CEM 141 CORE EXAM SET 2025/2026 QUESTIONS AND
ANSWERS RATED A+
✔✔Atoms make up - ✔✔molecules
✔✔Molecules make up - ✔✔cells
✔✔Length of a cell - ✔✔.1 micrometer (10^-5)
✔✔Length of an atom - ✔✔.1 nanometer (10^-9)
✔✔Atomos - ✔✔-uncuttable
-established by greeks
-elements=earth, air, fire, water
✔✔Brownian motion - ✔✔Chaotic movement of colloidal particles
-macroscopic
✔✔Properties of atoms of different elements - ✔✔different due to protons
✔✔Dalton's Atomic Theory - ✔✔1) elements are composed of small indivisible,
indestructible particles: atoms-- FALSE because of ions
2)atoms of same element are identical-- FALSE because of isotopes.
3) atoms of a given element are different from atoms of another element
4) compounds form from combinations of atoms of 2+ elements
5) chemical reactions are due to the rearrangements of atoms (atoms aren't
created/destroyed)
✔✔Electrons were the first discovered subatomic particle because - ✔✔-they are on the
outside of the atom
-electrons have a charge so they were easy to detect
✔✔Thomson's Plum Pudding Model - ✔✔Electrons are spread throughout the atom, like
blueberries in a muffin
✔✔Gold foil experiment negates plum pudding model - ✔✔alpha particles should've
gone straight through the foil if the plum pudding model were true
✔✔Alpha particle - ✔✔A cluster of 2 protons and 2 neutrons emitted from a nucleus in
one type of radioactivity
,✔✔Gold foil experiment - ✔✔-rutherford
-shot alpha particles at a hammered down piece of gold and used a detector shield to
discover that most mass is contained in a small nucleus with a positive charge bc it
repelled the alpha particles
-most alpha particles went straight through the foil, but some deflected on
angles=discovery of nucleus
✔✔Rutherford's Planetary Model - ✔✔-Most of the atom is empty space
-he knew it was wrong bc of the way it is drawn, it would implode on itself
✔✔Columb's Law - ✔✔explains how atoms interact with an electrostatic force
✔✔Strong force - ✔✔short range interaction occurring between objects made of quarks
✔✔Weak force - ✔✔short range interaction between elementary particles
✔✔Mass and gravitational force have a - ✔✔-positive correlation
-more mass=stronger gravitational force
✔✔Distance and gravitational force have a - ✔✔-negative correlation
-more distance=weaker gravitational force
✔✔Any change in matter is accompanied by - ✔✔change in energy
✔✔Anytime a force changes what happens to potential energy - ✔✔it changes
✔✔As kinetic energy increases, potential energy - ✔✔decreases
✔✔Energy is only transferred - ✔✔between objects through collisions/contact OR
transformed between potential energy and kinetic energy
✔✔What makes atoms stick together - ✔✔charged particles
✔✔As atoms move closer which force is strongest - ✔✔electrostatic attraction
✔✔As the atoms move even closer, which force is the strongest - ✔✔electrostatic
repulsion
✔✔At the potential minimum, which force is the strongest - ✔✔electrostatic attraction
and repulsion are equal
✔✔Atoms don't stay in the potential minimum because - ✔✔the atoms have a lot of
energy, meaning they can break the LDFs and move apart again
, -to keep them in the potential minimum, you must decrease their energy by adding a 3rd
atom
✔✔Why do atoms oscillate (go back and forth) - ✔✔there are attractive and repulsive
forces in action
✔✔What happens when thermal energy is added to atoms - ✔✔kinetic energy is
transferred upon collision
-temp is directly related to average kinetic energy
✔✔Breaking a bond - ✔✔energy is absorbed
✔✔Forming a bond - ✔✔energy is released
✔✔Atoms are mostly composed of empty space. What model of the atom would be
evidence for this claim? - ✔✔Rutherford's planetary model
✔✔As two protons move toward each other, the potential energy of the system will -
✔✔increase because of the repulsive force between the like charges
✔✔Dalton's atomic theory - ✔✔1) elements are composed of atoms. 2) atoms of same
element are identical, but differ from other elements. 3) elements can mix together 4)
atoms only change when mixed with other elements
✔✔Thomson observed that the type of metal used for the cathode did not affect the
behavior of the cathode ray. what claim does this piece of evidence support? - ✔✔All
atoms contain electrons
✔✔How would the strength of the electrostatic force change if the distance between two
charged objects increased? - ✔✔The electrostatic force would become weaker
✔✔What is true for london dispersion forces and covalent bonds - ✔✔They are both
attractive interactions and they both release energy when they are formed
✔✔When oxygen boils - ✔✔london dispersion forces between the O2 molecules are
overcome
✔✔Thomsons cathode ray tube experiment showed the beam of emitted particles was
deflected by charged plates. he used this evidence to support his claim that -
✔✔electrons carried the electrical charge
✔✔Scientific theory - ✔✔explains the phenomenon
ANSWERS RATED A+
✔✔Atoms make up - ✔✔molecules
✔✔Molecules make up - ✔✔cells
✔✔Length of a cell - ✔✔.1 micrometer (10^-5)
✔✔Length of an atom - ✔✔.1 nanometer (10^-9)
✔✔Atomos - ✔✔-uncuttable
-established by greeks
-elements=earth, air, fire, water
✔✔Brownian motion - ✔✔Chaotic movement of colloidal particles
-macroscopic
✔✔Properties of atoms of different elements - ✔✔different due to protons
✔✔Dalton's Atomic Theory - ✔✔1) elements are composed of small indivisible,
indestructible particles: atoms-- FALSE because of ions
2)atoms of same element are identical-- FALSE because of isotopes.
3) atoms of a given element are different from atoms of another element
4) compounds form from combinations of atoms of 2+ elements
5) chemical reactions are due to the rearrangements of atoms (atoms aren't
created/destroyed)
✔✔Electrons were the first discovered subatomic particle because - ✔✔-they are on the
outside of the atom
-electrons have a charge so they were easy to detect
✔✔Thomson's Plum Pudding Model - ✔✔Electrons are spread throughout the atom, like
blueberries in a muffin
✔✔Gold foil experiment negates plum pudding model - ✔✔alpha particles should've
gone straight through the foil if the plum pudding model were true
✔✔Alpha particle - ✔✔A cluster of 2 protons and 2 neutrons emitted from a nucleus in
one type of radioactivity
,✔✔Gold foil experiment - ✔✔-rutherford
-shot alpha particles at a hammered down piece of gold and used a detector shield to
discover that most mass is contained in a small nucleus with a positive charge bc it
repelled the alpha particles
-most alpha particles went straight through the foil, but some deflected on
angles=discovery of nucleus
✔✔Rutherford's Planetary Model - ✔✔-Most of the atom is empty space
-he knew it was wrong bc of the way it is drawn, it would implode on itself
✔✔Columb's Law - ✔✔explains how atoms interact with an electrostatic force
✔✔Strong force - ✔✔short range interaction occurring between objects made of quarks
✔✔Weak force - ✔✔short range interaction between elementary particles
✔✔Mass and gravitational force have a - ✔✔-positive correlation
-more mass=stronger gravitational force
✔✔Distance and gravitational force have a - ✔✔-negative correlation
-more distance=weaker gravitational force
✔✔Any change in matter is accompanied by - ✔✔change in energy
✔✔Anytime a force changes what happens to potential energy - ✔✔it changes
✔✔As kinetic energy increases, potential energy - ✔✔decreases
✔✔Energy is only transferred - ✔✔between objects through collisions/contact OR
transformed between potential energy and kinetic energy
✔✔What makes atoms stick together - ✔✔charged particles
✔✔As atoms move closer which force is strongest - ✔✔electrostatic attraction
✔✔As the atoms move even closer, which force is the strongest - ✔✔electrostatic
repulsion
✔✔At the potential minimum, which force is the strongest - ✔✔electrostatic attraction
and repulsion are equal
✔✔Atoms don't stay in the potential minimum because - ✔✔the atoms have a lot of
energy, meaning they can break the LDFs and move apart again
, -to keep them in the potential minimum, you must decrease their energy by adding a 3rd
atom
✔✔Why do atoms oscillate (go back and forth) - ✔✔there are attractive and repulsive
forces in action
✔✔What happens when thermal energy is added to atoms - ✔✔kinetic energy is
transferred upon collision
-temp is directly related to average kinetic energy
✔✔Breaking a bond - ✔✔energy is absorbed
✔✔Forming a bond - ✔✔energy is released
✔✔Atoms are mostly composed of empty space. What model of the atom would be
evidence for this claim? - ✔✔Rutherford's planetary model
✔✔As two protons move toward each other, the potential energy of the system will -
✔✔increase because of the repulsive force between the like charges
✔✔Dalton's atomic theory - ✔✔1) elements are composed of atoms. 2) atoms of same
element are identical, but differ from other elements. 3) elements can mix together 4)
atoms only change when mixed with other elements
✔✔Thomson observed that the type of metal used for the cathode did not affect the
behavior of the cathode ray. what claim does this piece of evidence support? - ✔✔All
atoms contain electrons
✔✔How would the strength of the electrostatic force change if the distance between two
charged objects increased? - ✔✔The electrostatic force would become weaker
✔✔What is true for london dispersion forces and covalent bonds - ✔✔They are both
attractive interactions and they both release energy when they are formed
✔✔When oxygen boils - ✔✔london dispersion forces between the O2 molecules are
overcome
✔✔Thomsons cathode ray tube experiment showed the beam of emitted particles was
deflected by charged plates. he used this evidence to support his claim that -
✔✔electrons carried the electrical charge
✔✔Scientific theory - ✔✔explains the phenomenon
