Types of BondingTypes of BondingBy: Amanda McArthur and Elysia Dort

Covalent Bonding When two atoms share one or more of their

electrons to form one or more bonding pairs. Conductivity is normally poor. Covalent bonds sometimes form 3- dimensional

covalent networks. Three Dimensional covalent network are made up

of crystal like elements. These can include diamonds, quartz and boron.

Covalent bonds have low melting and boiling points.

Covalent bonds are also split into two other groups. Covalent Polar and Covalent Non-Polar.

Example

This is a perfect example of a Covalent Bond. Hydrogen has one electron and missing one electron from its valence shell. H when bonded with another H share their electron so they can both have a full valence shell. This results in a single bond.

Covalent Polar

Electro negativity difference is 0.5-1.6 Can occur between 2 non-metals, certain

metals and sometimes with both. Shares bonded electrons unequally between

atoms. The element in the bond that is negative is

the one with a higher electro negativity. This one has a stronger “pull” but not strong enough to take the electron for itself. This causes it to have the unequal sharing.

Covalent Polar

Charge is labeled with a sigma with either a positive or negative beside it. It also has an arrow pointed to the atom with the stronger electro negativity.

This example shows the Fluorine has a stronger electro negativity than Hydrogen.

Example- Try This

For each example:a) Draw itb) State the electro negative charge for each

and show the difference.1) HCl2) NaP

Answers

1a)

1b)Cl=3.0, H=2.1 3.0-2.1= 0.9 is the difference.

2a)

2b) Na=0.9, P=2.1 2.1-0.9= 1.2 is the difference.

Covalent Non-Polar

Has an electro negativity difference of 0-0.4

The two or more atoms must both be non-metals.

The electrons are shared equally. Charge is never shown. Their electro negativity must be the same

or close to it so this has a lot of bonding between the same elements.

Example- Try This

1) Draw the following and show the bonds.a)0b)Clc)AsS

Answer

a)

b)

c)

Electron Share Diagram

Starts off looking like the Lewis Dot Diagram by showing how many electrons are in the valence shell.

Then you show what electrons for each atom are being used to bond.

Once that is done you remove the lone pairs or lone electrons. Then for the bonded electrons represent them using a line.

Example- CO

Step one:

Step two:

Step three:

Try ThisDraw the share diagram for a)H 0b) HClc)AlBr

Answers A)

B)

C)

Properties of Ionic CompoundsProperties of Ionic Compounds

Crystalline solidsHigh melting and boiling pointsNormally soluble in waterGood conductors in molten stateVery hard and brittle

Ionic BondingIonic Bonding

Metal + Nonmetal ionic bond

Examples – Classification Metals Examples – Classification Metals and Non-metalsand Non-metals

NaCl Chlorine is a non- metal

Sodium is a metal So NaCl is an ionic compound

CO Oxygen is a non- metal

Carbon is a non-metalSo CO is NOT an ionic bond

Classification of bonds by electro- Classification of bonds by electro- negativitynegativity

You can classify bonds using an electro- negativity chart. (1.7+ is ionic!)

Describes the relative tendencies of the elements to attract electrons during bonding.

You do this by subtracting the electro- negativity of the elements in your compound.

NOTE- these numbers are just approximations and there are exceptions!

Covalent non- polar

Covalent polar

Ionic

0 - 0.4 0.5 – 1.6 1.7 +

Electro-negativity ChartElectro-negativity Chart

Examples Examples NaCl--- Na = 0.9 , Cl = 3.0

so… 3.0 – 0.9 = 2.1 Ionic is 1.7+ So Sodium chloride is Ionic

CO ---- C = 2.5 , O = 3.5so… 3.5 – 2.5 = 1.0 Ionic is 1.7+So Carbon dioxide is NOT ionic.

**HINT- notice that we never multiply the charge of oxygen even though there are 2 oxygen molecules!

Check your understandingCheck your understanding

Are these compounds ionic?(a)Classify using metal and non-metal

method(b) Classify using Electro-negativity

1.MgO2. BeCl

AnswersAnswersMgO--- Mg is a metal, O is a non-metal

Mg = 1.2, O = 3.5 3.5 – 1.2 = 2.3 Magnesium oxide is IONIC

BeCl -- Be is a metal, Cl is a non-metal Be = 1.5, Cl = 3.0 3.0 – 1.5 = 1.5 Beryllium chloride is IONIC

Electron Dot DiagramsElectron Dot DiagramsAlso known as Lewis structuresHelp show the valence electrons present

on an element or compound.Valence electrons- the electrons that are

located on the outermost shell of an element.

They give us a visual image of how ionic bonds works.

Examples- ElementsExamples- Elements

Lithium

Li – 1 dot, 1 valence electron

Phosphorus

P - 5 dots, 5 valence electrons

Electron Dot Diagram ChartElectron Dot Diagram Chart# of valence electrons

1 2 3 4 6 7

Example hydrogen

calcium boron nitrogen sulfur Fluorine

Group 1 2 13 14 16 17

Electron Dot

Diagram H

Ca B

N S F

Check your understandingCheck your understanding

Draw the dot diagrams for the following elements:

Lithium

Aluminum

AnswersAnswersLi--- lithium is in the first group so it has

one valence electron.

Li

Al--- aluminum is in the 13th group so it has 3 valence electrons.

Al

Cations and AnionsCations and AnionsDuring ionic bonding elements either gain

or lose electrons.Cations- elements that lost electrons

during bonding making them positive (+).Anions- elements that gained electrons

during bonding making them negative.(-)Examples: & - cations

& -anions

Electron Dot Diagrams- Electron Dot Diagrams- CompoundsCompounds

Compounds gain or lose electrons to try and form a stable octet.

Octet- a full shell of valence electrons. (Normally 8 except 2 for 1st shell)

Elements do this by trying to form the nearest noble gas.

Ex. Potassium would try to form Argon by losing one electron making the potassium ion.

ExamplesExamplesKI-

K + I the electron moves from K to I giving both potassium and iodine 8 valence electrons.

(K) + ( I ) KI

ExamplesExamplesLi S

Li + Li + S The two lithiums give an electron each giving sulfur a total of 8 electrons and both lithiums eight valance electrons.

(Li) + (Li) + ( S ) Li S

Hydrogen BondingHydrogen BondingHydrogen bonds to very electronegative

atoms (F- 4.0, O- 3.5, N- 3) Example of dipole-dipole forceStronger than normal dipole-dipole forces

weaker than covalent or ionic bonds.Hydrogen is mainly a proton (+)Hydrogen has a strong attraction to negative

parts of other moleculesWhen hydrogen bonds F,O or N it will attract

hydrogen’s electron leaving a unshielded hydrogen.

Hydrogen BondingHydrogen BondingBonded hydrogen naked proton

unshielded + charge greater force to break the bond Higher boiling point

Intermolecular Forces Deals with bonding with neighboring

elements. Has a weak force when compared to

intramolecular forces. Normally the atoms are very close to each

other. There are four kinds of Intermolecular forces.

They include London Forces, Dipole-dipole forces, Dipole-induced dipole forces and Ion-dipole forces.

Examples

Intramolecular Forces Deals with the force of attraction that hold

together atoms to make a molecule or compound.

There are three types of Intramolecular forces. They are Ionic, Covalent and Metallic bonding.

Can occur with metals and non-metals. The electrons are shared except in ionic

bonding which it is held together with electrostatic forces.

Example

Metallic BondingMetallic Bonding metal bonding with the same metal.Electrons move freely (roving sea of

electrons)Forms a lattice structure+ metal and – electron holds the atoms

together

Properties of Metallic BondsProperties of Metallic BondsConduct heat and electricityNormally have high melting

points and boiling pointsStrongMalleableReflect lightDuctile (can be drawn into a wire)

Dipole – dipole forcesDipole – dipole forcesWeak forces that attach the positive end of

one polar molecule with the negative end of another polar molecule.

Stronger than dispersion forces but weaker than hydrogen bonds, ionic or covalent bonds.

Polar and non-polar ends form when one elements do not share electrons equally.

Ex. Here Cl has more of the shared electrons.

Check Your UnderstandingCheck Your UnderstandingWhat types of bonds or forces are present

in the following situations?1.K gives an electron to Cl while bonding

making potassium chloride. 2.Cu bonds to itself making a copper ring.3.Hydrogen an chlorine but chlorine doesn’t

share the electrons equally.4.Frozen water attaches with other frozen

water molecules making ice.

AnswersAnswers

1. Ionic bond2. Metallic bond3. Dipole-dipole forces4. Hydrogen bond/ dipole- dipole forces

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