Chapter 2
Which of the following effects can occur because of the high surface tension of water?
A raft spider can walk across the surface of a small pond.
Which drawing in the figure depicts an atom with 6 valence electrons?
C ; 6 in outer shell
_____ atoms give organic molecules their overall shape; _____ atoms determine the overall chemical behavior of organic molecules.
Carbon; H, N, and O
What is the difference between covalent bonds and ionic bonds?
Covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between charged atoms.
During chemical evolution, which of the following occurred in the molecules involved?
Entropy decreased while potential energy increased.
Which of the following is TRUE of carbon?
It can form both polar and nonpolar bonds.
Which of the following takes place as an ice cube cools a drink?
Kinetic energy in the liquid water decreases.
Why are some reactions exothermic?
The products have lower potential energy than the reactants.
Why do chemical reactions tend to speed up when the concentration of the reactants is increased?
The reactants collide more often.
Ice melts spontaneously at room temperature, even though the process is endothermic. How is this possible?
There is a large increase in entropy
What results from the chemical reaction illustrated above? the reactants have no charge
a cation with a net charge of +1 and an anion with a net charge of -1
Elements found on the left side of the periodic table contain outer shells that are ___; these elements tend to form ___ in solution.
almost empty; cations
Which of the functional groups below acts most like an acid in water?
carboxyl
The first chemicals that provided potential energy on Earth may have been formaldehyde and hydrogen cyanide. While these were produced by sunlight-driven reactions, they also occurred around deep-sea vents. If the first organisms on Earth evolved around these vents, the first life on Earth was _____.
chemosynthetic, obtaining energy from chemicals
A carbon atom is most likely to form what kind of bond(s) with other atoms?
covalent
A strong acid like HCl
dissociates completely in an aqueous solution
Which of the following is a property of liquid water? Liquid water:
has a heat of vaporization that is higher than that for most other substances
Which type of bond must be broken for water to vaporize?
hydrogen bonds
You need to write down information about a molecule, but need to indicate only the type and number of atoms it contains. Which representation would work best?
molecular formula
Bonds between two atoms that are equally electronegative are _____.
nonpolar covalent bonds
A covalent bond is likely to be polar when
one of the atoms sharing electrons is much more electronegative than the other atom
Which of the following pairs of neutral atoms would be most likely to form ions and thus an ionic bond?
one with 7 on outer and another with 1 on outer
Stanley Miller's 1953 experiments supported the hypothesis that:
organic molecules can be synthesized abiotically under conditions that may have existed in early earth
A covalent bond is one in which:
outer-shell electrons of two atoms are shared so as to satisfactorily fill their respective orbitals
In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by
polar covalent bonds
Based on your knowledge of the polarity of water molecules, the solute molecule depicted here is most likely:
positively charged
An atom has four electrons in its valence shell. What types of covalent bonds is it capable of forming?
single, double, or triple bonds
Which of the following is the most spontaneous reaction? A reaction that is:
slightly exothermic and leads to a huge increase in entropy
You need to represent a molecule to best illustrate the relative sizes of the atoms involved and their interrelationships. Which representation would work best?
space-filling model
Which of the following correctly describes a reaction that has reached chemical equilibrium?
the rate of the forward reaction is equal to the rate of the reverse reaction