CP Chemistry Conceptual
Review Sheets for Final Exam
Name ___________________________________
Jaeger
Date _____________
Period ________
Chapter 9 Polarity
Octet Rule In forming compounds, atoms tend to achieve the electron configuration of a noble gas (octet = set
of eight). (Atoms of metals tend to lose electrons and nonmetals gain electrons (or nonmetals share electrons in
covalent bonds) to achieve noble gas configuration.)
1) Which pair of atoms would most likely form an ionic bond (remember metals + nonmetal = ionic bond)
a) Na/Al
b) Na/F
c) N/N
d) H/O
2) Valence electrons are ______________________________________________________________________
3) Elements in the same ______________________ usually have the same # of valence electrons.
4) How many valence electrons does an atom of the following groups in the periodic table have?
IA ____ IIA _____
IIIA _____ IVA _____ VA ______ VIA _____
VIIA _____ VIIIA _____
5) The octet rule states that __________________________________________________________________
_________________________________________________________________________________________
Covalent bonds: Nonmetal atoms form covalent bonds when they share electrons to form an octet.
Electronegativity (EN)
is the tendency of an atom to attract the electrons inside a
chemical bond (when it is chemically combined with atoms of
another element). Starting with Fluorine (highest EN = 4.0) the
EN decreases in the periodic table from top to bottom and right
to left (Cesium 0.7 lowest).
Electronegativity is used to predict the type of bonding formed.
When F and Cs combine, Cs completely loses the electron “tugof-war” and forms a positive ion, and F becomes a negative ion
⇒ ionic bond. If the electronegativity difference (∆
∆EN)
between the two combining atoms is relatively small the bond
will be covalent.
8) Define Electronegativity (EN) _______________________________________________________________
__________________________________________________________________________________________
9) Element with the highest EN _______, lowest EN _______; in general, metals have a __________________
EN than nonmetals.
10) In the periodic table to the right, draw two arrows to indicate in which
directions (up or down and left or right) the electronegativity of elements
decrease.
11) ∆EN is short for ___________________________________________
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Review Sheets for Final Exam
CP Chemistry Conceptual
∆EN
medium (0.5 – ≈ 1.9)
polar covalent
small (0 – 0.4)
nonpolar covalent
Jaeger
large (≈
≈2.0 – 3.3)
ionic
12) For the following pairs determine, which type of bond each will most likely form: (see Table on page 1)
a) nonpolar covalent
b) polar covalent
c) ionic
H/F _________________
F/F _________________
Na/F ________________________
N/N _________________
N/H _________________
Li/N ________________________
Polar Bonds and Molecules
When covalent bonds join identical atoms, the bonding electrons are
shared equally and the bond is nonpolar. When the atoms in a bond have
different electronegativities, the bonding electrons are shared unequally
and the bond is polar. A dipole is created similar to a magnet with a
slightly positive and negative end, indicated by δ+ and δ- (delta) or an
arrow pointing from + towards – (towards the higher EN).
In a polar molecule one end is slightly positive and one end slightly
negative (e.g. HCl, H2O). CO2 is a nonpolar molecule even though it has
two polar bonds, because they lie along the same axis in opposite
direction and cancel each other out.
but
Dipoles cancel here
14. For each of the following bonds
(10pts)
a) determine the electronegativity of each atom involved b) calculate ∆EN c) decide if the bond is ionic
(∆EN 2.0 or larger), polar covalent (∆EN = 0.5 – 1.9) or nonpolar covalent (∆EN 0.4 or less)
d) symbolize the dipole in polar covalent bonds (only) with an arrow as well as the ∂+ and ∂- symbols., for
ionic bonds indicate where the positive and negative charge(s) will be (+, -).
example
d) Bond
a) EN each atom
b) ∆EN of the bond
c) Nonpolar, polar or
ionic
d) Bond
∂+
∂-
H-F
2.1
B-H
Na-F
K-O
C-Cl
4.0
1.9
Polar covalent
Br-Br
a) EN each atom
b) ∆EN of the bond
c) Nonpolar, polar
or ionic
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CP Chemistry Conceptual
Review Sheets for Final Exam
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15. For each of the following molecules determine if it is nonpolar or polar: a) Determine the dipole (value and
direction) for each bond. b) Decide if the different dipoles add up or cancel each other out.
(CCl4, AsCF, HF, ClBr, CO2, SeCl2)
(3pt each)
Intermolecular forces are weak attractions between molecules and
determine in part whether a covalent compound will be a solid, liquid, or
gas.
Formation of drops and surface tension are the result of
intermolecular attractions. Hydrogen bonds are a type of intermolecular
forces, e.g. between water molecules, in DNA, or when dissolving sugar in
water.
Chapter 13 Water and Solutions
Polarity and hydrogen bonds (interaction between the hydrogen atoms (δ+)
and free electron pairs of the oxygen atoms (δ-)) are responsible for many of
the unusual physical properties of water:
♦ Water has a high boiling point for its small molecular size.
♦ Density: Most substances are more dense as solids than as liquids, but water has its highest density
(“heaviest”) at 4°C (still liquid). Ice is less dense than water, thus floats on lakes and ponds, helping fish to
survive the winter. On the other hand pipes and bottles break when water inside expands when turning into ice.
Rocks also erode faster (crumble) when trapped water freezes.
♦ Drops of water are formed because of surface tension, which is a force needed to overcome intermolecular
attractions and break through the surface of a liquid or spread the liquid out.
♦ Capillarity (or capillary action) is the rising of a liquid in a narrow tube.
♦ Water has a very high specific heat. (Specific heat is the amount of heat needed to raise the temperature of
1g of a substance by 1°C.) A lot of energy is needed to heat up water (endothermic), and cooling down water
releases a lot of energy (exothermic). This affect’s the earth’s climate, e.g. ocean climate: summers are less hot
and winters are less cold in areas close to the ocean or big lakes.
♦ Water is a great solvent for polar molecular and ionic compounds, sometimes called “the Universal solvent”.
Ionic compounds (like NaCl) dissociate in water, meaning the cations and anions are separated.
Like dissolves like. Polar solvents, such as water, tend to dissolve polar and ionic compounds (solutes like
sugar or NaCl), but not nonpolar ones (like wax or oil).
Temperature affects solubility. Generally, the solubility of solids increases with increasing temperature.
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CP Chemistry Conceptual
Review Sheets for Final Exam
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1) Polar molecules have a dipole. Explain and use HF to show two ways to symbolize the dipole (→ or δ+δ-).
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
2) Why is CO2 a nonpolar molecule even though it has two polar bonds?
__________________________________________________________________________________________
3) Water is a bent molecule. If it were linear it would be a nonpolar rather than a polar molecule. Explain:
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
4) What are intermolecular forces?
__________________________________________________________________________________________
__________________________________________________________________________________________
5) Are hydrogen bonds covalent bonds or intermolecular forces? _____________________________________
6) Which bonds are stronger: Covalent bonds or intermolecular forces? ________________________________
7) Do intermolecular forces influence the melting and boiling points of molecular compounds? _____________
8) Give two more examples in which hydrogen bonds play an important role: ___________________________
9) List at least 6 properties of water that are caused or influenced by intermolecular forces
__________________________________________________________________________________________
__________________________________________________________________________________________
10) At what temperature does water have its highest density? ________________________________________
11) What is….
…surface tensions?__________________________________________________________________________
__________________________________________________________________________________________
… specific heat _____________________________________________________________________________
__________________________________________________________________________________________
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Review Sheets for Final Exam
CP Chemistry Conceptual
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…capillarity _______________________________________________________________________________
a) water
b) mercury
12) Draw how the surfaces curve in a graduated cylinder for liquid water and mercury
13) Which liquid forms better drops: Water or isopropanol? __________________
14) Which needs most energy when heated from 10°C to 20°C?
a) aluminum
b) ethanol
c) water
d) all the same
15) What liquid is called the Universal Solvent? ____________________________
16)
Wordbank:
____ 1. Solution
a) Homogeneous mixture (example salt water)
b) Dissolved particles in a solution (example salt)
____ 2.
Solute:
c) The dissolving medium in a solution (example water)
____ 3.
____ 4.
Solvent
Concentration
d) a measure of the amount of solute that is dissolved in a
given quantity of solvent (in a solution).
____ 5.
____ 6.
Dilute solutions
concentrated solutions
e) contain only a low concentration
f) contains a high concentration of solute.
____ 7.
Saturated solutions
____ 8.
Molarity
g) contain the maximum amount of solute in a given solvent
at a given temperature and pressure.
h) concentration expressed in moles/liter
M=mol/L
17) Why does oil not mix with water, but sugar and NaCl are easily dissolved in water? ___________________
__________________________________________________________________________________________
18) At what temperature can I dissolve the most sugar in my tea?
A) 0 °C
B) 4 °C
C) 75 °C
D) 100 °C
Chapter 14,15 Acids and Bases
Acids and Bases are considered opposites, when reacting with each other (neutralization), they produce water
and a salt. They both can be strong or weak electrolytes in aqueous solution (conduct electricity), and cause
indicators (certain chemical dyes) to change color.
Acids have several distinctive properties and they are in many common items. They give foods a tart or sour
taste (vinegar contains acetic acid, citrus fruits citric acid, tea tannic acid, vitamin C is ascorbic acid etc.).
Acids (HA) have at least one acidic hydrogen and produce hydronium ions (H3O+) when dissolved in
water. “Acids release H+ ions.”
H2O + HA
H3O+ + Aexample
H2O + HCl
H3O+ + ClMany metals, such as zinc and magnesium, react with aqueous solutions of acids to produce hydrogen gas.
M + x HA
MAx + n H2
example
Mg + 2 HCl
MgCl2 + H2
Acids (HA) react with compounds containing hydroxide ions OH (a base) to form water and a salt.
MOH + HA
MA + H2O
example
NaOH + HCl
NaCl + H2O
+
Acidic hydrogen atom is one that can be transferred to water as H (written at first in the formula of the acid). It
is often covalently bonded to a very electronegative element, upon ionization the electron is completely
transferred onto the neighboring atom.
Monoprotic acids contain only one acidic hydrogen,
example HCl
H+ + Cl5
Review Sheets for Final Exam
CP Chemistry Conceptual
Diprotic acids contain two acidic hydrogens,
Triprotic acids contain three acidic hydrogens,
Jaeger
2H+
3H+
example H2SO4
example H3PO4
+ SO42+ PO43-
Bases Aqueous solutions of bases taste bitter and feel slippery. Simple bases are metal hydroxides such as
NaOH. NaOH (lye) is used as a drain cleaner. Milk of magnesia (Mg(OH)2 suspension in water) is an antacid.
Ammonia (NH3), a cleaning reagent, and Lime (CaO), used to neutralize acidic soil, are also bases.
Bases (B) are compounds that produce hydroxide ions (OH-) when dissolved in water. Ionic hydroxides are
bases because their ions dissociate in water. Covalent bases (like NH3) ionize when water transfers a hydrogen
ion (H+) to the base, leaving hydroxide ion (OH-) behind. “Bases release OH- ions or catch H+ ions.”
MOH
B + H2O
M+ + OHBH+ + OH-
example
example
Na+ + OHNH4+ + OH-
NaOH
NH3 + H2O
Bases also react with acids to form water and a salt (neutralization reaction, combining H+ with OH- to H2O).
(Metal hydroxides from group 1A and 2A are strong bases (LiOH, NaOH, Ca(OH)2); from group 3A or Bgroups are weak bases. Ammonia, NH3 is a weak base.
Strong and weak acids and bases
A strong acid or base is completely (or almost completely) ionized in water.
A weak acid or base is only slightly ionized in water.
(definition for concentration see page 5, 16): 4 answer d))
Anhydrides
Nonmetal oxides form acids when they react with water Acidic anhydrides
Metal oxides form acids when they react with water Basic anhydrides
HCl or NaOH
Vinegar or NH3
CO2, SO3, NO2 etc.
CaO, K2O, etc.
Hydrogen Ions and Acidity
The self-ionization of water occurs only to a very small extent; in pure water at 25 °C, the concentration of
hydrogen ions [H+] and the concentration of hydroxide ions [OH-] is each only 1.0 x 10 –7 M = 0.0000001 mol/l.
As long as both concentrations are equal in value, the solution is neither acidic nor basic, it is a neutral solution.
[H+] = [OH-]⇒ neutral
[H+] > [OH-] ⇒ acidic (more H+)
[H+] < [OH-] ⇒ basic (more OH-)
+
-14
2
[H ] x [OH ] = 1.0 x 10 M = Kw
In aqueous solutions the product is always equal 1.0 x 10-14
The pH concept
pH = -log [H+]
If [H+] = 1.0 x 10-7:
pH = - log (1 x 10 –7) = 7.0
Acidic solution: pH < 7.0 [H+] greater that 1 x 10 –7
Basic solution: pH > 7.0 [H+] less that 1 x 10 –7
neutral solution: pH = 7.0 [H+] equals 1 x 10 –7
pOH = -log [OH-]
pH + pOH = 14
pOH = 14 – pH
1) Assign:
a) acid,
b) base,
pH = 14 – pOH
c) acid and base (both)
1. Releases H+ ions (also called protons) _____ 2. Produce hydroxide ions (OH-) ______
4. Neutralizes acids _____ 5. Neutralizes bases_____
8. Change colors with indicators _____
11. Ammonia NH3 _____
6. Slippery feel ___
9. Milk of magnesia, Mg(OH)2 _____
12. Aspirin and Vitamin C _____
3. HCl _____
7. Tart or sour taste _____
10. Bitter taste ______
13. Vinegar _____ 14. NaOH _____
15. Electrolytes (conduct electricity) ____ 16. React with Zinc to form Hydrogen gas _____ 17. Fruits ____
18. Tomatoes _____
2) What is a(n)…
19. monoprotic, diprotic or triprotic _____
20. Contains acidic hydrogen _____
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CP Chemistry Conceptual
a) hydronium ion _____________
Review Sheets for Final Exam
b) proton _________________
Jaeger
c) hydroxide ____________
3) a) What kind of acids would you expect to find in food items? (weak or strong) _______________________
b) Give three examples of acids found
in beverages, fruits or other food items. _______________________________________________________
4) Name three strong bases (or give formulas) ____________________________________________________
5) What is the difference between monoprotic, diprotic and triprotic? __________________________________
__________________________________________________________________________________________
6) Give an example of a neutralization reaction ____________________________________________________
7) a) What are anhydrides? ____________________________________________________________________
b) What are the two types of anhydrides and how do they react differently? _____________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
c) Give two examples each. ___________________________________________________________________
8) Which basic anhydride (base) is used to neutralize acidic soil? _____________________________________
9) Explain the difference between a strong and a weak acid and give examples __________________________
__________________________________________________________________________________________________
__________________________________________________________________________________________________
10) Name three acids (or formula) _____________________________________________________________
11) Name three bases (or formula) _____________________________________________________________
12) Which groups of metal hydroxides are considered weak bases? ____________________________________
13) A solution that resists changes in pH
if small amounts of acids or bases are added is called ____________________________________________
14) Define electrolyte ________________________________________________________________________
___________________________________________________________________________________________________
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Review Sheets for Final Exam
CP Chemistry Conceptual
Jaeger
15) Which solution is acidic, neutral or basic?
pH 0- 6.9
_____________
pH 7
[H+] > [OH-] _____________
______________
pH 7.1 – 14 ___________
[H+] = [OH-] ____________
[H+] < [OH-] ___________
16) pH + pOH = 14
If the pH is 7.0, the pOH is ________,
If the pH is 7.9, the pOH is ________
If the pOH is 9.5, the pH is ________,
If the pOH is 11.0 the pH is ________
If the pH is 13.9, the pOH is ________,
If the pH is 1.5, the pOH is ________
17) pH = -log [H+]
pOH = -log [OH-]
If the pH is 5, [H+] = _______
if the pOH is 5, [OH-] is _______
If the pH is 13, [H+] = ______
if the pOH is 13, [OH-] is _______
18) a) Acidic
b) basic
c) neutral
pH 1.0 ____
pH 5.5 ____
pOH 1.0 ____ pOH 5.5 ____
pH = 14 - pOH
pH 7.0 ____
pH 13.0 ____
pH 14.0 ____
pOH 7.0 ____
pOH 13.0 ____
pOH 14.0 ____
19) Complete the table
Hydrogen ion
Concentration
[H+]
Hydroxide ion
Concentration
[OH-]
pH value
pOH value
Acidic, basic
or neutral?
1 x 10-2
3
1 x 10-5
7
1 x 10-10
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