MDCB EXAM QUESTIONS AND ANSWERS. A+ GRADED
GUIDE.
electronegativity is larger/smaller with a greater number of electrons in the shell.
smaller
electronegativity us lager/smaller with a greater number of protons in a given period.
larger
List 4 pairs of 2 atoms that will create a polar covalent bond using H, C, O, N
C-O, H-O, N-H, C-N
In the box below, indicate what is wrong, if anything, with the following statement. If it is correct,
write "nothing, it is correct". If it is incorrect, rewrite it so it is correct. "When NaCl is dissolved in
water, the water molecules closest to the ions will tend to preferentially orient themselves so that
their oxygen atoms can interact electrostatically with the chloride ions and their hydrogen atoms can
interact electrostatically with the sodium ions."
When NaCl is dissolved in water, the water molecules closest to the ions will tend to preferentially
orient themselves so that the oxygen atoms interact with the sodium ions and the hydrogen atoms
interact with the
chloride ions.
What molecules are soluble in water.
A) Beta- carotene
B) serotonin
C) isobutane
D) Adrenalin
B and D, because they both have polar functional groups and can H-Bond with H2O
Which molecules are soluble in CH3(CH2)4CH3 (hexane)? Explain why they are soluble.
A) Beta- carotene
B) serotonin
C) isobutane
D) Adrenalin
A and C, because they are non polar and can be soluble in in a non polar solvent
Serotonin and adrenalin bind protein receptors displayed on the surface of the cell. What kinds of
chemical
bonds or interactions are most likely to form between serotonin and adrenalin and these protein
receptors?
Hydrogen bonding
, After the Cassini probe found water and simple organic molecules on one of Saturn's moons
(Enceladus),
scientists intentionally crashed the probe into Saturn. They were worried that Cassini could run out of
fuel and
crash into Enceladus, contaminating possible life forms or confounding future missions.
Scientists interested in life outside of earth have considered the idea that life could be based on
elements other
than carbon.
What is the name and valence of the atom you chose, and is it more or less electronegative than
carbon?
Si (silicon), valence is 4, LESS electronegative than carbon because it is bigger than carbon, with its
additional electron shell; the bigger the atom the lower the electronegativity
After the Cassini probe found water and simple organic molecules on one of Saturn's moons
(Enceladus),
scientists intentionally crashed the probe into Saturn. They were worried that Cassini could run out of
fuel and
crash into Enceladus, contaminating possible life forms or confounding future missions.
Scientists interested in life outside of earth have considered the idea that life could be based on
elements other
then carbon.
Scientists found water on Enceladus. It has a frozen, icy crust and a liquid underground ocean. The icy
crust is
a result of geysers that shoot warm water out from the underground ocean onto the surface where it
freezes.
How does the hydrogen bonding of water molecules in the icy crust differ from that in the geyser
water?
Water hydrogen bonds to 4 other water molecules in ice and the atoms form a crystalline lattice and are
further apart from each other than in liquid water. Water molecules in liquid water for 3 hydrogen
bonds with other water molecules and dynamic, moving while breaking and forming hydrogen bonds all
the time.
T/F van der Waals forces are similar to hydrogen bonding because they involve electrostatic
interactions
between opposite partial charges
True
T/F van der Waals forces are strong attractive forces that occur at a distance between hydrophilic
molecules
False
T/F van der Waals forces differ from hydrogen bonding in that they involve permanent dipole-dipole
False
GUIDE.
electronegativity is larger/smaller with a greater number of electrons in the shell.
smaller
electronegativity us lager/smaller with a greater number of protons in a given period.
larger
List 4 pairs of 2 atoms that will create a polar covalent bond using H, C, O, N
C-O, H-O, N-H, C-N
In the box below, indicate what is wrong, if anything, with the following statement. If it is correct,
write "nothing, it is correct". If it is incorrect, rewrite it so it is correct. "When NaCl is dissolved in
water, the water molecules closest to the ions will tend to preferentially orient themselves so that
their oxygen atoms can interact electrostatically with the chloride ions and their hydrogen atoms can
interact electrostatically with the sodium ions."
When NaCl is dissolved in water, the water molecules closest to the ions will tend to preferentially
orient themselves so that the oxygen atoms interact with the sodium ions and the hydrogen atoms
interact with the
chloride ions.
What molecules are soluble in water.
A) Beta- carotene
B) serotonin
C) isobutane
D) Adrenalin
B and D, because they both have polar functional groups and can H-Bond with H2O
Which molecules are soluble in CH3(CH2)4CH3 (hexane)? Explain why they are soluble.
A) Beta- carotene
B) serotonin
C) isobutane
D) Adrenalin
A and C, because they are non polar and can be soluble in in a non polar solvent
Serotonin and adrenalin bind protein receptors displayed on the surface of the cell. What kinds of
chemical
bonds or interactions are most likely to form between serotonin and adrenalin and these protein
receptors?
Hydrogen bonding
, After the Cassini probe found water and simple organic molecules on one of Saturn's moons
(Enceladus),
scientists intentionally crashed the probe into Saturn. They were worried that Cassini could run out of
fuel and
crash into Enceladus, contaminating possible life forms or confounding future missions.
Scientists interested in life outside of earth have considered the idea that life could be based on
elements other
than carbon.
What is the name and valence of the atom you chose, and is it more or less electronegative than
carbon?
Si (silicon), valence is 4, LESS electronegative than carbon because it is bigger than carbon, with its
additional electron shell; the bigger the atom the lower the electronegativity
After the Cassini probe found water and simple organic molecules on one of Saturn's moons
(Enceladus),
scientists intentionally crashed the probe into Saturn. They were worried that Cassini could run out of
fuel and
crash into Enceladus, contaminating possible life forms or confounding future missions.
Scientists interested in life outside of earth have considered the idea that life could be based on
elements other
then carbon.
Scientists found water on Enceladus. It has a frozen, icy crust and a liquid underground ocean. The icy
crust is
a result of geysers that shoot warm water out from the underground ocean onto the surface where it
freezes.
How does the hydrogen bonding of water molecules in the icy crust differ from that in the geyser
water?
Water hydrogen bonds to 4 other water molecules in ice and the atoms form a crystalline lattice and are
further apart from each other than in liquid water. Water molecules in liquid water for 3 hydrogen
bonds with other water molecules and dynamic, moving while breaking and forming hydrogen bonds all
the time.
T/F van der Waals forces are similar to hydrogen bonding because they involve electrostatic
interactions
between opposite partial charges
True
T/F van der Waals forces are strong attractive forces that occur at a distance between hydrophilic
molecules
False
T/F van der Waals forces differ from hydrogen bonding in that they involve permanent dipole-dipole
False
