CEM 141 MSU Exam 2 Questions with Detailed
Verified Answers
Which reaction requires the most energy?
A. N(g) → N+(g) + e -
B. N+(g) → N2+(g) + e -
C. F(g) → F+(g) + e -
D. F+(g) → F2+(g) + e - Ans: D. F+(g) → F2+(g) + e -
Fluorine has a higher effective nuclear charge than Nitrogen - so it is harder to remove
an electron (takes more energy because the electron is more strongly attracted by the
nucleus). Effective nuclear charge is the same for F and F+ because the number of
protons and core electrons are not changed. However, when the number of electrons
is reduced, the repulsion between electrons decreases which results in a decrease in
the radius of the electron cloud because the point at which attractions and repulsions
are balanced is closer to the nucleus when there is less repulsion. When the radius of
the electron cloud decreases, the strength of the attraction between the nucleus and
the valence electrons increases which increases the amount of energy required to
remove an electron (ionization energy).
Which has a larger atomic radius? Mg or Ar and why. Ans: Mg, because its valence
electrons are not as strongly attracted towards the nucleus as those in Ar.
, The effective nuclear charge on Mg is smaller - on Ar the electrons are more strongly
attracted and therefore the electron cloud shrinks in towards the nucleus until the e-e
repulsions come into effect.
Consider the isoelectronic (they all have the same number of electrons) species Na+,
Mg2+, Ne, and F-, which of these has the smallest radius? Ans: Mg2+
All the species have the same number of electrons - but different number of protons.
Mg2+ has the highest proton to electron ratio and therefore the highest effective
nuclear charge and the strongest attraction between the protons and electrons - which
pulls the electron cloud towards the nucleus until the repulsions take effect.
When and where were the carbon and oxygen atoms in your body created? Ans:
Within stars and stellar explosions
Iodine exists as molecules of I2 and silicon dioxide exists as an extended network of
Silicon-oxygen bonds (similar to diamond). They both are solids at room temperature,
but which do you think has the higher melting point and why? Ans: Silicon dioxide
because to melt it you would have to break covalent bonds.
Does one molecule of water have a boiling point? Ans: No
Why does one molecule of water not have a boiling point? Ans: The boiling point is
the temperature at which the particles change from liquid to gas. If there is only one
particle the words liquid and gas (and solid for that matter) are meaningless.
Why do covalent bonds form? Ans: - Because electrons from one atom are attracted
to the nucleus of another atom.
- Because the formation of a bond results in a stable system that would require the
input of energy to change.
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Verified Answers
Which reaction requires the most energy?
A. N(g) → N+(g) + e -
B. N+(g) → N2+(g) + e -
C. F(g) → F+(g) + e -
D. F+(g) → F2+(g) + e - Ans: D. F+(g) → F2+(g) + e -
Fluorine has a higher effective nuclear charge than Nitrogen - so it is harder to remove
an electron (takes more energy because the electron is more strongly attracted by the
nucleus). Effective nuclear charge is the same for F and F+ because the number of
protons and core electrons are not changed. However, when the number of electrons
is reduced, the repulsion between electrons decreases which results in a decrease in
the radius of the electron cloud because the point at which attractions and repulsions
are balanced is closer to the nucleus when there is less repulsion. When the radius of
the electron cloud decreases, the strength of the attraction between the nucleus and
the valence electrons increases which increases the amount of energy required to
remove an electron (ionization energy).
Which has a larger atomic radius? Mg or Ar and why. Ans: Mg, because its valence
electrons are not as strongly attracted towards the nucleus as those in Ar.
, The effective nuclear charge on Mg is smaller - on Ar the electrons are more strongly
attracted and therefore the electron cloud shrinks in towards the nucleus until the e-e
repulsions come into effect.
Consider the isoelectronic (they all have the same number of electrons) species Na+,
Mg2+, Ne, and F-, which of these has the smallest radius? Ans: Mg2+
All the species have the same number of electrons - but different number of protons.
Mg2+ has the highest proton to electron ratio and therefore the highest effective
nuclear charge and the strongest attraction between the protons and electrons - which
pulls the electron cloud towards the nucleus until the repulsions take effect.
When and where were the carbon and oxygen atoms in your body created? Ans:
Within stars and stellar explosions
Iodine exists as molecules of I2 and silicon dioxide exists as an extended network of
Silicon-oxygen bonds (similar to diamond). They both are solids at room temperature,
but which do you think has the higher melting point and why? Ans: Silicon dioxide
because to melt it you would have to break covalent bonds.
Does one molecule of water have a boiling point? Ans: No
Why does one molecule of water not have a boiling point? Ans: The boiling point is
the temperature at which the particles change from liquid to gas. If there is only one
particle the words liquid and gas (and solid for that matter) are meaningless.
Why do covalent bonds form? Ans: - Because electrons from one atom are attracted
to the nucleus of another atom.
- Because the formation of a bond results in a stable system that would require the
input of energy to change.
© Get it right 2025 Getaway - Stuvia US All rights reserved
