exam 1 b

Question 1

A covalent chemical bond is one in which

Answer 1

outer-shell electrons of two atoms are shared so as to satisfactorily fill the outer electron shells of both atoms.

Question 2

What do atoms form when they share electron pairs?

Answer 2

molecules

Question 3

If an atom of sulfur (atomic number 16) were allowed to react with atoms of hydrogen (atomic number 1), which molecules would be formed

Answer 3

H-S-H

Question 4

When two atoms are equally electronegative, they will interact to form

Answer 4

nonpolar covalent bonds.

Question 5

What results from an unequal sharing of electrons between atoms?

Answer 5

a polar covalent bond

Question 6

Which of the following molecules contains the strongest polar covalent bond?

Answer 6

H2O

Question 7

What is the difference between covalent bonds and ionic bonds?

Answer 7

Covalent bonds involve the sharing of electrons between atoms, and ionic bonds involve the electrical attraction between atoms.

Question 8

What kind of a bond does NH4+ form with Cl- to make ammonium chloride salt (NH4Cl)?

Answer 8

ionic

Question 9

In a single molecule of water, the two hydrogen atoms are bonded to a single oxygen atom by

Answer 9

polar covalent bonds.

Question 10

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?

Answer 10

a hydrogen bond

Question 11

An example of a hydrogen bond is the bond between

Answer 11

the H of one water molecule and the O of another water molecule.

Question 12

Water is able to form hydrogen bonds because

Answer 12

the bonds that hold together the atoms in a water molecule are polar covalent bonds.

Question 13

Which of the following is possible due to the high surface tension of water?

Answer 13

A water strider can walk across the surface of a small pond.

Question 14

Which of the following is true when an ice cube cools a drink?

Answer 14

Kinetic energy in the drink decreases.

Question 15

Hydrophobic substances such as vegetable oil are

Answer 15

nonpolar substances that repel water molecules.

Question 16

If the pH of a solution is increased from pH 5 to pH 7, it means that the

Answer 16

concentration of OH- is 100 times greater than what it was at pH 5.

Question 17

Which property of the carbon atom gives it compatibility with a greater number of different elements than any other type of atom?

Answer 17

Carbon has a valence of 4.

Question 18

How many electron pairs does carbon share in order to complete its valence shell?

Answer 18

4

Question 19

Which of the following is (are) true about the carbon atoms present in all organic molecules?

Answer 19

They were incorporated into organic molecules by plants.
They were processed into sugars through photosynthesis.
They are ultimately derived from carbon dioxide.

Question 20

What is the reason why hydrocarbons are not soluble in water?

Answer 20

The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages.

Question 21

A compound contains hydroxyl groups as its predominant functional group. Which of the following statements is true concerning this compound?

Answer 21

It should dissolve in water.

Question 22

The tertiary structure of a protein is the

Answer 22

unique three-dimensional shape of the fully folded polypeptide.

Question 23

A strong covalent bond between amino acids that functions in maintaining a polypeptide’s specific three-dimensional shape is a (an)

Answer 23

disulfide bond.

Question 24

At which level of protein structure are interactions between the side chains (R groups. most important?

Answer 24

tertiary

Question 25

The R group or side chain of the amino acid serine is –CH2-OH. The R group or side chain of the amino acid alanine is –CH3. Where would you expect to find these amino acids in a globular protein in aqueous solution?

Answer 25

Alanine would be in the interior, and serine would be on the exterior of the globular protein.

Question 26

The globular protein transthyretin results from the aggregation of four polypeptide subunits. Each of the subunits is a polypeptide chain with an helix region. Which structure(s) must the transthyretin protein have?

Answer 26

primary, secondary, tertiary, and quaternary structure

Question 27

What would be an unexpected consequence of changing one amino acid in a protein consisting of 325 amino acids?

Answer 27

The primary structure of the protein would be changed. The tertiary structure of the protein might be changed. The biological activity or function of the protein might be altered.

Question 28

Large organic molecules are usually assembled by polymerization of a few kinds of simple subunits. Which of the following is an exception to this statement?

Answer 28

a steroid

Question 29

The element nitrogen is present in all of the following except

Answer 29

monosaccharides.