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