SCH4U Unit 2 Exam Questions with Correct Answers Latest Update 2025-2026
something that uses familiar ideas to explain unfamiliar facts observed in nature is known as... -
Answers a model. it can be changed as new information is collected
T or F: the atomic model started out in 400 BC, having the appearance of a billiard ball - Answers
true
who was the greek philosopher that began the search for a description of matter? - Answers
Democritus; over 2400 years ago!
democritus named the smallest piece of matter ______, which meant ___ __ __ ___ - Answers
atomos, not to be cut
what is the name of the current theory we use for atoms? - Answers the modern wave model
which english chemist from the 1800s deduced that...
1. all elements are composed of atoms which are indivisible and indestructable
2. atoms of the same element are exactly alike
3. compounds are formed by the joining of two or more atoms - Answers dalton
who came up with the plum pudding model ( in 1897), and what did it imply about atoms? (3
points) - Answers J.J Thompson; implied that an atom is made of even smaller particles, and
WAS divisible
J.J Thompson discovered the electron through what? - Answers by passing an electric current
through a gas (which gave off rays of negatively charged particles)
rutherford's experiment involved shooting _____ particles at a thin sheet of ____ foil. - Answers
alpha, gold
in Rutherford's gold foil experiment, some of the alpha partices bounced back as opposed to
going through the gold sheet.
this meant that... (2 points) - Answers 1. atoms are mostly made of open space
2. the center of the atom was positively charged
Niels Bohr created the theory that.... - Answers electrons move in definite orbits around the
nucleus that were considered "energy levels"
, the locations of electrons depends on how much ______ the electron has. - Answers energy
what experiments/study did Max Planck start the quantum revolution from? - Answers the light
emitted by hot objects
why does an object turn from red to white as it gets hotter? (blackbody radiation) - Answers as
the objects gets hotter, the light emitted by the object must be accompanied by light of higher
wavelength (e.g blue)
How was the ultraviolet catastrophe solved? - Answers by assuming that energy was NOT
continuously divisible, but rather that it comes in discrete "packets" or quanta!
T or F: energy is continuous - Answers false: proven mathematically by Max Planck, the energy
of the oscillating atoms in heated solids with multiples of a small quantity of energy
what is known as a small discrete, indivisible quantity? what is this for light? - Answers quantum
(plural; quanta), photon
light is a wave composed of ... (2 points) - Answers electric and magnetic fields
the release of electrons from a substance due to light striking the surface of a metal is known
as... - Answers the photoelectric effect (an ammeter can record the electric current in the circuit)
T or F: A quantum of red light contains less energy than a quantum of UV light - Answers true
the classical theory regarding the electrons of an atom didn't make sense because... - Answers
the orbiting electron would emit photons of electromagnetic radiation constantly, which would
make it lose energy.
this would then make it spiral towards the nucleus and collapse the atom
T or F: Bohr said that if the light released or absorbed from an atom was quantized, then the
electron of the atom must also be quantized - Answers true
bohr's first postulate says that electrons do not radiate ______ as they orbit the nucleus.
each orbit corresponds to a state of constant energy, known as a __________ state - Answers
energy, stationary
when electrons "jump" from one orbit/energy level to another, it is called an electron __________
or quantum ____ - Answers electron transition, quantum jump
bohr's second postulate states that electrons can change their energy only by undergoing what?
- Answers a transition from one stationary state to another
something that uses familiar ideas to explain unfamiliar facts observed in nature is known as... -
Answers a model. it can be changed as new information is collected
T or F: the atomic model started out in 400 BC, having the appearance of a billiard ball - Answers
true
who was the greek philosopher that began the search for a description of matter? - Answers
Democritus; over 2400 years ago!
democritus named the smallest piece of matter ______, which meant ___ __ __ ___ - Answers
atomos, not to be cut
what is the name of the current theory we use for atoms? - Answers the modern wave model
which english chemist from the 1800s deduced that...
1. all elements are composed of atoms which are indivisible and indestructable
2. atoms of the same element are exactly alike
3. compounds are formed by the joining of two or more atoms - Answers dalton
who came up with the plum pudding model ( in 1897), and what did it imply about atoms? (3
points) - Answers J.J Thompson; implied that an atom is made of even smaller particles, and
WAS divisible
J.J Thompson discovered the electron through what? - Answers by passing an electric current
through a gas (which gave off rays of negatively charged particles)
rutherford's experiment involved shooting _____ particles at a thin sheet of ____ foil. - Answers
alpha, gold
in Rutherford's gold foil experiment, some of the alpha partices bounced back as opposed to
going through the gold sheet.
this meant that... (2 points) - Answers 1. atoms are mostly made of open space
2. the center of the atom was positively charged
Niels Bohr created the theory that.... - Answers electrons move in definite orbits around the
nucleus that were considered "energy levels"
, the locations of electrons depends on how much ______ the electron has. - Answers energy
what experiments/study did Max Planck start the quantum revolution from? - Answers the light
emitted by hot objects
why does an object turn from red to white as it gets hotter? (blackbody radiation) - Answers as
the objects gets hotter, the light emitted by the object must be accompanied by light of higher
wavelength (e.g blue)
How was the ultraviolet catastrophe solved? - Answers by assuming that energy was NOT
continuously divisible, but rather that it comes in discrete "packets" or quanta!
T or F: energy is continuous - Answers false: proven mathematically by Max Planck, the energy
of the oscillating atoms in heated solids with multiples of a small quantity of energy
what is known as a small discrete, indivisible quantity? what is this for light? - Answers quantum
(plural; quanta), photon
light is a wave composed of ... (2 points) - Answers electric and magnetic fields
the release of electrons from a substance due to light striking the surface of a metal is known
as... - Answers the photoelectric effect (an ammeter can record the electric current in the circuit)
T or F: A quantum of red light contains less energy than a quantum of UV light - Answers true
the classical theory regarding the electrons of an atom didn't make sense because... - Answers
the orbiting electron would emit photons of electromagnetic radiation constantly, which would
make it lose energy.
this would then make it spiral towards the nucleus and collapse the atom
T or F: Bohr said that if the light released or absorbed from an atom was quantized, then the
electron of the atom must also be quantized - Answers true
bohr's first postulate says that electrons do not radiate ______ as they orbit the nucleus.
each orbit corresponds to a state of constant energy, known as a __________ state - Answers
energy, stationary
when electrons "jump" from one orbit/energy level to another, it is called an electron __________
or quantum ____ - Answers electron transition, quantum jump
bohr's second postulate states that electrons can change their energy only by undergoing what?
- Answers a transition from one stationary state to another
