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Biology 1 Chapter 2 & 3
Terms in this set (22)
The type of bonding and the numbers of covalent bonds an atom can form with other atoms is determined by?
the number of unpaired electrons in the valence shell
The fullness of the valence shell determines the pattern of covalent bonding or ionization. The reactivity of an atom is a function of the presence of unpaired electrons in one or more orbitals of their valence shells.
Hydrogen bonding is most often seen?
when hydrogen is covalently bonded to an electronegative atom
Highly electronegative atoms attract shared electrons more strongly than hydrogen does, resulting in a slight positive charge on the hydrogen atom. The slightly positive hydrogen atom is then attracted to another electronegative atom, forming a hydrogen bond.
bonds between two atoms that are equally electronegative are?
nonpolar covalent bonds.
A covalent bond is likely to be polar if?
one of the atoms sharing electrons is much more electronegative than the other
Which statement about weak bonds is correct?
weak bonds are transient and easily reversible
Water molecules have a polarity, which allows them to be electrically attracted to other water molecules and other polar molecules by weak chemical bonds known as?
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by?
polar covalent bonds
The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called?
a hydrogen bond
The partial negative charge in a molecule of water occurs because?
The partial negative charge in a molecule of water occurs because the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus.
Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water's
High specific heat
the amount of heat it takes to raise the temperature of 1 gram of water by 1 degree Celsius; conversely, also the amount of heat that 1 gram of water releases when it cools by 1 degree Celsius
Many of water's emergent properties, such as its cohesion, its high specific heat, and its high heat of vaporization, result from the fact that water molecules?
are attracted to each other by partial negative and positive charges on the oxygen and hydrogen atoms, respectively
What do cohesion, surface tension, and adhesion have in common with reference to water?
All are properties related to hydrogen bonding.
Which of the following can be attributed to water's high specific heat?
A lake heats up more slowly than the air around it.
Why does ice float in liquid water?
Stable hydrogen bonds keep water molecules of ice farther apart than water molecules of liquid water.
Hydrophobic substances such as vegetable oil are?
Nonpolar substances that repel water molecules.
The following question is based on the figure of a solute molecule surrounded by a hydration shell of water.
Based on your knowledge of the polarity of water molecules, the solute molecule is most likely?
The loss of water from a plant by transpiration cools the leaf. Movement of water in transpiration requires both adhesion to the conducting walls and wood fibers of the plant and cohesion of the molecules to each other. A scientist wanted to increase the rate of transpiration of a crop species to extend its range into warmer climates. The scientist substituted a nonpolar solution with an atomic mass similar to that of water for hydrating the plants. What do you expect the scientist's data will indicate from this experiment?
Transpiration rates will fall to zero as nonpolar compounds do not have the properties necessary for adhesion and cohesion.
Which of the following statements is true about buffer solutions?
they maintain a relatively constant pH when either acids or bases are added to them.
What is the pH of normal rain?
slightly acidic because naturally present carbon dioxide from Earth's atmosphere dissolves in the raindrops to form carbonic acid.
How would acidification of seawater affect marine organisms?
Acidification would decrease dissolved carbonate concentrations and hinder growth of corals and shell-building animals.
Check all that apply
a. Water has a high specific heat due to the hydrogen bonding between water molecules.
b. Benzene is more resistant to temperature change than sulfuric acid.
c. More heat is required to raise the temperature of 1 g of water 1 ∘C than to raise the temperature of 1 g of ethyl alcohol 1 ∘C.
d. Sulfuric acid is less resistant to temperature change than water.
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