MSU CEM 141 EXAM QUESTIONS AND
ANSWERS
The statement "If I add cold milk to hot coffee the temperature will
decrease," is a? - -Claim, always include an explanation and reasoning to the
claim.
- Scientific Model - -Models are used to make testable predictions
- How much is a picometer? - -0.1 x 10^-12 meters
- Atomic Force Microscopy/ Scanning Tunneling Microscopy - -Microscopes
that now allows us to view atoms.
- Leaves are green in the summer because? - -A plant's leaves are green in
the summer because they contain chlorophyll. Chlorophyll is a natural
pigment that absorbs all wavelengths in the visible spectrum except green.
- How many naturally occurring elements exist? - -91
- What was Dalton's Atomic theory? (1808) - -- Elements are composed of
small particles called Atoms.
- Atoms of a given element are different from atoms of other elements.
-Chemical reactions happen when atoms are rearranged.
- Compounds contain 2 or more elements.
- What was J.J. Thomson's experiment, and what did he discover? - -Using a
Cathode Ray Tube, he noticed that particles emerged to the cathode disk,
and moved to another, the anode. These particles could be deflected by
electrical fields that would indicate that they would be negatively charged.
They were also deflected by magnetic fields, which showed the particles
carried the charge as the ray was bent. The most important observation was
that the type of cathode used did not matter, as these particles were still
emitted. Therefore, Thomson deduced that the particles were universal and
were in fact negatively charged components of the atom. (The Electron)
- - -
- What was Ernest Rutherford's experiment, what did he discover? - -Ernest
Rutherford fired Alpha particles (Hydrogen atoms) at a thin sheet of gold foil.
Had Thomson's theory been right about the plum pudding model, then the
atoms should have all passed right through the sheet with no exceptions.
However, a small ratio of these particles were deflected. With this
,information, Rutherford figured there was a small dense nucleus in the atom
and that most of the atom was empty space.
- What is the difference between Law and Theory? - -A law describes - tells
you what happens
A theory explains - tells you why it happens
- How big is an atom (H)? - -About 0.1 nanometer (0.1 x 10-9m)
- Which is biggest? Atom, Molecule, Cell, or it depends? - -
- Where did the idea of atoms come from? - -The Greeks
- Atoms - -The smallest unit of an element
- 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
- What happens to the potential energy when the atoms overlap electron
clouds? - -Increases
- Are gravitational forces meditated by fields? - -True
- Do gravitational forces require 2 or more objects? - -True
- Are gravitational forces always attractive? - -True
- Do gravitational forces increase as distance between the objects increase?
- -False
- Do gravitational forces increase as the mass of the object increases? - -
True
- Are electrostatic forces meditated by fields? - -True
- Do electrostatic forces require 2 or more objects? - -True
- Can electrostatic forces be either attractive or repulsive? - -True
- Do electrostatic forces decrease as distance between the objects increase?
- -True
- When a single chemical bond is breaking what happens to the energy? - -
The energy is absorbed
- Why do atoms move apart? - -The electron cloud moves them apart
- As the atoms get closer, which force is the strongest? - -Electrostatic
- At the potential minimum, which force is the strongest? - -ES Attraction
and ES repulsion are balanced
ANSWERS
The statement "If I add cold milk to hot coffee the temperature will
decrease," is a? - -Claim, always include an explanation and reasoning to the
claim.
- Scientific Model - -Models are used to make testable predictions
- How much is a picometer? - -0.1 x 10^-12 meters
- Atomic Force Microscopy/ Scanning Tunneling Microscopy - -Microscopes
that now allows us to view atoms.
- Leaves are green in the summer because? - -A plant's leaves are green in
the summer because they contain chlorophyll. Chlorophyll is a natural
pigment that absorbs all wavelengths in the visible spectrum except green.
- How many naturally occurring elements exist? - -91
- What was Dalton's Atomic theory? (1808) - -- Elements are composed of
small particles called Atoms.
- Atoms of a given element are different from atoms of other elements.
-Chemical reactions happen when atoms are rearranged.
- Compounds contain 2 or more elements.
- What was J.J. Thomson's experiment, and what did he discover? - -Using a
Cathode Ray Tube, he noticed that particles emerged to the cathode disk,
and moved to another, the anode. These particles could be deflected by
electrical fields that would indicate that they would be negatively charged.
They were also deflected by magnetic fields, which showed the particles
carried the charge as the ray was bent. The most important observation was
that the type of cathode used did not matter, as these particles were still
emitted. Therefore, Thomson deduced that the particles were universal and
were in fact negatively charged components of the atom. (The Electron)
- - -
- What was Ernest Rutherford's experiment, what did he discover? - -Ernest
Rutherford fired Alpha particles (Hydrogen atoms) at a thin sheet of gold foil.
Had Thomson's theory been right about the plum pudding model, then the
atoms should have all passed right through the sheet with no exceptions.
However, a small ratio of these particles were deflected. With this
,information, Rutherford figured there was a small dense nucleus in the atom
and that most of the atom was empty space.
- What is the difference between Law and Theory? - -A law describes - tells
you what happens
A theory explains - tells you why it happens
- How big is an atom (H)? - -About 0.1 nanometer (0.1 x 10-9m)
- Which is biggest? Atom, Molecule, Cell, or it depends? - -
- Where did the idea of atoms come from? - -The Greeks
- Atoms - -The smallest unit of an element
- 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
- What happens to the potential energy when the atoms overlap electron
clouds? - -Increases
- Are gravitational forces meditated by fields? - -True
- Do gravitational forces require 2 or more objects? - -True
- Are gravitational forces always attractive? - -True
- Do gravitational forces increase as distance between the objects increase?
- -False
- Do gravitational forces increase as the mass of the object increases? - -
True
- Are electrostatic forces meditated by fields? - -True
- Do electrostatic forces require 2 or more objects? - -True
- Can electrostatic forces be either attractive or repulsive? - -True
- Do electrostatic forces decrease as distance between the objects increase?
- -True
- When a single chemical bond is breaking what happens to the energy? - -
The energy is absorbed
- Why do atoms move apart? - -The electron cloud moves them apart
- As the atoms get closer, which force is the strongest? - -Electrostatic
- At the potential minimum, which force is the strongest? - -ES Attraction
and ES repulsion are balanced
