Studied by 10 people
Molecular mimics
can produce similar effects as the naturally occurring molecules
What are the four most abundant elements found in living systems?
Hydrogen, oxygen, nitrogen, and carbon
The behavior of an atom depends on the
valence electrons in the outermost electron shell
The fact that oxygen is an atom that is strongly electronegative means that
it more strongly pulls shared electrons toward itself when forming a covalent bond with a less electronegative atom
Weak chemical bonds such as hydrogen bond
form when a hydrogen atom that is covalently bonded to an electronegative atom like oxygen or nitrogen is attracted to another electronegative atom
The molecular shape of a biological molecule is important because
it determines how biological molecules recognize and respond to one another
Which statement is true of all atoms that are anions?
The atom has more electrons than protons.
Trace elements
are required by an organism in minute quantities
When one or more pairs of valence electrons are shared by two neutral atoms, what type of bond is formed?
A covalent bond
Which of the following subatomic particles has appreciable mass and lacks a charge?
Neutron
Radioactive tracers
are important tools in biological research and medicine
Which of the following statements is true about chemical reactions?
They involve the making and breaking of chemical bonds.
A covalent bond
is the sharing of a pair of valence electrons by two atoms
In a process called radiometric dating, scientists measure the __________ of an isotope to determine the age of the Earth
half-life
Orbitals are best described as
a three-dimensional space where an electron spends most of its time with no more than 1 other electron, forming a pair
In ionic interactions
the transfer of valence electrons results in a completed valence shell for each ion
A covalent bond is likely to be polar if
one of the atoms sharing electrons is much more electronegative
When a very electronegative atom strips a valence electron away from its partner, __________ form.
ions
The number of protons in an uncharged atom
equals the number of electrons
When the proton number and electron number are unequal, the atom or molecule
is an ion
In chemical reactions, the __________ are the starting materials that are converted into the __________.
reactants; products
Nonpolar covalent bonds are always formed from atoms that are
equal in their electronegativity
Isotopes of an element will always differ in
atomic mass
Hydrogen bonds occur when
partial opposite charges on molecules come close enough to attract each other
Which of the following four statements, if any, is true regarding essential elements and living organisms?
Although all forms of life require iron, other elements are required only by certain species.
The reactivity of an atom arises from
the existence of unpaired electrons in the valence shell
The difference between a stable isotope and an unstable isotope of an element is that
the unstable isotope has a nucleus that decays spontaneously, is radioactive, and can be transformed into an atom of another element
Ionic bonds form as a result of
attraction between ions that have opposite charges
Which of the following has negligible mass?
electron
An acid is
a compound that donates hydrogen ions to a solution (1-6)
A substance that reduces the hydrogen ion concentration of a solution is
a base
The amount of heat required to change the temperature of 1 g of any substance by one °C is defined as
the specific heat of that substance
When ice forms, the __________ are farther apart than in liquid water, allowing the ice to form an organized crystal structure and float.
hydrogen bonds
Water is a polar molecule. This means that
the opposite ends of the molecule have opposite electrical charges
Glucose has a molecular mass of 180 daltons. To make a 2-molar (2 M) solution of glucose,
stir 360 g of glucose in water to dissolve the sugar, and then add enough water to bring the total volume of the solution up to 1 L
The specific heat of a substance is
the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C
Adding a base tends to __________ of a solution
lower the hydrogen ion concentration and increase the pH
Buffers are
substances that minimize changes in the concentration of H+ and OH- in a solution
Water molecules have __________ than molecules of similar size, such as ammonia and methane, reflecting its capacity to absorb large amounts of heat.
a higher boiling point
Adhesion is best described as
the clinging of one substance to another substance
When the pH of a solution shifts from 3 to 7, the hydrogen ion concentration has changed, and
it has decreased by 10,000 times
Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature?
The absorption of heat by the breaking of hydrogen bonds.
The ability of water molecules to form hydrogen bonds with other water molecules and water's ability to dissolve substances that have charges or partial charges are
both caused by water's partial charges
Nonpolar molecules that cluster away from water molecules are called __________ molecules.
hydrophobic
Sweating has a cooling effect because of water's high
heat of vaporization
__________ is an emergent property of water that allows insects like the raft spider to walk on water.
surface tension
Hydrophobic molecules
are uncharged, nonionic substances that seem to repel water
You can fill a glass of water to just slightly above the rim without it spilling over the glass. What property of water best explains this phenomenon?
surface tension
The partial charges on a water molecule occur because of
the unequal sharing of electrons between the hydrogen and the oxygen atoms of a water molecule
A solution at pH 10 contains __________ than the same amount of solution at pH 8.
100 times less H+
Hydrophilic molecules
are charged molecules that are attracted to the partial charge of the water molecule
The absorption of human-generated CO2 by the oceans
All of the listed responses are correct
Water moves up a plant because of hydrogen bonds by a process called _
cohesion and adhesion
A mole of methanol (CH3OH) weighs 32 g. The number of grams of methanol that are needed to produce 1 L of a 1 millimolar solution is
0.032 g
All of the following are hydrogen bonding properties except
nonpolar covalent bonding
The amount of heat required to convert 1 g of any substance from the liquid to the gaseous state is defined as
the heat of vaporization of that substance
Urine, at pH 6, contains __________ H+ as household bleach, at pH 13.
10,000,000 times as much
The phenomenon responsible for maintaining the upward movement of water through a vessel is
cohesion
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Flashcard (60)