Unit 5

Chemical CompoundsChapter 6

Objective 1

Describe the three types of chemical bonds.

There are three types of bonds:

Ionic Covalent Metallic

Bonding

How can you tell what type of bond is going to form?

You use what is called an electronegativity table.

Electronegativity- is the tendency for an atom to attract a shared pair of electrons.

Objective 2

Use electronegatitivity differences to determine the chemical bond that will form.

Elements EN Difference I or C?LI-ClC-HH-HN-HC-HK-BrNa-S

Elements EN Difference I or C?P-HI-IMg-ClC-OO-OS-ClN-NNa-Cl

Electronegativity Difference

Covalent Ionic 0 < 1.67

Objective 3

Recognize stable electron configurations.

Ionic Bonding

All elements combine to obtain a stable electron configuration.

Metals will lose electrons. Nonmetals will gain electrons.

Li-Cl

Lithium is 1s22s1. If lithium could lose one electron it would

be like the noble gas helium. Chlorine is 1s22s22p63s23p5. When lithium loses it’s one electron it

gives it to chlorine.

Li-Cl

So lithium will form a positive ion or cation with a charge of +1.

When chlorine receives the one electron it will form a negative ion or anion with a charge of –1.

The attraction of the oppositely charged ions will then form the compound LiCl, lithium chloride.

Li-Cl

We can represent this with what is called a dot diagram.

Combining Atoms Compound formed  

Lithium + Chlorine Lithium chloride

You teacher will draw this on the board. Copy!!

K-Br

Potassium + Bromine Potassium bromide

Mg-Cl

Magnesium + Chlorine Magnesium chloride

Na-Cl

Sodium + Chlorine Sodium chloride

Objective 4

Describe how an ionic bond forms and how ionization energy affects the process.

Conclusions:

Ionic bonding involves the transfer of one or more electrons from the metal to a nonmetal.

Energy changes are involved. a. Ionization energy-the amount of energy needed to

remove an electron from an atom.b. Electron affinity-the energy change when an

electron is added. The element that loses electrons will form a

positive ion. +1, +2, +3 for example.

Conclusions, cont. The alkali metals, alkaline earth metals and

aluminum will form positive ions equal to the group number.

The element that receives the transferred electron(s) will form a negative ion. -1, -2 or

-3 for example. The attraction of these oppositely charged ions

is what forms the ionic bond and a compound has been formed.

Properties of Ionic Compounds

1. High melting point.2. Nonconductor in the solid state. 3. Conductor when melted or dissolved in

solution. Ionic compounds are electrolytes-conductors of electricity in aqueous solution.

4. Brittle, or shatter when hit with a hammer.

Objective 5

Recognize and describe binary ionic compounds, metals with multiple ions, and polyatomic ions.

Ionic Compounds

Binary compounds -a compound made from only two elements.

Look at your List of Common Ions. An ionic compound can be made from any

positive ion from the front combined withany negative ion on the back.

Ionic Compounds

Li+ I-

The charges in a compound must be neutral. With +1 and –1 we will need one of each.

The formula is LiI.

Ionic Compounds

Li+ ClO3-ClO2

-

LiClO3 LiClO2

Ionic CompoundsLi+ C2O4

-2 Formula

need 2need 1 Li2C2O4

+2 -2 SO3

-2

need 2need 1 Li2SO3

PO4-3

need 3need 1+3 -3 Li3PO4

Ionic Compounds

Cr+2 I-

need 2 CrI2

ClO3-

Need 1 need 2+2 -2 Cr(ClO3)2

Must use parenthesis on polyatomic ion.

Ionic Compounds

Cr+2 C2O4-2

need 1 need 1 CrC2O4

SO3-2

need 1 need 1 CrSO3

PO4-3

need 3 need 2 Cr3(PO4)2

+6 -6Be sure to use parenthesis.

Ionic Bonding

Continue to complete the rest of the chart and check your work on the slides that follow.

KI KClO3 KClO2 K2C2O4 K2SO3

K3PO4 no parenthesis when there is just one.

AlI3 Al(ClO3)3 Al(ClO2)3 Al2(C2O4)3

Al2(SO3)3 AlPO4

ZnI2 Zn(ClO3)2 Zn(ClO2)2 ZnC2O4

ZnSO3 Zn3(PO4)2

Lab Ionic Compounds.

Use the foam ion cutouts to help you to write the formula for the ionic compounds.

Objective 6

Predict the composition of an ionic compound from its name.

 Let’s name the compounds we made in

Table 2.

Rules for Naming

1. Name the positive ion first.2. If the positive ion has more than one

charge, use a Roman numeral in the name. For example there is Cr+2 and Cr+3. So you have chromium (II) and chromium (III).

3. Name the negative ion second.

Table 2

1. Lithium iodide2. Lithium chlorate3. Lithium chlorite4. Lithium oxalate5. Lithium sulfite6. Lithium phosphate

Table 2

Use Roman numeral with metals that have more than one charge.

Chromium (II) iodide Chromium (II) chlorate Chromium (II) chlorite Chromium (II) oxalate Chromium (II) sulfite Chromium (II) phosphate

Table 2

Aluminum iodide Aluminum chlorate Aluminum chlorite Aluminum oxalate Aluminum sulfite Aluminum phosphate

Table 2

Zinc iodide Zinc chlorate Zinc chlorite Zinc oxalate Zinc sulfite Zinc phosphate

Table 2

Potassium iodide Potassium chlorate Potassium chlorite Potassium oxalate Potassium sulfite Potassium phosphate

Given the name, write the formula

1. Copper (I) chloride2. Copper (II) chloride3. Calcium hydroxide4. Calcium carbonate5. Ammonium sulfate

1. CuCl2. CuCl23. Ca(OH)2

4. CaCO3

5. (NH4)2SO4

Given the name, write the formula

6. Silver sulfate7. Lithium fluoride8. Iron (II) sulfate9. Sodium oxide10. Sodium nitride

6. Ag2SO4

7. LiF8. FeSO4

9. Na2O

10. Na3N

Assign WS I.

Name the compounds in your Lab Ionic Compounds on the

back of WS I.

Objective 7

Describe how covalent bonds form and the attractions that keep atoms together in molecules.

Table 1, slide 6

C-H In covalent bonding there is the sharing of

one or more electron pairs. There is NO ELECTRON TRANSFER!

The compound that forms stays together because the atoms that are bonding share the electrons to help obtain a stable electron configuration.

C-H Carbon is 1s2 2s2 2p2 it has four valence

electrons. Hydrogen is 1s1 and has one valence electron. Notice that if you put them together to make

CH4, carbon will have 8 electrons around it and is stable and each hydrogen will have one pair. That fills the 1s level for hydrogen and it too is stable.

Continue with the remaining covalent examples.

CH4 Dot Diagram

Polar bond Polar molecule

H2

Nonpolar bond Nonpolar molecule

NH3

Polar bond Polar molecule

Na2S

Ionic, not covalent. It is an exception. Draw showing electron transfer.

PH3

Polar bond Polar molecule

I2

Nonpolar bond Nonpolar molecule

CO

Polar bond Nonpolar molecule

CO2

Polar bond Nonpolar molecule Note: two double bonds formed

O2

Nonpolar bond Nonpolar molecule Double bond

SCl2

Polar bond Polar molecule

N2

Nonpolar bond Nonpolar molecule Triple bond

Terms:

A nonpolar bond is between like atoms. A polar bond is between different atoms. A nonpolar molecule results when the

same element is around the compound. A polar molecule forms when the

compound has “sides” or appears to be different all the way around.

 

Covalent Bonds

Single bond- the sharing of one electron pair.

Double bond- the sharing of two electron pairs.

Triple bond- the sharing of three electron pairs.

Covalent bonds occur to help each element attain an octet

C2H6

Polar bond Nonpolar molecule

C2H4

Polar bond Nonpolar molecule Double bond

C2H2

Polar bond Nonpolar molecule Triple bond

Lab Covalent Compounds.

Use the bag of atoms and plastic dots to help you to form the covalent compounds.

Objective 9

Name and determine the chemical formulas for molecular compounds.

Naming Covalent Compounds.

Typically covalent compounds are composed of two or more nonmetals combined.

To name the compound, say the name of the first element and use Greek prefixes to indicate how many of each element you have.

The second element ends in –ide.

The Greek prefixes are:

1 Mono-2 Di-3 Tri-4 Tetra-5 Penta-

6 hexa-7 Hepta-8 Octa-9 Nona-10 Deca-

Greek prefixes Never use mono on the first word, always use mono on the

second! Compound NameCO carbon monoxideCO2 carbon dioxideSO2 sulfur dioxideN2H4 dinitrogen tetrahydrideSO3 sulfur trioxideP2O5 diphosphorus pentoxide (drop the a in penta)

You try:

N2O3

PCl3SiO2

CCl4I2O7

BeH2

Answers

Dinitrogen trioxidePhosphorus trichlorideSilicon dioxideCarbon tetrachlorideDiiodine heptoxide (drop the a)Beryllium hydride

Properties of Covalent Compounds

1. Low melting point.2. Formed by the sharing of electron pairs.3. Nonconductor in the solid state, when

dissolved in water or when melted. Covalent compounds are non-electrolytes.

Volatile (have an odor or forms fumes). Example: Isopropyl alcohol (rubbing alcohol), mothballs.

Objective 10

Describe the structure of bonds in metals.

Metallic Bonding

Metal atoms achieve stable electron configurations by losing electrons.

But what happens if there are no nonmetal atoms available to accept the electrons?

The metal atoms become cations surrounded by a “pool of shared electrons.”

Metallic Bonding

A metallic bond is created by the attraction between the positive metal cation to the electrons lost.

These electrons are often referred to as “delocalized electrons.”

The metal is still neutral in charge, in effect, because the number of protons and electrons are still equal.

Metallic Bonding

Objective 11

Relate the properties of metals to their structure.

Properties of Metals

1. Conductor of electricity and heat.2. Ductile3. Malleable4. Luster

Objective 12

Distinguish between ionic, covalent and metallic bonding. How the bonds are formed, the forces that hold them together and properties.

Summary: Types of Bonds

Ionic Metal and nonmetal Large electronegativity difference > 1.67 Forms fomula units Transfer of electrons held together by

electrostatic attraction

Properties of Ionic Compounds

Solids are nonconductors Liquids, gases and aqueous solutions are

conductors. They are electrolytes High melting point and boiling point Low volatility Low vapor pressure

Summary: Types of Bonds

Covalent Two nonmetals combined Small electronegativity difference < 1.67 Forms molecules Sharing of one or more electron pairs

Properties of Covalent Compounds

Noncoductors of electricity Non-electrolytes Low melting and boiling points Volatile High vapor pressure

Summary: Types of Bonds

Metallic Composed of metal atoms Delocalized electrons are free electrons

among the cations Electron Sea Model

Properties of Metallic bonding

Conductors of heat and electricity High melting and boiling point Malleable Ductile Luster

The end.