Biology LS2
what does it mean when we say water is adhesive?
it is attracted to other polar molecules and ions
what is the temperature of a substance a measure of?
how fast its molecules are moving
electrons that are farther from the nucleus always have which of the following?
more potential energy
which of the following bonds involves the sharing of one or more pairs of electrons?
covalent bond
solid water is *blank* dense than liquid water
less
chemical bonds that form due to the attraction between oppositely charged atoms that have gained or lost electrons are what bonds?
ionic bonds
of the following list of bonds and interactions, which one is the weakest?
hydrophobic interaction
atoms are composed of a central nucleus which is surrounded by which orbiting particles?
electrons
what particles' number and cofiguration determines the chemical behavior of an atom?
electrons
in living organisms, almost all chemical reactions are catalyzed by protein catalysts called what?
enzymes
in living systems, which of the following catalyze almost every chemical reaction necessary for life?
enzymes
an element has five electrons in its outer shell. As such, it needs how many electrons to fill its outer energy level
3
the attraction of water to other polar substances
adhesion
ionic bonds involve which of the following?
an attraction between atoms with opposite electrical charges; a transfer of electrons from one atom to another
hydrogen bond
attraction between a covalently bound H atom with a slight positive charge and another covalently bound atom with a slight negative charge
ionic bond
attraction between oppositely charged atoms
what is a substance or a mixture of substances that act to resist changes in pH?
buffer
the number and configuration of electrons determines an element's what?
chemical properties
what bond is water consisting of one oxygen atom joined to two hydrogen atoms by two single polar bonds
covalent
rank the following bonds and interactions in order from strongest to weakest starting with the strongest at the top. When ranking the bonds, assume that they occur in a biological system, i.e. chemical compounds are dissolved in water.
covalent bond; ionic bond; hydrogen bond; hydrophobic interaction; van der waals attraction
a hydrogen bond can form between the partially negative *blank* atom of one water molecule and the partially positive *blank* atom of another water molecule
oxygen; hydrogen
substances or a mixture of substances known as buffers, act in living things to resist changes in what?
pH
if two atoms are joined by a polar covalent bond, what partial charge does the atom with the lower electronegativity have?
positive
the atoms in NaCl are held together by what type of bond?
ionic
a hydrogen ion, formed during the dissociation of water, has a charge of which of the following?
+1
when 1g of fructose is dissolved in 500mL of water, *blank* is the solvent and *blank* is the solute
water; fructose
van der waals attraction
weak attraction between atoms due to oppositely polarized electron clouds
anything that has mass and occupies space is defined as what?
matter
a group of atoms held together by chemical bonds in a stable association is called which of the following?
molecule
what is made of two or more atoms held together by chemical bonds in a stable association. the atoms may or may not belong to the same element
molecule
elements possessing all eight electrons (two for helium) in their outer energy level are said to be what?
noble gases; inert
hydrophobic interaction
nonpolar regions of a molecule are forced together in order to minimize contact with water molecules
atoms are composed of a central *blank* which is surrounded by orbiting *blank*
nucleus; electrons
where are valence electrons found?
in the outermost energy level only
what is the charge of a hydroxide ion?
-1
which of the following molecules is likely to have the highest specific heat and the highest heat of vaporization?
H2O
the amount of energy required to change 1g of a substance from a liquid to a gas is called which of the following?
heat of vaporization
the relatively weak, but numerous *blank* bonds that form between a water molecule and other molecules (including other water molecules) play a key role in determining the properties of water
hydrogen
which property of water strongly affects the overall shape of many biological molecules, such as protein, and DNA?
hydrophobic exclusion
chemical bonds that form due to the attraction between oppositely charged atoms that have gained or lost electrons are called what bonds?
ionic
electrons that are closer to the nucleus always have which of the following?
less potential energy
covalent bond
sharing of electron
when 1g of sugar is dissolved in 500mL of water, the sugar is called *blank* and water is called the *blank*
solute; solvent
what is the substance that measures how rapidly its individual molecules are moving?
temperature
when the pH of a solution rises by 1 which of the following happens?
the [H+] decreases 10-fold
when the pH of a solution falls by 2
the [H+] increases 100-fold
which of the following is the definition of the heat of vaporization of water?
the amount of energy needed to change 1g of water from a liquid to a gas
if two atoms are joined by a polar covalent bond, the shared electrons will tend to stay closer to the atom with which of the following characteristics?
the higher electronegativity
water is cohesive. Which describes this feature of water molecules?
they are attracted to each other
choose all statements that describes atoms that have unfilled electron shells?
they can form bonds with other atoms; they are chemically reactive; they can form chemical compounds
hydrogen bonds are important for which reasons?
they help maintain the structure of DNA and proteins; they play a key role in determining the properties of water
electrons in outer, unfilled energy levels are known as what?
valence electrons
