CEM 141 EXAM 2 2026 INTRODUCTORY
CHEMISTRY ASSESSMENT QUESTIONS
SOLUTIONS GRADED A+
◉ ____ are the smallest distinguishable part of an element.
Answer: Atoms
◉ ________lower the potential energy of a system, and _________ tend to
raise the potential energy.
Answer: attractions and repulsions
◉ ________ change over time according to the evidence available.
Answer: theories
◉ All atoms/molecules attract each other because of the attractive
_________________ between them.
Answer: electromagnetic forces
◉ _________ form where the attractive forces and the repulsive forces
are equal.
Answer: stable systems
,◉ ____________of a phase change depends on the strength of the
intermolecular forces.
Answer: the temperature
◉ While constructing a scientific explanation you need 3 things?
Answer: claim, evidence and reasoning
◉ a ____ describes the phenomenon
Answer: law
◉ a ______ explains the phenomenon
Answer: theory
◉ the # of ______ distinguishes one element for another
Answer: protons
◉ _____ is the smallest unit of an element
Answer: atom
◉ Why was daltons atomic theory wrong?
,Answer: Because elements are not composed of small indivisible
indestructible particles called atoms. All atoms of an element are not
identical.
◉ ______ its a different type of elements but with a different number
of neutrons.
Answer: Isomers
◉ Which subatomic particle was discovered first?
Answer: electrons
◉ Why was the electron the first subatomic particle discovered?
Answer: because it is a charged particle on the outer layers of the
atom
◉ Who discovered the electron?
Answer: Thompson
◉ How did Thompson discover the electron?
Answer: The cathode ray tube experiment. Electrons are shot
through the metal and when they introduced the metal plate
(positive and negative). The ray was attracted towards the positively
charged plates, therefore, there has to be something negatively
charged within the ray.
, ◉ Thompsons experiment showed that the particles being shot
carried an ____________
Answer: electrical charge
◉ Thompsons experiment also showed that the type of ____ had no
affect on the behavior of the ray
Answer: metal
◉ Thompsons _____________ atom model showed that atoms contain
electrons embedded in the positvely charged atom.
Answer: plum pudding model
◉ Core principle of the atomic theory is that the idea that _____ is
composed of ______
Answer: matter is composed of atoms
◉ Root of atomic theories is from?
Answer: the greeks
◉ What did Ernest Rutherford's gold foil experiment show?
Answer: They shot alpha particles at gold foil and the particles went
through but every once and a while a particle was shot back.
CHEMISTRY ASSESSMENT QUESTIONS
SOLUTIONS GRADED A+
◉ ____ are the smallest distinguishable part of an element.
Answer: Atoms
◉ ________lower the potential energy of a system, and _________ tend to
raise the potential energy.
Answer: attractions and repulsions
◉ ________ change over time according to the evidence available.
Answer: theories
◉ All atoms/molecules attract each other because of the attractive
_________________ between them.
Answer: electromagnetic forces
◉ _________ form where the attractive forces and the repulsive forces
are equal.
Answer: stable systems
,◉ ____________of a phase change depends on the strength of the
intermolecular forces.
Answer: the temperature
◉ While constructing a scientific explanation you need 3 things?
Answer: claim, evidence and reasoning
◉ a ____ describes the phenomenon
Answer: law
◉ a ______ explains the phenomenon
Answer: theory
◉ the # of ______ distinguishes one element for another
Answer: protons
◉ _____ is the smallest unit of an element
Answer: atom
◉ Why was daltons atomic theory wrong?
,Answer: Because elements are not composed of small indivisible
indestructible particles called atoms. All atoms of an element are not
identical.
◉ ______ its a different type of elements but with a different number
of neutrons.
Answer: Isomers
◉ Which subatomic particle was discovered first?
Answer: electrons
◉ Why was the electron the first subatomic particle discovered?
Answer: because it is a charged particle on the outer layers of the
atom
◉ Who discovered the electron?
Answer: Thompson
◉ How did Thompson discover the electron?
Answer: The cathode ray tube experiment. Electrons are shot
through the metal and when they introduced the metal plate
(positive and negative). The ray was attracted towards the positively
charged plates, therefore, there has to be something negatively
charged within the ray.
, ◉ Thompsons experiment showed that the particles being shot
carried an ____________
Answer: electrical charge
◉ Thompsons experiment also showed that the type of ____ had no
affect on the behavior of the ray
Answer: metal
◉ Thompsons _____________ atom model showed that atoms contain
electrons embedded in the positvely charged atom.
Answer: plum pudding model
◉ Core principle of the atomic theory is that the idea that _____ is
composed of ______
Answer: matter is composed of atoms
◉ Root of atomic theories is from?
Answer: the greeks
◉ What did Ernest Rutherford's gold foil experiment show?
Answer: They shot alpha particles at gold foil and the particles went
through but every once and a while a particle was shot back.
