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Michigan State University
CEM 141 CEM141 exam 1 Questions and
Answers 2026 Latest Update
Atomic hypothesis (Feynman) Ans: All things are made of atoms in
perpetual motion; they attract at moderate distances and repel when
squeezed together.
Atom Ans: Smallest particle that retains the identity and properties of an
element; mostly empty space with a dense nucleus and surrounding
electrons.
Element Ans: Pure substance defined by a unique number of protons in its
atoms' nuclei.
Molecule Ans: Two or more atoms bonded together acting as a unit.
Subatomic particle Ans: Proton (+1, ~1 amu), neutron (0, ~1 amu), electron (-
1, ~1/2000 amu).
Quarks and gluons Ans: Constituents of protons and neutrons; held
together by the strong nuclear force.
Electrical neutrality of atoms Ans: In a neutral atom, #protons = #electrons,
so net charge is zero.
Nucleus Ans: Tiny, dense, positively charged center of the atom containing
protons and neutrons.
Electron cloud Ans: Region of space where electrons are found; accounts for
most atomic volume.
Heisenberg uncertainty principle Ans: At atomic scales, measuring a particle
perturbs it; position and momentum cannot both be known exactly.
Wave-particle duality Ans: Electrons, photons, and other quantum entities
show both wave-like and particle-like behavior.
© 2026 All rights reserved
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Forces in nature (overview) Ans: Gravity, electromagnetism, strong nuclear,
weak nuclear.
Gravity (chemistry context) Ans: Weakest force; negligible for
atomic/molecular interactions.
Electromagnetic force Ans: Attraction/repulsion between charges; dominant
force in chemical behavior.
Strong nuclear force Ans: Very strong, very short-range force that binds
protons and neutrons in the nucleus.
Weak nuclear force Ans: Very short-range force involved in certain
radioactive decays.
Scale of a gold atom Ans: Diameter < 1 nanometer (10⁻⁹ m); nucleus radius
~1.5 × 10⁻¹⁴ m.
Seeing atoms (indirect) Ans: Electron and force-probe microscopes (e.g.,
STM/AFM) provide images/computer reconstructions; not visible with light
microscopes.
Scientific theory Ans: Well-tested explanatory framework that integrates
evidence, makes predictions, and is revised with new data.
Falsifiability Ans: A scientific idea must be testable in ways that could show
it to be false.
Reproducibility Ans: Independent repetition of observations/experiments is
required for acceptance.
Natural vs. supernatural explanations Ans: Science works with observable,
measurable natural phenomena; supernatural claims are outside scientific
testing.
Greek atomism (Democritus/Leucippus) Ans: Proposed indivisible "atomos"
moving in a void; different shapes → different properties (insightful but
untested).
Four ancient "elements" Ans: Earth, air, fire, water (plus aether in some
traditions); superseded by modern elements.
© 2026 All rights reserved
Michigan State University
CEM 141 CEM141 exam 1 Questions and
Answers 2026 Latest Update
Atomic hypothesis (Feynman) Ans: All things are made of atoms in
perpetual motion; they attract at moderate distances and repel when
squeezed together.
Atom Ans: Smallest particle that retains the identity and properties of an
element; mostly empty space with a dense nucleus and surrounding
electrons.
Element Ans: Pure substance defined by a unique number of protons in its
atoms' nuclei.
Molecule Ans: Two or more atoms bonded together acting as a unit.
Subatomic particle Ans: Proton (+1, ~1 amu), neutron (0, ~1 amu), electron (-
1, ~1/2000 amu).
Quarks and gluons Ans: Constituents of protons and neutrons; held
together by the strong nuclear force.
Electrical neutrality of atoms Ans: In a neutral atom, #protons = #electrons,
so net charge is zero.
Nucleus Ans: Tiny, dense, positively charged center of the atom containing
protons and neutrons.
Electron cloud Ans: Region of space where electrons are found; accounts for
most atomic volume.
Heisenberg uncertainty principle Ans: At atomic scales, measuring a particle
perturbs it; position and momentum cannot both be known exactly.
Wave-particle duality Ans: Electrons, photons, and other quantum entities
show both wave-like and particle-like behavior.
© 2026 All rights reserved
, 2 | Page
Forces in nature (overview) Ans: Gravity, electromagnetism, strong nuclear,
weak nuclear.
Gravity (chemistry context) Ans: Weakest force; negligible for
atomic/molecular interactions.
Electromagnetic force Ans: Attraction/repulsion between charges; dominant
force in chemical behavior.
Strong nuclear force Ans: Very strong, very short-range force that binds
protons and neutrons in the nucleus.
Weak nuclear force Ans: Very short-range force involved in certain
radioactive decays.
Scale of a gold atom Ans: Diameter < 1 nanometer (10⁻⁹ m); nucleus radius
~1.5 × 10⁻¹⁴ m.
Seeing atoms (indirect) Ans: Electron and force-probe microscopes (e.g.,
STM/AFM) provide images/computer reconstructions; not visible with light
microscopes.
Scientific theory Ans: Well-tested explanatory framework that integrates
evidence, makes predictions, and is revised with new data.
Falsifiability Ans: A scientific idea must be testable in ways that could show
it to be false.
Reproducibility Ans: Independent repetition of observations/experiments is
required for acceptance.
Natural vs. supernatural explanations Ans: Science works with observable,
measurable natural phenomena; supernatural claims are outside scientific
testing.
Greek atomism (Democritus/Leucippus) Ans: Proposed indivisible "atomos"
moving in a void; different shapes → different properties (insightful but
untested).
Four ancient "elements" Ans: Earth, air, fire, water (plus aether in some
traditions); superseded by modern elements.
© 2026 All rights reserved
