Fall 2008 Final Exam Review
Answer Key
Scientific Method
Know the difference between:
Hypothesis – A testable observation seen in nature
theory – An explanation supported by many experiments
law – an observation seen in nature
Accuracy/Precision – looking at measurements
Accuracy – how close a set of measurements is to the published standard.
Precision – how close a set of measurements is to each other.
Matter
What is the formula for density? Density = mass/volume
What is the density of water ? 1.00 g/ml If equal amounts of water, ethylene glycol
(density = 1.11 g/mL, and butane (density = 0.599 g/ml), were mixed in a jar, which
would be on top? On bottom? Top – butane, middle – water, bottom – ethylene glycol
Be able to calculate density by using the water displacement method to determine
volume. Final volume – initial volume = volume of object. Use this in the density
formula
Complete the chart below:
State
Definition – mention shape, volume,
compressibility, etc . . .
Solid Definite shape and volume.
Incompressible. Rigid structure. Atoms are
close together.
Liquid Definite volume only, Incompressible.
Flowing structure. Takes the shape of its
container. Atoms slide past each other.
Gas
No definite shape or volume.
Compressible. Takes the shape & volume
of its container. Particles are “far” apart
from each other.
Relate state to the Kinetic
Theory
Slowest movement out of
all three and thus the
lowest energy.
Particles are traveling at a
faster rate than solids thus
the kinetic energy of a
liquid is higher than that of
a solid.
Highest kinetic energy.
Fast moving particles.
List at least four types of evidence that a chemical change has taken place:
1. precipitate production
2. hue color change (ex: clear to red)
3. temperature change
4. gas production (bubbles are produced)
Know the difference between physical properties & chemical properties.
Know the difference between homogeneous vs. heterogeneous
Homogenous – the same throughout – pure substances, H2O, solutions – sweeten tea
Heterogenous – NOT the same throughout – vegetable soup – sugar & sand mixtures
Fall 2008 Final Exam Review
Atomic Structure
Fill out the following chart:
Subatomic particle
Charge
proton
neutron
electron
Relative Mass
(amu)
1
1
1/1840
+1
0
-1
Location
Inside nucleus
Inside nucleus
Outside nucleus
A positive ion has more protons than electrons.
A negative ion has more electrons than protons.
A neutral atom has an equal number of protons and electrons.
An isotope has the same number of protons of other isotopes of that element, but it
contains a different number of neutrons.
Isotope
U - 240
Atomic Mass
Look on
periodic table
Look on
periodic table
U - 238
Mass Number
240
Protons
92
Neutrons
148
Electrons
92
238
92
146
92
Helium has two naturally occurring isotopes, helium-3 and helium-4. The atomic mass
of helium is 4.003 amu. Which isotope is more abundant in nature? Helium-4
Radioactivity
Why does a radioactive isotope undergo radioactive decay? To become stable
Type of Radiation
Symbol
alpha
4
2He
beta
0
-1e
gamma
0
0Y
Penetration
ability
least
Mass
4 amu heaviest
0
most
0
How it affects the
nucleus
Atomic number
decreases by 2; Mass
number decreases by 4
Atomic number
increases by 1; Mass is
not affected.
Not affected
Describe nuclear fission: Splitting of a nucleus into fragments in order to increase
stability.
Describe nuclear fusion: The process of binding smaller nuclei into a single larger &
more stable nucleus. This is how elements heavier than helium are produced.
Define half-life: is the time required for one-half of a radioisotope’s nuclei to decay into
its products.
Periodicity
Fall 2008 Final Exam Review
On a periodic table be able to identify the location of the alkali metals, halogens, noble
gases, chalcogen, and alkaline earth metals.
Alkali metals – s1 – loses 1 electron – Group 1A
Alkaline earth metals – s2 – loses 2 electrons – Group 2A
Chalcogens – p4 – gains 2 electrons – Group 6A
Halogens – p5 – gains 1 electron – Group 7A
Noble Gases – p6 – doesn’t lose or gain electrons - STABLE
Know the number of valence electrons for each of the groups listed above.
Alkali metals – 1 valence electron
Alkaline earth metals – 2 valence electrons
Chalcogens – 6 valence electrons
Halogens – 7 valence electrons
Noble Gases – 8 valence electrons
Know the electron configuration for each element of the periodic table.
Know which elements are solids, liquids and gases.
List the liquids: Hg (metal) Br (nonmetal)
List the gases: H2, N2, O2, F2, Cl2, plus ALL of the noble gases
Know which elements are metals, nonmetals and metalloids. Be able to identify these on
a blank periodic table.
List the metalloids: B, Si, Ge, As, Sb, Te, Po, At
Metals form positive ions
Nonmetals form negative ions
Give 5 characteristics of a metal: malleable, ductile, good conductor of heat and
electricity, reacts with an acid, shiny (has luster)
Give 5 characteristics of a nonmetal: brittle, poor conductor of heat and electricity, does
NOT react with an acid, dull
Describe how electromagnetic radiation is emitted: (know all the steps)
1. A stable atom absorbs energy from an outside source.
2. The atom’s electrons jump to a higher energy level – (this causes the atom to
become unstable.)
3. In order for the atom to become stable again, the electrons return to the ground
state thus releasing the extra energy in the form of light.
Know the following periodic trends:
Trend
Atomic radius Ionic radius Electronegativity Ionization energy -
Across the period
Decrease
Decrease
Increase
Increase
Down a group
Increase
Increase
Decrease
Decrease
Fall 2008 Final Exam Review
What happens to the radius of an atom that becomes a positive ion? The atom gets
MUCH smaller. (radius decreases)
What happens to the radius of an atom that becomes a negative ion? The atom gets
MUCH bigger (radius increases)
Chemical Bonding
Describe the following bond types in terms of what happens to the electrons:
Ionic Bonds – A bond formed that involves a TRANSFER of electrons.
Covalent Bonds – A bond formed when two atoms SHARE electrons between
them.
Metallic Bonds – A bond formed between two metal ions whereby their electrons
are contributed to the “SEA of electrons”.
Bonding occurs to satisfy the _octet_ rule. Why? Once the atom has an electron
configuration of a noble gas, it becomes stable.
Write the formula for the following compounds:
Magnesium hydroxide Mg(OH)2
Aluminum nitride AlN______
Aluminum nitrate __Al(NO3)3__________
Aluminum nitrite ___ Al(NO2)3__________
Gold III phosphate ___AuPO4_________
Gold III phosphide ___AuP________
Gold III phosphite ___AuPO3________
Write the formula for the following compounds:
Chloric acid ___HClO3___________
Sulfuric acid ____H2SO4________________
Hydrosulfuric acid __H2S_______
Dinitrogen pentoxide _N2O5_____
Name the following:
H2CO3
SCl6
CuNO3
Ca3(PO4)2
_carbonic acid__
__sulfur hexachloride__
__copper (I) nitrate___
__calcium phosphate___
Give the name for single bonded hydrocarbons __alkanes__
Give the name for hydrocarbons containing a double bond __alkenes_____
Give the name for hydrocarbons containing a triple bond __alkynes___________
What makes a molecule polar? Due to unevenly shared covalent ponds, one side of a
molecule is negative while the other side is positive.
Give 2 examples of a polar molecule _water_ ___ammonia____
Fall 2008 Final Exam Review
What is meant by “like” dissolves in “like” – polar substances will dissolve in only polar
substances. For example, NaCl is polar (sodium is positive and chlorine is negative) so it
will dissolve in water, since water is polar.
Equations:
Relate the Law of Conservation of Mass to a balanced equation. The number and types
of atoms must be the same on both sides of the yield sign
How would you classify the following equations?
_2_MgO  _2_ Mg + _1_O2
_2_Na + _1_H2O  _2_NaOH + _1_H2
_____decomposition_______
_____single replacement______
1 NaOH + _1_HCl  _1_NaCl + _1_H2O _____double replacement_____
_2_ Mg + __O2 
__ C3H8
_2__ MgO
+ _5_O2 
Balance the above equations
_3__ CO2
________synthesis & combustion_
+ _4_H2O ____combustion______