Deck 2: The Molecules of Life

Question 1

Explain why an atom that is NOT an ion is electrically neutral.

Answer 1

In an atom that is not an ion, the number of positively charged protons always equals the number of negatively charged electrons.

Question 2

The designation of a magnesium ion as Mg²⁺ indicates an atom that has:

A)two more protons than neutrons.
B)lost two electrons and is negatively charged.
C)lost two electrons and is positively charged.
D)gained two protons and is positively charged.
E)gained two protons and is negatively charged.

Answer 2

C

Question 3

Which of the following CORRECTLY pairs the particles of an atom with their physical properties?

A)proton-positively charged; neutron-uncharged; electron-negatively charged
B)proton-negatively charged; neutron-uncharged; electron-positively charged
C)proton-positively charged; neutron-negatively charged; electron-uncharged
D)proton-uncharged; neutron-negatively charged; electron-positively charged

Answer 3

A

Question 4

You discover an isotope of an element that has 6 electrons in its second and outermost shell, 8 protons, and 6 neutrons. What element is it?

A)fluorine (F)
B)carbon (C)
C)nitrogen (N)
D)oxygen (O)

Question 5

For an atom that is NOT an ion, which of the following must be TRUE?

A)The number of electrons equals the number of protons.
B)The number of electrons equals the number of neutrons.
C)The number of protons equals the number of neutrons.

Question 6

What would happen to an atom's atomic mass and electric charge if it gained or lost a proton, a neutron, or an electron?

Question 7

The atom:

A)is the basic unit of matter.
B)is the unit of composition for elements.
C)contains protons, neutrons, and electrons.
D)has negatively charged particles circling around a positively charged nucleus.
E)All of these choices are correct.

Question 8

The most common isotope of oxygen has an atomic mass of 16 (¹⁶O). An isotope with an atomic mass of 18 (¹⁸O) is also stable. How many valence electrons are present in ¹⁸O?

A)fewer than in ¹⁶O
B)more than in ¹⁶O
C)the same as in ¹⁶O
D)None of the other answer options is correct.

Question 9

How many electron orbitals does a carbon atom possess?

A)2
B)4
C)5
D)6
E)12

Question 10

List the particles in an atom, and indicate whether each is positively charged, negatively charged, or uncharged.

Question 11

The basic unit of matter is referred to as a(n) _____.

Question 12

The most common isotope of oxygen has 8 protons and an atomic mass of 16. How many electrons are present in the orbitals around an atom of oxygen?

A)2
B)4
C)6
D)8
E)10

Question 13

An atom with three electrons has:

A)one occupied orbital with three electrons.
B)two occupied orbitals, one of which has two electrons and the other has one.
C)three occupied orbitals, each of which contains one electron.
D)three energy shells, each of which contains one electron.

Question 14

¹⁴C is an isotope of carbon that possesses:

A)6 protons, 6 neutrons, and 2 electrons.
B)6 protons, 8 neutrons, and 6 electrons.
C)8 protons, 6 neutrons, and 2 electrons.
D)6 protons, 2 neutrons, and 6 electrons.
E)6 protons, 8 neutrons, and 2 electrons.

Question 15

Using the periodic table in Fig. 2.3, select the element that would be found in LEAST abundance in a living cell.

A)hydrogen (H)
B)sodium (Na)
C)phosphorous (P)
D)zinc (Zn)
E)silicon (Si)

Question 16

The most common isotope of oxygen has 8 protons and an atomic mass of 16. How many neutrons are present in the oxygen nucleus?

A)2
B)4
C)6
D)8
E)10

Question 17

The negatively charged components of atoms are referred to as:

A)protons.
B)electrons.
C)anions.
D)neutrons.
E)cations.

Question 18

If an atom has three electrons, how many occupied orbitals will the atom have, and how many electrons will be in each?

Question 19

What differentiates isotopes of the same element?

A)protons
B)neutrons
C)electrons
D)charge

Question 20

Sometimes, atoms gain or lose particles. The loss of which of the following results in a change of atomic mass?

A)a neutron
B)a proton
C)an electron
D)a neutron and a proton
E)a proton and an electron

Question 21

Which one of the following contributes to the measurement referred to as atomic mass?

A)protons and electrons
B)electrons and neutrons
C)protons, electrons, and neutrons
D)protons and neutrons
E)neutrons only

Question 22

What percentage of carbon's orbitals is spherical in conformation?

A)0%
B)20%
C)40%
D)80%
E)100%

Question 23

For the first three rows of the periodic table, elements in the same row have the same number and type of electron orbitals.

Question 24

Consider two carbon atoms, one represented as ¹⁴C and the other as ¹²C. Which of the following statements is TRUE regarding these two atoms?

A)These carbon atoms have the same number of protons.
B)These carbon atoms have the same number of neutrons.
C)These carbon atoms have different numbers of electrons.
D)These carbon atoms have different numbers of protons.

Question 25

A pair of atoms joined by a polar covalent bond:

A)has the charge spread evenly across both atoms.
B)has a slight positive charge on one atom and a slight negative charge on the other.
C)is unlikely to form hydrogen bonds with water.
D)mixes well with nonpolar solvents.

Question 26

Two elements within the same group:

A)occupy the same row on the periodic table of elements.
B)occupy the same column on the periodic table of elements.
C)have the same number of electrons in their outermost shell.
D)have different numbers of electrons in their outermost shell.
E)occupy the same column on the periodic table and have the same number of electrons in their outermost shell.

Question 27

Consider the two elements, sodium (Na) and magnesium (Mg), which occupy the same row in the periodic table of elements. Sodium and magnesium atoms have:

A)a different number of orbitals.
B)the same atomic number.
C)different atomic masses.
D)the same number of electrons in their outermost orbitals.
E)different atomic masses and the same number of electrons in their outermost orbitals.

Question 28

Nitrogen and phosphorus are in the same column of the periodic table. They have similar properties in bonding with other molecules because they have the same number of:

A)electrons.
B)paired electrons.
C)valence electrons.
D)electron shells.

Question 29

Refer to the periodic table, and decide which of the following molecules is held together by nonpolar covalent bonds.

A)NH₃
B)CO₂
C)KCl

Question 30

Of the following types of bonds between atoms, which is the STRONGEST?

A)ionic bond
B)hydrogen bond
C)covalent bond
D)van der Waals forces

Question 31

Refer to the periodic table, and decide which of the following molecules is held together by polar covalent bonds.

A)NH₃
B)CO₂
C)KCl

Question 32

Which of the following statements is TRUE regarding elements?

A)Elements are composed of several different types of atoms.
B)Elements are only found in nature and cannot be created by humans.
C)Elements are still categorized according to Aristotle's early classifications.
D)Elements are composed of only one type of atom.
E)Elements are only found in inorganic substances and not in living organisms.

Question 33

Which component of an atom has the SMALLEST mass?

A)proton
B)neutron
C)electron
D)isotope
E)isomer

Question 34

Which of the following bonds rely on the attraction of positive and negative charges?

A)ionic bonds
B)covalent bonds
C)hydrogen bonds
D)ionic bonds and hydrogen bonds
E)ionic bonds and covalent bonds

Question 35

Where is the highest-energy electron found in an atom of hydrogen?

A)in the spherical orbital closest to the nucleus
B)in the second spherical orbital, a little farther from the nucleus
C)in the dumbbell-shaped orbital of the y-axis
D)in the dumbbell-shaped orbital of the x-axis
E)in the dumbbell-shaped orbital of the z-axis

Question 36

Refer to the periodic table, and decide which of the following molecules is held together by ionic bonds.

A)NH₃
B)CO₂
C)KCl

Question 37

Which one of the following pairs would be classified as isotopes of each other?

A)H and H⁺
B)Na ⁺ and Cl^-
C)C and Si
D)¹²C and ¹³C
E)H and H⁺, Na⁺ and Cl^-, C and Si, ¹²C and ¹³C

Question 38

Which of the following statements is TRUE regarding atomic mass?

A)The atomic mass is defined as the sum of electrons and neutrons in an atom.
B)The atomic mass can be used to differentiate between different isotopes of the same element.
C)The atomic mass is synonymous with the atomic number.
D)The atomic mass is calculated by adding the total number of electrons, protons, and neutrons in an atom.

Question 39

Imagine that you have two different carbon atoms, one identified as ¹⁴C and the other as ¹³C. These two carbon atoms:

A)are two different carbon isotopes.
B)have a different number of neutrons.
C)have a different number of protons.
D)are two different carbon isotopes and have a different number of protons.
E)are two different carbon isotopes and have a different number of neutrons.

Question 40

The ability of atoms to form bonds is due largely to electrons farthest from the nucleus. These electrons are called _____ electrons.

Question 41

A molecule of common table salt, or NaCl, is the result of _____ bond forming between a sodium (Na) atom and a chlorine (Cl) atom.

A)an ionic
B)a covalent
C)a polar covalent
D)a hydrogen
E)either an ionic or a polar covalent

Question 42

The ability of atoms to attract electrons is referred to as:

A)van der Waals attraction.
B)potential energy.
C)hydrophobicity.
D)cohesion.
E)electronegativity.

Question 43

The _____ of a chemical reaction are transformed into different molecules called _____.

A)reactants; products
B)reactants; isomers
C)products; compounds
D)products; reactants
E)compounds; products

Question 44

Which of the following accurately describes a polar covalent bond?

A)the interaction of a hydrogen atom connected to an atom with a high electronegativity, and an electronegative atom of another molecule
B)the interaction of an atom with very high electronegativity, and an atom with very low electronegativity
C)the unequal sharing of electrons between an atom with a partial positive charge, and an atom with a partial negative charge
D)the equal sharing of electrons between atoms of identical or similar electronegativities
E)None of the other answer options is correct.

Question 45

Hydrogen bonding is ultimately due to differences in _____ between two atoms.

Question 46

When two atoms form a covalent bond, they share electrons from all of their orbitals. All of their orbitals, in turn, combine to form a single molecular orbital.

Question 47

A polar bond is due to:

A)equal sharing of valence electrons.
B)an attraction of opposite charges.
C)uneven sharing of electrons in a covalent bond.
D)the interaction between an ion and a non-ionic atom.
E)None of the other answer options is correct

Question 48

A(n) _____ is a substance composed of two or more atoms.

Question 49

A young girl is staring at the raindrops running down her window. She notices that the raindrops remain more or less intact, even as they cascade down the windowpane. This is a result of:

A)covalent bonds between water molecules.
B)oxygen bonds between water molecules.
C)polar covalent bonds between water molecules.
D)hydrogen bonds between water molecules.
E)ionic bonds between water molecules.

Question 50

An ionic bond is really a modified polar covalent bond, because two atoms "share" electrons when one atom steals a valence electron from the other.

Question 51

Which of the following is an example of a hydrogen bond?

A)the bond that forms between a hydrogen and oxygen atom within the same water molecule
B)the bond that forms between two hydrogen atoms within the same water molecule
C)the bond that forms between hydrogen and oxygen atoms within different water molecules
D)the bond that forms between two hydrogen atoms within different water molecules
E)the bond that forms between two oxygen atoms within different water molecules

Question 52

A pair of shared valence electrons is referred to as a(n):

A)ionic bond.
B)hydrogen bond.
C)van der Waals interaction.
D)covalent bond.
E)hydrophobic effect.

Question 53

A woman's doctor tells her to gargle with salt water. She stirs a tablespoon of salt into a cup of warm water and watches it dissolve. Why does the salt dissolve in water?

A)The positive hydrogen atoms in water molecules are attracted to chlorine ions.
B)The positive hydrogen atoms in water molecules are attracted to sodium ions.
C)The negative oxygen atoms in water molecules are attracted to chlorine ions.
D)The negative oxygen atoms in water molecules are attracted to sodium ions.
E)The positive hydrogen atoms in water molecules are attracted to chlorine ions, and the negative oxygen atoms in water molecules are attracted to sodium ions.

Question 54

Which one of the following is maintained during a chemical reaction?

A)the number of atoms present in the reactants
B)the identity of the atoms present in the reactants
C)the arrangement of chemical bonds present in the reactants
D)the number and identity of the atoms present in the reactants
E)the number and identity of the atoms, and the arrangement of chemical bonds present in the reactants.

Question 55

Which of the following statements regarding an atom with high electronegativity is TRUE?

A)It will have fewer protons than an atom with low electronegativity.
B)It will have a tendency not to attract electrons.
C)It will most likely be located on the left-most side of the periodic table of elements.
D)None of the other answer options is correct.

Question 56

The valence electrons of an atom are at the lowest energy level because their increased distance from the nucleus reduces their attraction to the atom's protons.

Question 57

An ionic interaction, such as the interaction between Na⁺ and Cl^-, is considered a covalent bond.

Question 58

Which one of the following elements is likely to form exactly three non-ionic interactions with hydrogen?

A)phosphorus
B)oxygen
C)carbon
D)sulfur
E)chlorine

Question 59

The structural formula for hydrogen gas (H₂) is represented as H-H. Here, the dash (-) represents a(n):

A)product.
B)reactant.
C)chemical reaction.
D)chemical bond.
E)electronegative bond.

Question 61

What is the chemical basis for water's role as the universal solvent?

A)Because water is polar, it disrupts most covalent bonds.
B)Because water is polar, it disrupts hydrogen bonds.
C)Because water is polar, it disrupts ionic bonds.
D)Because water is polar, it disrupts both covalent and hydrogen bonds.
E)Because water is polar, it disrupts both hydrogen and ionic bonds.

Question 62

The unique properties of water are due to the _____ of water molecules and the ability of water to form _____ with other water molecules and with other polar molecules.

A)electronegativity; polar covalent bonds
B)polarity; polar covalent bonds
C)polarity; hydrogen bonds
D)hydrophobicity; hydrogen bonds

Question 63

Water is able to dissolve many compounds as a result of which of the following?

A)the fact that water molecules are polar
B)the fact that water molecules are nonpolar
C)the fact that the hydrogen atoms in water molecules have a slight negative charge
D)the fact that most nonwater molecules are hydrophobic
E)the fact that water molecules are polar, and that the hydrogen atoms in water molecules have a slight negative charge

Question 64

You have an aqueous solution with a pH of exactly 7.0. What would you add to make the solution more acidic?

A)hydrogen chloride (HCl)
B)sodium hydroxide (NaOH)
C)sodium chloride (NaCl)
D)deionized water (dH₂O)

Question 65

You have an aqueous solution with a pH of 8.0. You add sodium chloride to a concentration of 1 gram per 100 milliliters. What happens to the pH?

A)It goes up.
B)It goes down.
C)It stays the same.
D)It depends on the temperature.

Question 66

Describe three chemical properties of water that make it uniquely suited for its role as a central "molecule of life."

Question 67

Which statement BEST describes an effect of the low density of frozen water in a lake?

A)When water freezes, it contracts, decreasing the water level in the lake.
B)Water in a lake freezes from the bottom up, killing most aquatic organisms.
C)When water in a lake freezes, it floats, providing insulation for organisms below the ice.
D)Water removes thermal energy from the land around a lake, causing the lake to freeze.

Question 68

Which of the following is NOT a property of water?

A)contracts during freezing
B)floats when solid
C)is a good solvent
D)adheres to polar compounds
E)is a polar molecule

Question 69

Which one of the following properties of water is primarily responsible for the ability of trees to draw water up from the roots to the leaves?

A)polarity
B)density
C)solvent capability
D)cohesion
E)pH neutrality

Question 70

Which one of the following represents the pH of a solution with the HIGHEST concentration of hydrogen ions?

A)1)0
B)4)5
C)7)0
D)9)1
E)11.5

Question 71

Part of the reason why salt dissolves in water is that hydrogen bonds form between water molecules and chlorine ions.

Question 72

The association of individual water molecules with other water molecules is called _____ and occurs through _____ bonds between water molecules.

A)adhesion; polar covalent
B)cohesion; polar covalent
C)cohesion; hydrogen bonds
D)adhesion; hydrogen bonds

Question 73

A water molecule contains what type of bond?

A)hydrogen
B)ionic
C)polar covalent
D)van der Waals interactions

Question 74

What is the chemical basis for water's role as the universal solvent?

Question 75

Which of the following statements about water is CORRECT?

A)Water is the most abundant molecule in living cells.
B)Water is a polar molecule.
C)Water has good solvent properties.
D)Water molecules form hydrogen bonds with other polar molecules.
E)All of these choices are correct.

Question 76

You have an aqueous solution with a pH of 6.0. What would you add to make the solution more basic?

A)Hydrogen chloride (HCl)
B)Sodium hydroxide (NaOH)
C)Sodium chloride (NaCl)
D)Deionized water (dH₂O)

Question 77

In a solution that has pH = 7.0, the ratio of protons (H⁺) to hydroxide ions (OH^-) equals

A)70
B)7
C)1
D)1/7
E)1/70

Question 78

Several chemical properties make water uniquely suited for its role as a central "molecule of life." Which of the following is FALSE?

A)Hydrogen bonding leads to high cohesiveness between water molecules.
B)Water resists temperature changes.
C)Water molecules are always polar.
D)The structure of a water molecule is stabilized by hydrogen bonds.
E)Water is a good solvent of polar molecules and ions.

Question 79

Which of the following statements is TRUE regarding a polar molecule?

A)A polar molecule is hydrophobic.
B)A polar molecule is hydrophilic.
C)A polar molecule will dissolve in water.
D)A polar molecule will not dissolve in water.
E)A polar molecule is hydrophilic and it will dissolve in water.

Question 80

Which one of the following statements about pH is INCORRECT?

A)An acidic solution has a higher concentration of protons than of hydroxide ions.
B)Physiological pH is defined as the pH of pure water, 7.0.
C)Some cellular compartments have different pH values than others.
D)The pH of a solution can range from 0 to 14.
E)A solution of pH 5 has a proton concentration 100 times greater than a solution of pH 7.