Chemical BondingObjectives: Understand why compounds exist in nature. Indentify and compare the two classes of

compounds by their chemical and physical properties.

Identify and predict compound names and formulas by element’s location on the periodic table.

Illustrate chemical bonding between elements.

Periodic Trends: Review

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 180

20

40

60

80

100

120

140

160

180

200

Atomic Number vs. Atomic Radius

atomic number

ato

mic

ra

diu

s (

pm

)

Use graph to recall atomic radius trend across a period and down a group on the Periodic Table. Size of an atom influences an atom’s ionization and Electronegativity values.

Periodic Trends: Review

Ionization Energy:increase

Atomic Radius: decreases

*Electronegativity: increase*Electro

neg

ativity: decrease

Ion

ization

En

ergy: d

ecrease

Ato

mic R

adiu

s: increases

Electronegativity Review• Electronegativity: The degree of attraction atoms in a

compound have toward the bonded electrons. • Notice most noble gases do NOT have an electronegativty

value because they do not need to participate in chemical bonding-already stable.

Chemical Bonding Review1.Classify each compound below as ionic or

covalent.

a.KCl (Ionic: metal and non-metal)

b. CO (Covalent: 2 non-metals)

c. H2O (Covalent:2 non-metals)

d. MgCl2 (Ionic: metal and non-metal)

Metals vs. Non-metals

Chemical BondingIonic Bonding: Between a metal and a non-metal atom. Electronegativity difference between atoms is large. Transfer of valence electrons. Ionic Bond = Intramolecular Forces

Covalent Bonding: Between two non-metals. Electronegativity difference between atoms is small Share valence electron(s) Covalent Bond = Intramolecular Forces Covalent compounds are also called molecules.

Ionic Bonding Transfer of valence electrons from a metal

atom to a non-metal atom.

Creates a metal ion (cation) and non-metal ion (anion) that are held together by electrostatic attractive forces (chemical bond)

Chemical bonds are intramolecular forces.

Formation of Ionic Compounds

Ionic Bonding

Intramolecular Forces The chemical bonds within a single compound.

Lewis Dot StructuresLewis Dot Structures:

•Illustrates valence electrons

for an atom.

Place electrons (dots) around

the elements symbol using

cardinal direction.

• Do NOT pair electrons

up until you have to.

Element # of valence electrons

Lewis Dot Structure

Na 1

Mg 2

Si 4

S 6

He 2

Lewis Dot Structures

http://www.roymech.co.uk/Related/Chemistry/Lewis_dot_structure.html

Ionic Bonding (Lewis Dot Transfer)

Metal (Lewis Dot)

Non-metal(Lewis Dot)

Ionic Bonding(Lewis Dot Transfer)

Ionic Cmpd Chemical Formula

Chemical Name (name of the ions)

Chemical Bonding1. Classify each compound below as ionic or covalent.

a. CO2 b. AlCl3 c. Mg3P2 d. H2 e. H2O

C I I C C

2. a. Which compounds above were formed from the transfer of ve-? All ionic compounds

b. Which compounds above were formed from the sharing of ve-? All covalent compounds

3. For those compounds that share ve-, identify which compounds have polar bonds and which have non-polar bonds. Covalent compounds that do NOT share bonded electrons equally. (CO2 and H20)

Covalent Bonds

Prentice Hall KY Teacher Express, 2008

Polar Bonds: Where atoms do NOT share bonded electrons equally. Usually 2 different elements making up the bond. Ex. N-----ONon-Polar Bonds: Where atoms share bonded electrons equally. Same elements. Ex. O-----O

Ionic Compounds

The overall charge on any ionic compound is always zero.

The ratio of metal to non-metal ions has to equal zero

Ionic Compound Nomenclature

How do scientist name ionic compounds?

Binary Ionic Compounds: Simplest compounds, composed of two ions (cation and the anion)

Name the cation and the anion.

*Use flow-chart to help you name each ion in the compound.

IonsOxidation number: The charge on an atom.

Some elements have a fixed oxidation number.

Primarily representative elements (tall groups on periodic table)

Some elements have multiple oxidation numbers.

Primarily transitional elements (short, middle groups on the periodic table).

Naming Cations: Metals Fixed Oxidation Number ( fixed charge)

- Simply the name of the metal- Ex. Al3+ : aluminum ion

Multiple Oxidation Numbers (multiple

charges)- Name of metal and roman numeral to identify

what charge is being used. - Fe2+: iron (II) ion

Fe3+: iron (III) ion

Oxidation Numbers and Periodic Table

Naming Anions: Non-metals Non-metals only have a single oxidation #

(charge) when becoming an anion.

It is the root word of the non-metal with an –ide ending.

Ex. Br 1- = Bromide

Ex. P3- = phosphide

Naming Ionic Compounds*Use flow chart to name ionic compounds*

1. KF : potassium fluoride

2. Ca3P2 : calcium phosphide

3. CuBr2 : copper (II) bromide

4. FeN : iron (III) nitride

Naming Ionic Compounds BaCl2: barium chloride

Mn3P2: manganese (II) phosphide

Ag2O: silver oxide

CaBr2: calcium bromide

Chemical Formula of Ionic Compounds

1. Write the symbol and charge for the cation and the anion.

2. If charges balance, then the ions are one to one in the formula.

3. If charges do not balance, then use the criss-cross method to establish the correct ratio of ions (subscripts) so they do balance out in the formula.

Determine the Chemical Formula

1. Aluminum Phosphide: Al2P3

2. Magnesium Chloride: MgCl2

3. Iron (III) Sulfide: Fe2S3

4. Chromium (II) Oxide: CrO

5. Nickel (II) Bromide: NiBr2

Types of Ions Monatomic Ions :

1 element makes-up

the ion.

Polyatomic Ions:

2 or more elements

make-up an ion.

Mono or Poly Ions?a. Na 1+ : mono

b. (S04)2- : poly

c. Cl 1-: mono

d. (PO3)3-: poly

Ionic Compoundsa. Li (OH): lithium hydroxide

b. Fe2(CO3)3 : iron (III) carbonate

Sodium Sulfate: Na2(SO4)

d. Chromium (II) Phosphate : Cr3(PO4)2

Covalent Compounds Covalent compounds = molecules When naming covalent compounds prefixes

are primarily used. *Use flow chart*

Prefixes: Mon(o)=1 atom Hexa = 6 atoms Di= 2 atoms Hepta= 7 atoms Tri= 3 atoms Octa= 8 atoms Tetra= 4 atoms Nona= 9 atoms Penta= 5 atoms Deca= 10 atoms

Covalent Compounds1. Chemical name of covalent compounds

a. CO2= carbon dioxide

b. P2O5 = diphosphorus pentoxide

c. O2= oxygen

2. Chemical formula of covalent compounds.

d. dihydrogen monosulfide = H2S

e. dinitrogen trioxide= N2O3

f. bromine= Br2

Chemical Compounds

I can name, predict, and critique chemical compounds.

I can identify, interpret, and investigate properties of chemical compounds.

Chemical Compounds Venn Diagram

Ionic Compounds Covalent Compounds

Chemical CompoundsObjectives:• Use your chemical compound venn diagram to

establish a hypothesis for your physical properties lab.

Physical Properties Lab

Electrical Conduction Lab:

Which samples do you think will conduct electricity?

Crystal Structures Lab:

Which of the samples do think will grow crystals the fastest? the slowest?

Physical Properties Lab

Electrical Conduction Lab:

Which samples do you think will conduct electricity?

Crystal Structures Lab:

Which of the samples do think will grow crystals the fastest? the slowest?

Electrical Conduction Lab Data

Grp #

Tap H2O

DeionizeddH2O

Salt soln.(NaCl)

Sugar Soln.C6H12O22

VinegarSoln.C2H4O2

BakingSodaSoln.NaHCO3

BoraxNa3BO3

1

2

3

4

5

6

7

Yes (Y) if substance conducted electricity, No (N) if did not.

Tap Water• Ground water produced the passageways at Mammoth Cave. • In so doing , water picks up many contaminants. One common contaminant is limestone residue. Why tap water conducte electricity.

Properties of Chemical Compounds

Which kind of compounds conduct electricity best?

Properties of Ionic Compounds

Ionic compounds can conduct an electric current when melted or dissolved in water.

7.2

Properties of Chemical Compounds

Why can’t chemical compounds in the solid state conduct electricity?

7.2

Properties of Chemical Compounds The orderly arrangement of atoms/ions

produces beautiful crystalline structure. Which compound from the lab produced crystals

faster/slower?

7.2

Salt Crystal Lattice Na+ and Cl- ions produce a solid, repeating 3-D

structure called a crystal lattice.

7.2

Sugar Crystal Lattice Sugar molecules will produce a crystal

lattice, but it will occur slower. Weaker attractive forces (partial charges)

between molecules.

http://www.michigansugar.com/images/ag/production/th_med_crystals.jpg

http://iscience.ru/wp-content/uploads/2008/12/sugar-molecule-02.jpg

o oo o

C C C C

Covalent Bonds

Prentice Hall KY Teacher Express, 2008

Polar Bonds: valence electrons shared unequally between atoms in a molecule. Non-Polar Bonds: valence electrons shared equally between atoms in a molecule.

Electronegativity Values

Properties of Ionic Compounds

Chemical Compounds Melting Point (oC) Boiling Point (oC)

Cr2O3 2,266 4,000

SrF2 1,470 2,489

CCl4 -22.9 76.6

CH4O -97.8 64.7

Chemical Compounds Article

• From the table below, what can be concluded about the differences in melting and boiling points of chemical compounds? Ionic compounds have higher melting and boiling points.

Properties of Chemical Compounds

Collection of Ionic Compounds Collection of Covalent Compounds

• Why do ionic compounds in general have higher melting and boiling points? stronger attractive forces between ions

Properties of Chemical Compounds

Ionic Compounds are primarily solids at room temperature. Ex. salt

Molecules can be a solid, liquid, or gas at room temp. Examples:

.

O2 and CH4 (C8H18) (C8H8)

Properties of Chemical Compounds

Collection of Ionic Compounds Collection of Covalent Compounds

• Which type of compound do you think is more brittle when stress is applied to it?

Properties of Ionic Compounds

Ionic crystals are brittle when stress is applied. Repulsion increases when similar ions are force

together.+

++ + +

+

+

+

+

+

--

-- -

--

-

http://www.chemguide.co.uk/atoms/structures/ionicstruct.html

Properties of Molecules Molecules are more resilient (durable) than

ionic compounds. Why?

http://www.chemguide.co.uk/atoms/structures/ionicstruct.html

Chemistry

Drawing molecular structures and identify polar bonds.

Chemical Structure of Covalent Compounds

Non-metals atoms share valence electrons to reach stability. (Octet Rule)

Types of covalent bonds between two atoms:

a. Single Bond (share 2ve-)

b. Double Bond (share 4 ve-)

c. Triple Bond (share 6 ve-)

Drawing Molecular Structures1. Draw Lewis Dot Structures for each element in the

molecule.2. Calculate the total number of valence electrons in the

molecule.3. Share unpaired valence electrons between atoms. Each bond represents a pair of shared electrons.Ask: How many unpaired electrons can each atom share

with one another? Determines the # of bonds between atoms.

4. Add lone pairs to atoms in the molecule if needed. 5. Check to make sure each atom is stable in your molecular

structure (Octet Rule) and all valence electrons are accounted for.

Octet Rule Exception:Hydrogen

Molecules: Lewis Dot Sharing

Molecular Formula

Lewis Dot Sharing Molecular Structure

Polar Bonds

ChemicalCompoundsReview

Ionic Compounds: Transfer of valence electrons.Usually a metal and a non-metal ion.

Covalent Compounds: Sharing valence electrons.Consists only of non-metals.

Ionic vs. Covalent Compounds

Covalent Compounds Illustrate and model covalent bonding with

Lewis Dot and Molecular structures.

Illustrate and predict which molecules are polar.

Identify and predict the types of intermolecular forces between molecules in the liquid and solid state.

Molecular Geometry Shape of the molecule in 3-D space.

VSEPR Theory:

-(Valence Shell Electron Pair Repulsion)

-How bonds and lone pairs are arranged around the central atom in a molecule to minimize electron repulsion.

Molecular Geometry Using the VESPR hand-out and the

molecular model kit, classify each of these molecules.

Molecules Molecular Structure

MolecularGeometry Name;Bond Angle

Polar or Non-polar Molecule

NCl3

CBr4

SCl2

SiO2

PF5

Electronegativity Values

VSEPR Theory(Valence Shell Electron Pair Repulsion)

liakatas.org

Polar Molecules

Polar molecules: One end of the molecule is partially positive and the other end is partially negative.

Also called dipole molecules.

False: All molecules that have polar bonds are classified as polar molecules.

Molecules and Polarity

ieshermanosbilingual.blogspot.com

en.wikipedia.org

3dchem.com

P

F

F

F

..O

H

H

Polar vs. NonPolar Molecules

Molecules Molecular Structure

MolecularGeometry Name;Bond Angle

Polar or Non-polar Molecule

NCl3 trigonal pyramidal(109.5)

CBr4 Tetrahedral (109.5)

SCl2

Bent (109.5)

SiO2 Linear (180)

PF5 Trigonal bypyramidal(some 120; some 90)

Polarity of Molecules

What is the point of classifying molecules as polar or non-polar?

Predict the degree of solubility for a molecule.

Solubility: Like dissolves like.

Predict the type of intermolecular forces holding molecules together in the solid and liquid states.

Intermolecular Forces

itl.chem.ufl.edu

Types of Intermolecular Forces

1.Dipole Forces :• Attraction b/w polar molecules• Partial charges oppositely

attract

Prentice Hall: Chemistry

Types of Intermolecular ForcesHydrogen Bonds :• Very strong dipole force.

Pre-resquiste for H bonding to occur: • H must be covalently bonded to a very

electronegative element (N, O, F).

Prentice Hall: Chemistry

Types of Intermolecular Forces

• 3. London Dispersion Forces:• Caused by random motion of electrons in each

bonded atom. • Temporary dipole forces.• Occur in non-polar and polar molecules.

elmhurst.edu

I

I

Chemistrya. What is the chemical name of your molecule?

b. Draw its molecular structure (use your rules)

c. Identify if the bonds are polar or non-polar bonds. Explain your answer.

d. Does your molecule have single, double or triple bonds? Explain your answer.

Bell Ringer: Molecules1. a. Draw the molecular structure of NBr3

b. Identify its geometrical shape?

c. Is it a polar or non-polar molecule?

d. Would it be soluble in water? Explain.

e. What type of intermolecular force(s) would

exist between NB3 molecules in the solid or liquid state?

Metallic BondingWhat are some properties of Metallic Bonding?

Metallic Bonding