test 1 homework questions and review sheets Flashcards
the tendency of an atom to pull electrons towards itself is referred to as its
electronegativity
a covalent chemical bond is one in which
outershell electrons are shared by two atoms so as to satisfactory fill the outer electron shells of both
bonds between 2 atoms that are equally electronegative are
nonpolar covalent bonds
in a single molecule of water, 2 hydrogen atoms are bonded to a single oxygen atom by
polar covalent bonds
the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus is a result from
partial negative charge in the water molecule
the partial negative charge at one end of a water molecule is attached and attracted to the partial positive charge of another water molecule. whats the attraction called?
hydrogen bond
to act as an effective coolant in a car’s radiator, a substance has to have the capacity to absorb a great deal of heat. In choosing a coolant for your car, which would you check first?
specific heat
which type of bonds must be broken for water to vaporize
hydrogen bonds
Why does ice float in liquid water?
Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water
Which of the following takes place as an ice cube cools a drink?
Kinetic energy in the liquid water decreases.
You have two beakers. One contains pure water, the other contains pure methanol. The covalent bonds of methanol molecules are nonpolar. You pour crystals of NaCl into each beaker. Predict what will happen.
NaCl crystals will dissolve readily in water but will not dissolve in methanol.
Which of the following solutions would require the addition of the greatest amount of base to bring the solution to neutral pH?
gastric juice at pH 2
One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+), as noted below.
H2CO3 HCO3- + H+
How does this system buffer the blood against decreases in pH?
the HCO3- acts as a base and removes excess H+ by the forming H2CO3
How many unpaired electrons does carbon need to complete its valence shell?
4
Which of the following is true of carbon?
It can form both polar and nonpolar bonds.
Why are hydrocarbons insoluble in water?
The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.
How do isomers differ from one another?
Isomers differ in the arrangement of bonding of atoms.
Which of the following best describes cis-trans isomers?
They differ in their spatial arrangement around inflexible double bonds.
Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?
Dehydration reactions assemble polymers; hydrolysis reactions break polymers apart.
How many molecules of water are used to completely hydrolyze a polymer that is 11 monomers long?
10
The molecular formula for glucose is C6H12O6. What would be the molecular formula for a molecule made by linking three glucose molecules together by dehydration reactions?
C18H32O16
What is the major structural difference between the starch amylopectin and glycogen?
the amount of branching that occurs in the molecule
Humans can digest starch but not cellulose because
humans have enzymes that can hydrolyze the α-glycosidic linkages (covalent bond between two α glucose monomers) of starch but not the β-glycosidic linkages (covalent bond between two β glucose monomers) of cellulose
Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?
as a disaccharide
Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?
disaccharide
Are lipids soluble or insoluble in water
insoluble
Phospholipids and triglycerides both _____.
have a glycerol backbone
