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Michigan State University
CEM 141 CEM 141 Exam 1 Review
Questions and Answers 2026 Latest Update
Constructing a Scientific Explanation Ans: 1. Claim (target of explanation)
2. Evidence (data used to support)
3. Reasoning (connection between claim and evidence)
Scientific Theory Ans: explains how/why; best available explanation of
existing evidence; makes testable predictions; is falsifiable; may change over
time with new evidence
Difference Between Law and Theory Ans: Law: phenomenon; explains WHAT
Theory: tells WHY
How do we know atoms exist? Ans: We can see them using atomic force
microscopy (AFM) and scanning tunneling microscopy (STM)
Atomic Theory Development Ans: The original idea came from the Greeks;
wasn't a scientific theory but philosophy (Ex. Elements=earth, fire, air, water
and were thought to be in constant motion based on watching the
movement of specks of dust in sunlight and that there was nothing between
them AKA Brownian Motion)
What distinguishes one element from another? How do atoms of different
elements differ? Ans: Different # of protons and atomic symbol
What types of evidence might be used to conclude tat you had isolated a
new element? Ans: Would have new properties
What types of elements would be difficult to identify? Ans: Ones that aren't
reactive (Ex. Noble gases)
© 2026 All rights reserved
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What is the difference between an atom and a molecule? Ans: Molecule:
collection of atoms chemically bonded
What is the difference between an element and a compound? Ans: An
element is one type of atom vs a compound is several different atoms
connected
Atom Ans: is the smallest unit of an element
Dalton's Atomic Theory Ans: 1. Elements are composed of small indivisible,
indestructible particles called atoms (NOT TRUE)
2. All atoms of an element are identical and have the same mass and
properties (NOT TRUE)
3. Atoms of a given element are different from atoms of other elements.
(TRUE)
4. Compounds are formed by combinations of atoms of 2 or more elements
(TRUE)
5. Chemical reactions are due to the rearrangement of atoms, atoms (matter)
are neither created nor destroyed during a reaction (TRUE)
Atoms have a subatomic structure Ans: The electron was discovered first (it
was the easiest to move and detect) by JJ Thompson
Discovery of Electron Ans: Cathode ray tube: glass tube consisting of 2
electrodes under very low pressure. When a high voltage is applied, cathode
emits "particles" that move toward anode. Particle rays bend toward positive
plate. Therefore they're negatively charged particles.
Thompson's Atomic Model Ans: Plum Pudding Model
Thompson's Experiment showed... Ans: "particles" emerged from one disc
(the cathode) and moved to the other (the anode); these particles could be
deflected by electrical fields in a direction that would indicate they were
negatively charged; the particles could also be deflected by magnetic fields;
the particles carried the electrical charge—that is if the ray was bent, for
example by a magnetic field, the charge went with it; the metal that the
cathode was made of didn't affect the behavior of the ray—so whatever the
© 2026 All rights reserved
Michigan State University
CEM 141 CEM 141 Exam 1 Review
Questions and Answers 2026 Latest Update
Constructing a Scientific Explanation Ans: 1. Claim (target of explanation)
2. Evidence (data used to support)
3. Reasoning (connection between claim and evidence)
Scientific Theory Ans: explains how/why; best available explanation of
existing evidence; makes testable predictions; is falsifiable; may change over
time with new evidence
Difference Between Law and Theory Ans: Law: phenomenon; explains WHAT
Theory: tells WHY
How do we know atoms exist? Ans: We can see them using atomic force
microscopy (AFM) and scanning tunneling microscopy (STM)
Atomic Theory Development Ans: The original idea came from the Greeks;
wasn't a scientific theory but philosophy (Ex. Elements=earth, fire, air, water
and were thought to be in constant motion based on watching the
movement of specks of dust in sunlight and that there was nothing between
them AKA Brownian Motion)
What distinguishes one element from another? How do atoms of different
elements differ? Ans: Different # of protons and atomic symbol
What types of evidence might be used to conclude tat you had isolated a
new element? Ans: Would have new properties
What types of elements would be difficult to identify? Ans: Ones that aren't
reactive (Ex. Noble gases)
© 2026 All rights reserved
, 2 | Page
What is the difference between an atom and a molecule? Ans: Molecule:
collection of atoms chemically bonded
What is the difference between an element and a compound? Ans: An
element is one type of atom vs a compound is several different atoms
connected
Atom Ans: is the smallest unit of an element
Dalton's Atomic Theory Ans: 1. Elements are composed of small indivisible,
indestructible particles called atoms (NOT TRUE)
2. All atoms of an element are identical and have the same mass and
properties (NOT TRUE)
3. Atoms of a given element are different from atoms of other elements.
(TRUE)
4. Compounds are formed by combinations of atoms of 2 or more elements
(TRUE)
5. Chemical reactions are due to the rearrangement of atoms, atoms (matter)
are neither created nor destroyed during a reaction (TRUE)
Atoms have a subatomic structure Ans: The electron was discovered first (it
was the easiest to move and detect) by JJ Thompson
Discovery of Electron Ans: Cathode ray tube: glass tube consisting of 2
electrodes under very low pressure. When a high voltage is applied, cathode
emits "particles" that move toward anode. Particle rays bend toward positive
plate. Therefore they're negatively charged particles.
Thompson's Atomic Model Ans: Plum Pudding Model
Thompson's Experiment showed... Ans: "particles" emerged from one disc
(the cathode) and moved to the other (the anode); these particles could be
deflected by electrical fields in a direction that would indicate they were
negatively charged; the particles could also be deflected by magnetic fields;
the particles carried the electrical charge—that is if the ray was bent, for
example by a magnetic field, the charge went with it; the metal that the
cathode was made of didn't affect the behavior of the ray—so whatever the
© 2026 All rights reserved
