

• The hydrogen partially share with the lone pair in the molecule next to it.

• The strongest of the intermolecular forces.

Hydrogen Bonding

HH

O+ -

+

H HO+-

+

Hydrogen bonding

HH

O H HO

HH

O

H

H

OH

HO

H

HO HH

O

MOLECULAR SHAPES

OFCOVALENT

COMPOUNDS

VSepR tHEORY

What Vsepr means

Since electrons do not like each other, because of their negative charges, they orient themselves as far apart as possible, from each other.

This leads to molecules having specific shapes.

Things to remember

•Atoms bond to form an Octet (8 outer electrons/full outer energy level)

•Bonded electrons take up less space then un-bonded/unshared pairs of electrons.

Linear

•Number of Bonds = 2

•Number of Shared Pairs of Electrons = 2

•Bond Angle = 180°

EXAMPLE:

BeF2

Trigonal Planar

•Number of Bonds = 3

•Number of Shared Pairs of Electrons = 3

•Number of Unshared Pairs of Electrons = 0

•Bond Angle = 120°

EXAMPLE:

GaF3

Bent #1

•Number of Bonds = 2

•Number of Shared Pairs of Electrons = 2

•Number of Unshared Pairs of Electrons = 2

•Bond Angle = < 120°

EXAMPLE:

H2O

Bent #2

•Number of Bonds = 2

•Number of Shared Pairs of Electrons = 2

•Number of Unshared Pairs of Electrons = 1

•Bond Angle = >120°

EXAMPLE:

O3

Tetrahedral

•Number of Bonds = 4

•Number of Shared Pairs of Electrons = 4

•Number of Unshared Pairs of Electrons = 0

•Bond Angle = 109.5°

EXAMPLE:

CH4

Trigonal Pyramidal

•Number of Bonds = 3

•Number of Shared Pairs of Electrons = 4

•Number of Unshared Pairs of Electrons = 1

•Bond Angle = <109.5°

EXAMPLE:

NH3

Trigonal bIPyramidal

•Number of Bonds = 5

•Number of Shared Pairs of Electrons = 5

•Number of Unshared Pairs of Electrons = 0

•Bond Angle = <120°

EXAMPLE:

NbF5

OCTAHEDRAL

•Number of Bonds = 6

•Number of Shared Pairs of Electrons = 6

•Number of Unshared Pairs of Electrons = 1

•Bond Angle = 90°

EXAMPLE:

SF6

Metallic Bonds

• How atoms are held together in the solid.

• Metals hold onto there valence electrons very weakly.

• Think of them as positive ions floating in a sea of electrons.

Sea of Electrons

+ + + ++ + + +

+ + + +

• Electrons are free to move through the solid.

• Metals conduct electricity.

Metals are Malleable

• Hammered into shape (bend).

• Ductile - drawn into wires.

Malleable

+ + + ++ + + +

+ + + +

Malleable

+ + + +

+ + + ++ + + +

• Electrons allow atoms to slide by.