CEM 141 MSU EXAM PREP TEST BANK
VERIFIED QUESTIONS AND CORRECT
ANSWERS
●● Which has a larger atomic radius? Mg or Ar and why.
Answer: 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?
Answer: 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?
Answer: 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?
Answer: Silicon dioxide because to melt it you would have to break
covalent bonds.
●● Does one molecule of water have a boiling point?
Answer: No
●● Why does one molecule of water not have a boiling point?
Answer: 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?
Answer: - 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.
VERIFIED QUESTIONS AND CORRECT
ANSWERS
●● Which has a larger atomic radius? Mg or Ar and why.
Answer: 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?
Answer: 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?
Answer: 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?
Answer: Silicon dioxide because to melt it you would have to break
covalent bonds.
●● Does one molecule of water have a boiling point?
Answer: No
●● Why does one molecule of water not have a boiling point?
Answer: 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?
Answer: - 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.
