CEM 141 END OF COURSE 2025/2026 QUESTIONS AND
ANSWERS RATED A+
✔✔What is the evidence from Thomson's experiment that all atoms contain electrons? -
✔✔The particles are identical regardless of the identity of the cathode(where they were
emitted from).
✔✔What is an alpha particle? - ✔✔Has 2 protons and 2 neutrons. It is the nucleus of a
Helium atom.
✔✔Coulomb's Law - ✔✔Negative and positive charges attract and like charges repel.
✔✔4 Types of Forces - ✔✔Gravitational, Electromagnetic, Strong Nuclear, Weak
Nuclear
✔✔Gravitational Force - ✔✔Responsible for attraction between objects that have mass.
✔✔Electromagnetic Force - ✔✔Responsible for attraction/repulsion for objects that
have an electric charge.
✔✔Kinetic Energy - ✔✔The energy associated with motion.
✔✔Potential Energy - ✔✔The energy associated with the position of a system of objects
in a field.
✔✔London Dispersion Forces - ✔✔
✔✔How many molecules must be present for LDF's to exist? - ✔✔Two or more
✔✔As the helium atoms approach what happens to the total energy? - ✔✔Stays the
same
✔✔As the helium atoms approach what happens to the kinetic energy? - ✔✔Increases
✔✔As the helium atoms approach what happens to the potential energy? -
✔✔Decreases
✔✔What happens to the total energy when the atoms get close to overlapping electron
clouds? - ✔✔Stays the same
✔✔What happens to the kinetic energy when the atoms get close to overlapping the
electron clouds? - ✔✔Decreases
ANSWERS RATED A+
✔✔What is the evidence from Thomson's experiment that all atoms contain electrons? -
✔✔The particles are identical regardless of the identity of the cathode(where they were
emitted from).
✔✔What is an alpha particle? - ✔✔Has 2 protons and 2 neutrons. It is the nucleus of a
Helium atom.
✔✔Coulomb's Law - ✔✔Negative and positive charges attract and like charges repel.
✔✔4 Types of Forces - ✔✔Gravitational, Electromagnetic, Strong Nuclear, Weak
Nuclear
✔✔Gravitational Force - ✔✔Responsible for attraction between objects that have mass.
✔✔Electromagnetic Force - ✔✔Responsible for attraction/repulsion for objects that
have an electric charge.
✔✔Kinetic Energy - ✔✔The energy associated with motion.
✔✔Potential Energy - ✔✔The energy associated with the position of a system of objects
in a field.
✔✔London Dispersion Forces - ✔✔
✔✔How many molecules must be present for LDF's to exist? - ✔✔Two or more
✔✔As the helium atoms approach what happens to the total energy? - ✔✔Stays the
same
✔✔As the helium atoms approach what happens to the kinetic energy? - ✔✔Increases
✔✔As the helium atoms approach what happens to the potential energy? -
✔✔Decreases
✔✔What happens to the total energy when the atoms get close to overlapping electron
clouds? - ✔✔Stays the same
✔✔What happens to the kinetic energy when the atoms get close to overlapping the
electron clouds? - ✔✔Decreases
