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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