CEM 141 EVALUATION EXAM 2025/2026 QUESTIONS
AND ANSWERS RATED A+
✔✔Radioactivity - ✔✔The emission of elementary particles by some atoms when their
unstable nuclei disintegrate (see half-life). Materials composed of such atoms are
radioactive. (See alpha radiation, beta radiation, and gamma radiation.)
✔✔Nucleus - ✔✔nucleus is the positively charged center of the atom consisting of
protons and neutrons.
✔✔Proton - ✔✔A positively charged particle within a nucleus ... The number of protons
in an element's nucleus is called the atomic number.
✔✔Neutron - ✔✔Neutral partials witching a nucleus. They contain no electrical charge
subatomic particle found in the nucleus of atoms that differs from the other subatomic
particles (called "protons") in the nucleus of atoms because neutrons have no (zero)
charge whereas each proton has a positive charge of +1.
✔✔Atomic Mass Unit - ✔✔AMU - 1/12 of the mass of a carbon -12 atom
it is a unit of mass used to express atomic masses and molecular masses.
✔✔Atomic Number - ✔✔The number of protons in a atom's nucleus and is given the
symbol Z
✔✔Chemical Symbol - ✔✔an abbreviation of a chemical element, symbols in a periodic
table
✔✔Isotope - ✔✔An atom that has the same number of protons but different number of
neutrons
✔✔What is a mass number and the symbol represents it? - ✔✔It is the sum of neutrons
and protons in an atom and is represented by the symbol A. It also can me written as X-
A. Ex: Ne-20
✔✔Natural Abundance - ✔✔abundance of isotopes of a chemical element as naturally
found on a planet
when a natural element has a roughly constant percentage of isotopes
✔✔Ion - ✔✔an atom that has obtained a charge - either + or -.
✔✔Anion - ✔✔- a negatively charged ion
✔✔Cation - ✔✔- a positively charged ion
,✔✔Periodic Table - ✔✔All elements are defined by a 1 or 2 letter symbol. The atomic
number listed on top tells us the number of protons and vice-versa
✔✔accuracy - ✔✔the measure of how close a measurement is to the actual, exact
value
✔✔Precision - ✔✔the relative proximity of a set of measurements to each other or how
reproducible they are. For an individual measurement - how many places to the right of
the decimal are reported.
✔✔Random error - ✔✔Random error is always present in a measurement. It is caused
by inherently unpredictable fluctuations in the readings of a measurement apparatus or
in the experimenter's interpretation of the instrumental reading.
✔✔Systematic Error - ✔✔. A systematic error (an estimate of which is known as a
measurement bias) is associated with the fact that a measured value contains an offset.
This type of error affects all of the data by shifting it either too high or low. This is an
error that is built into the apparatus and can not be reduced by repeat readings. To
remove the size of the error is found and then minused from all of the results.
✔✔Density - ✔✔mass per unit volume of a substance
Relationship between mass and volume D=Mass/Volume
✔✔Intensive Properties of Matter - ✔✔a property that depends on the type of matter in
a sample, not the amount of matter. (Intensive Properties can be helpful clues to
identifying unknown substances.
a property that depends on the type of matter in a sample, not the amount of matter.
(Intensive Properties can be helpful clues to identifying unknown substances.
✔✔Extensive Properties of Matter - ✔✔property that depends on the amount of matter
in a sample
Extensive properties, such as mass and volume, depend on the amount of matter that
is being measured.
✔✔Energy - ✔✔The ability to do work or produce heat.
✔✔Kinetic Energy - ✔✔Energy due to the motion of the object.
✔✔Potential Energy - ✔✔Energy due to position or composition.
✔✔Thermal Energy - ✔✔Thermal energy is the internal energy of an object due to the
kinetic energy of its atoms and/or molecules. The atoms and/or molecules of a hotter
object have greater kinetic energy than those of a colder one, in the form of vibrational,
rotational, or, in the case of a gas, translational motion.
, ✔✔Law of Conservation of Energy - ✔✔Energy can be converted from one form to
another but can neither be created nor destroyed.
and total energy remains constant
✔✔Mole - ✔✔The amount of a substance that contains 6.02 x 10^23 representative
particles of that substance
The unit of a mole gives us a way of counting a large number of items with smaller
numbers
✔✔Avogadro's number - ✔✔-the number of representative particles contained in one
mole of a substance; equal to 6.02 x 10^23 particles.
- Avogadro's number is a proportion that relates molar mass on an atomic scale to
physical mass on a human scale. Avogadro's number is defined as the number of
elementary particles (molecules, atoms, compounds, etc.) per mole of a substance. It is
equal to 6.022×1023 mol-1 and is expressed as the symbol NA.
✔✔amplitude - ✔✔related to the vertical height of the crest and determines the intensity
of the light
✔✔wavelength - ✔✔is the physical distance between crests of the light wave
✔✔frequency - ✔✔the number of crests that pass a point in a given time
✔✔speed of light - ✔✔3.00×108 m/s
✔✔Interaction with the EM Spectrum - ✔✔The light that we see with our eyes makes up
the small portion of the EM spectrum called visible light The EM spectrum contains
many types of light ranging from radio waves to gamma radiation.
Radio waves, Microwaves, infrared, visible ultraviolet, x-rays, gamma
✔✔interference - ✔✔Interactions between waves ( Note: there are two types of
interference: Constructive and Destructive).
✔✔diffraction - ✔✔The bending of waves around a barrier or through an opening.
✔✔atomic spectroscopy - ✔✔When atoms absorb energy, they often re-emit that
energy in the form of light - atomic spectra
Even though we may see a single color of light, there are usually several wavelengths
being emittedwe can separate those wavelengths through a refractive device like a
prism
✔✔Emission Spectrum - ✔✔Each element has a characteristic pattern of wavelengths
AND ANSWERS RATED A+
✔✔Radioactivity - ✔✔The emission of elementary particles by some atoms when their
unstable nuclei disintegrate (see half-life). Materials composed of such atoms are
radioactive. (See alpha radiation, beta radiation, and gamma radiation.)
✔✔Nucleus - ✔✔nucleus is the positively charged center of the atom consisting of
protons and neutrons.
✔✔Proton - ✔✔A positively charged particle within a nucleus ... The number of protons
in an element's nucleus is called the atomic number.
✔✔Neutron - ✔✔Neutral partials witching a nucleus. They contain no electrical charge
subatomic particle found in the nucleus of atoms that differs from the other subatomic
particles (called "protons") in the nucleus of atoms because neutrons have no (zero)
charge whereas each proton has a positive charge of +1.
✔✔Atomic Mass Unit - ✔✔AMU - 1/12 of the mass of a carbon -12 atom
it is a unit of mass used to express atomic masses and molecular masses.
✔✔Atomic Number - ✔✔The number of protons in a atom's nucleus and is given the
symbol Z
✔✔Chemical Symbol - ✔✔an abbreviation of a chemical element, symbols in a periodic
table
✔✔Isotope - ✔✔An atom that has the same number of protons but different number of
neutrons
✔✔What is a mass number and the symbol represents it? - ✔✔It is the sum of neutrons
and protons in an atom and is represented by the symbol A. It also can me written as X-
A. Ex: Ne-20
✔✔Natural Abundance - ✔✔abundance of isotopes of a chemical element as naturally
found on a planet
when a natural element has a roughly constant percentage of isotopes
✔✔Ion - ✔✔an atom that has obtained a charge - either + or -.
✔✔Anion - ✔✔- a negatively charged ion
✔✔Cation - ✔✔- a positively charged ion
,✔✔Periodic Table - ✔✔All elements are defined by a 1 or 2 letter symbol. The atomic
number listed on top tells us the number of protons and vice-versa
✔✔accuracy - ✔✔the measure of how close a measurement is to the actual, exact
value
✔✔Precision - ✔✔the relative proximity of a set of measurements to each other or how
reproducible they are. For an individual measurement - how many places to the right of
the decimal are reported.
✔✔Random error - ✔✔Random error is always present in a measurement. It is caused
by inherently unpredictable fluctuations in the readings of a measurement apparatus or
in the experimenter's interpretation of the instrumental reading.
✔✔Systematic Error - ✔✔. A systematic error (an estimate of which is known as a
measurement bias) is associated with the fact that a measured value contains an offset.
This type of error affects all of the data by shifting it either too high or low. This is an
error that is built into the apparatus and can not be reduced by repeat readings. To
remove the size of the error is found and then minused from all of the results.
✔✔Density - ✔✔mass per unit volume of a substance
Relationship between mass and volume D=Mass/Volume
✔✔Intensive Properties of Matter - ✔✔a property that depends on the type of matter in
a sample, not the amount of matter. (Intensive Properties can be helpful clues to
identifying unknown substances.
a property that depends on the type of matter in a sample, not the amount of matter.
(Intensive Properties can be helpful clues to identifying unknown substances.
✔✔Extensive Properties of Matter - ✔✔property that depends on the amount of matter
in a sample
Extensive properties, such as mass and volume, depend on the amount of matter that
is being measured.
✔✔Energy - ✔✔The ability to do work or produce heat.
✔✔Kinetic Energy - ✔✔Energy due to the motion of the object.
✔✔Potential Energy - ✔✔Energy due to position or composition.
✔✔Thermal Energy - ✔✔Thermal energy is the internal energy of an object due to the
kinetic energy of its atoms and/or molecules. The atoms and/or molecules of a hotter
object have greater kinetic energy than those of a colder one, in the form of vibrational,
rotational, or, in the case of a gas, translational motion.
, ✔✔Law of Conservation of Energy - ✔✔Energy can be converted from one form to
another but can neither be created nor destroyed.
and total energy remains constant
✔✔Mole - ✔✔The amount of a substance that contains 6.02 x 10^23 representative
particles of that substance
The unit of a mole gives us a way of counting a large number of items with smaller
numbers
✔✔Avogadro's number - ✔✔-the number of representative particles contained in one
mole of a substance; equal to 6.02 x 10^23 particles.
- Avogadro's number is a proportion that relates molar mass on an atomic scale to
physical mass on a human scale. Avogadro's number is defined as the number of
elementary particles (molecules, atoms, compounds, etc.) per mole of a substance. It is
equal to 6.022×1023 mol-1 and is expressed as the symbol NA.
✔✔amplitude - ✔✔related to the vertical height of the crest and determines the intensity
of the light
✔✔wavelength - ✔✔is the physical distance between crests of the light wave
✔✔frequency - ✔✔the number of crests that pass a point in a given time
✔✔speed of light - ✔✔3.00×108 m/s
✔✔Interaction with the EM Spectrum - ✔✔The light that we see with our eyes makes up
the small portion of the EM spectrum called visible light The EM spectrum contains
many types of light ranging from radio waves to gamma radiation.
Radio waves, Microwaves, infrared, visible ultraviolet, x-rays, gamma
✔✔interference - ✔✔Interactions between waves ( Note: there are two types of
interference: Constructive and Destructive).
✔✔diffraction - ✔✔The bending of waves around a barrier or through an opening.
✔✔atomic spectroscopy - ✔✔When atoms absorb energy, they often re-emit that
energy in the form of light - atomic spectra
Even though we may see a single color of light, there are usually several wavelengths
being emittedwe can separate those wavelengths through a refractive device like a
prism
✔✔Emission Spectrum - ✔✔Each element has a characteristic pattern of wavelengths
