Download Webquest Review - Harrison High School

Webquest Review
Go to http://sites.google.com/site/ionicandcovalentbonding/ or go to my blog and
click link for google website, then bonding.
Part One: View the Concepts and Skills page.
1. When looking at an ionic compound formula, what should I be able to do?
Recognize compound as being ionic, write the correct formula, analyze to
determine number of each type of ion in structure; realize it has a high BP,
high MP, will probably dissolve easily, will conduct electricity when
dissolved in solution
2. Lewis dot structures will be needed to answer many test questions. List a
few concepts that require a Lewis dot structure.
Every covalent compound or polyatomic ion needs a Lewis structure to
demonstrate the bonding electrons, the shape of the species, and its
polarity.
Part Two: View “How can I tell the difference between ionic and covalent
compounds?”
3. Summarize the difference between ionic and covalent compound
composition.
Ionic compounds are composed of a metal (or NH4+) and a nonmetal,
bonding by a transfer of electrons which results in an electrostatic
attraction keeping the charges together in an ionic bond. Covalent
compounds have 2 or more nonmetals bonded by sharing of electrons
which includes no ions.
Part Three: Ionic Compounds
A: View “Formation of Ions and Ionic Bonds.”
4. Explain how Mg3(PO4)2 is a neutral compound.
There are three Mg2+ ions attracted to two PO43- ions which holds the ions
together by an ionic bond. Since there are three 2+ ions and two 3- ions,
the charges balance out giving a net charge of zero.
5. How and why does aluminum form a cation?
Aluminum has three valence electrons. It is easier for aluminum to lose
those three electrons to attain an octet in the 2nd energy level than it is for
aluminum to gain five electrons. As aluminum loses the three valence
electrons, it is left with a 3+ charge on the ion.
B: View “Writing and Naming Ionic Compounds.”
6. Write formulas for the following:
a. magnesium nitride
Mg3N2
b. iron (II) hydroxide
Fe(OH)2
c. ammonium sulfide
(NH4)2S
d. calcium chlorate
Ca(ClO3)2
7. Name the following:
a. KNO3
potassium nitrate
b. CuSO4
copper (II) sulfate
c. AgBr
silver bromide (no Roman numeral needed)
d. CoPO4
cobalt (III) phosphate
C: View “Analyzing Ionic Compounds: Higher-level Thinking.”
8. How many carbonate ions are in CaCO3?
In this formula, there is one Ca2+ ion and one CO32- ion, by inspection.
9. If GdO exists and Dy(NO3)4 exists, what is the formula for gadolinium
nitrate?
In GdO, Gd must take a +2 charge to balance out the -2 on the oxygen
ion. When you combine Gd2+ and NO31-, you have Gd(NO3)2.
Part Four: Covalent Compounds
A: View “Writing and Naming Covalent Compounds.”
10. Name the following:
a. NF3
nitrogen trifluoride
b. SiO2
silicon dioxide
c. N2O5
dinitrogen pentaoxide
d. C3H8
tricarbon octahydride
11. Write formulas for the following:
a. dichlorine heptasulfide
Cl2S7
b. carbon monoselenide
CSe
c. silicon tetrabromide
SiBr4
d. phosphorus trichloride
PCl3
B: View “Drawing Lewis dot structures.”
12. Draw all of the resonance structures for the nitrate ion.
There are three resonance structures for nitrate, moving the double bond
to each of the oxygens (DRAW)
13. How many lone pairs of electrons exist in sulfur dioxide?
In sulfur dioxide, there is sulfur in the middle, double bonded to one
oxygen, single bonded to the other. There is one lone pair on sulfur.
There are 2 lone pairs on the double bonded oxygen and three lone pairs
on the single bonded oxygen. (DRAW)
C: View “VSEPR – Valence Shell Electron Pair Repulsion.”
14. How many areas of high electron density surround the central atom in
NH3?
There are 4 electron density sites on the nitrogen.
15. What is the molecular shape of SO3 molecule? The shape of a sulfur
trioxide molecule would be trigonal planar as it is an AX3 molecule.
16. Why is water a bent molecule? Water consists of an oxygen atom, single
bonded to two hydrogen atoms. There are two lone pairs of electrons on
oxygen. This gives oxygen 4 electron density sites and makes it fit the
model AX2E2. All species that fit this scheme are bent with 105.5 bond
angle.
D: View “Electronegativity Difference and Polarity.”
17. Is silicon tetrafluoride a polar molecule? Draw the structure.
SiF4 is nonpolar. It has four identical bonds in a symmetrical molecule.
The polar bonds cancel each other out, leaving a nonpolar structure.
18. Is ammonia (NH3) a polar molecule? Draw the structure.
Ammonia is a polar molecule. When you draw it, there is a lone pair of
electrons on nitrogen. Lone pairs on the central atom distort the symmetry
of the species and cause it to be polar.
19. Is carbon dioxide a polar molecule? Draw the structure.
CO2 is nonpolar. You have two oxygens, each double bonded to the
carbon. These two identical bonds in a symmetrical species, pull in equal
yet opposite directions, cancelling each other out.
E: View “Intermolecular Forces.”
20. Explain why magnesium chloride should dissolve in water.
Magnesium chloride is an ionic compound composed of a cation and two
anions. Most ionic compounds with charges are easily pulled into solution
with water which is polar (partial charges).
21. Which of the following would be the most difficult to boil: H2O, CH3Cl, CO2
Why? First, draw the Lewis structures. When you do, you see that H2O
and CH3Cl are polar molecules. CO2 is nonpolar. The only forces that
can exist between nonpolar species are London dispersion forces, which
are very weak. Accordingly, CO2 will have a low boiling point. CH3Cl is
polar and will have dipole-dipole interactions between molecules. That
means CH3Cl will be harder to boil than CO2. H2O has H bonded to O and
it’s polar. When you have species with H bonded to F, O, or N, hydrogen
“bond”ing sets up between the molecules. Hydrogen bonding is the
strongest intermolecular force thus requiring the most energy to separate;
therefore, water is hardest to boil of these substances.
22. Carbon tetrachloride experiences London dispersion forces. Why?
CCl4 is a nonpolar molecule which can be determined by drawing the
Lewis structure. The only forces of attraction/repulsion between nonpolar
molecules are London dispersion forces.
F: View “Naming and Writing Formulas for Acids.”
23. Name the following acids:
a. H2CO3
carbonic acid
b. H2S
hydrosulfuric acid
c. H3PO3
phosphorous acid
d. H3P
hydrophosphoric acid
24. Write the formula for the following acids.
a. Acetic acid
HC2H3O2
b. Hydrochloric acid
HCl
c. Nitrous acid
HNO2
d. Nitric acid
HNO3
Part Five: Comments/Suggestions
Rate the website according the following areas. 1 = unhelpful; 5 = very helpful
Difference between ionic and covalent page
Forming ions and ionic bonds page
Naming and writing formulas for ionic page
Analyzing ionic compounds page
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Writing and naming covalent page
Drawing Lewis dot structures page
VSEPR page
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Electronegativity Difference & Polarity page
Intermolecular Forces page
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Naming and Writing Formulas for Acids page 1
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