Deck 2: Atoms, Molecules, and Life

Question 1

For an atom to achieve maximum stability and become chemically inert, what must occur?

A) Electron pairs are shared.
B) Its outermost energy shell must be completely filled with electrons.
C) Ionization occurs.
D) The number of electrons must equal the number of protons.

Answer 1

B

Question 2

Radioactive isotopes are biological tools that are often used to

A) detect brain tumors and other important medical technologies.
B) measure the size of fossils.
C) build up a store of calcium in a cell.
D) increase the pH of blood.

Answer 2

A

Question 3

The atomic number of an atom is defined as the

A) total number of energy shells.
B) number of protons in the atomic nucleus.
C) number of electrons in the outermost energy level.
D) total number of electrons and neutrons.
E) number of neutrons in the atomic nucleus.

Answer 3

B

Question 4

If a certain atom has a tendency to lose two electrons, that atom can then become a(n)

A) polar molecule.
B) water molecule.
C) ion.
D) isotope.

Question 5

Carbon- 14 is often used for carbon dating, where scientists measure the rate of carbon- 14 decay to determine the age of items. Carbon- 14 contains six protons and eight neutrons. During the process of carbon- 14 decay, one of its eight neutrons becomes a proton and an electron is emitted. Which of the following is the best explanation of what has occurred?

A) The resulting atom is still carbon- 14.
B) An ionic bond has formed.
C) The resulting atom is now a different element because the number of protons has changed.
D) The resulting atom has a more stable nucleus.

Question 6

The formation of sodium chloride (NaCl) is the result of

A) repelling between the same charges.
B) covalent bonding.
C) chemical unreactivity.
D) attraction between opposite charges.

Question 7

Most biological molecules are joined by

A) ionic bonds.
B) peptide bonds.
C) covalent bonds.
D) disulfide bonds.
E) hydrogen bonds.

Question 8

A substance with specific properties that cannot be broken down or converted into another substance is called a(n)

A) compound.
B) mixture.
C) element.
D) ion.
E) molecule.

Question 9

Free radicals are considered dangerous because they

A) steal electrons from other atoms, causing those atoms to become unstable.
B) damage oxygen and cause it to become an antioxidant.
C) emit dangerous radiation.
D) attack the atomic nucleus.

Question 10

Iron is an important element in human body cells. If iron has an atomic number of 26, what does this tell you about this element?

A) An iron atom has 13 protons and 13 neutrons.
B) An iron atom has 13 electrons and 13 protons.
C) An iron atom has 26 protons.
D) An iron atom is unable to become an isotope.

Question 11

Atoms or molecules that have gained or lost electrons are called

A) covalent.
B) acids.
C) ions.
D) buffers.
E) bases.

Question 12

The formation of ions involves the

A) gain or loss of electrons.
B) gain or loss of protons.
C) gain or loss of neutrons.
D) sharing of electrons.
E) sharing of protons.

Question 13

Imagine that you have been hired as a chemist and your first task is to examine a newly discovered atom. The paperwork you are given states that its atomic number is 110. What does this mean?

A) The atom contains 110 protons.
B) The atom contains 55 electrons.
C) The atom is an isotope.
D) The atom contains 55 protons and 55 neutrons.

Question 14

Sulfur is an essential element in the human body, and studying its characteristics is important in understanding human physiology. Sulfur atoms have six electrons in their outer shell. Based on this information, which of the following is TRUE?

A) Sulfur is inert.
B) Sulfur can form important molecules using covalent bonds.
C) Sulfur has eight electrons in its outer shell.
D) Sulfur is an important isotope of hydrogen.

Question 15

If you examined the human body on a chemical composition basis, which of the following combinations of elements would be most common?

A) O, C, N, Na
B) C, H, Ca, Cl
C) C, N, Ca, S
D) O, C, H, N
E) O, C, P, S

Question 16

Free radicals contain unpaired electrons in their outermost energy shell, so they react readily with other atoms or molecules to reach a more stable state. Which of the following could potentially be a free radical?

A) Fluorine (atomic number 9)
B) Helium (atomic number 2)
C) Magnesium (atomic number 12)
D) Neon (atomic number 10)

Question 17

Which four elements make up approximately 96% of living matter?

A) Carbon, hydrogen, nitrogen, oxygen
B) Oxygen, hydrogen, calcium, sodium
C) Carbon, phosphorus, hydrogen, sulfur
D) Carbon, sodium, chlorine, magnesium
E) Carbon, oxygen, calcium, sulfur

Question 18

Scientists recommend a diet rich in antioxidants to stay healthy. What occurs at the atomic level to explain this recommendation?

A) Antioxidants steal electrons, which gives cells extra energy.
B) Antioxidants prevent free radicals from attacking other atoms or molecules.
C) Antioxidants are inert and do not interact with free radicals.
D) Antioxidants cause an increase in pH, which is necessary for neutrality in cells.

Question 19

An atom's nucleus is composed of

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

Question 20

Phosphorus has an atomic number of 15, so what is the distribution of its electrons?

A) The first energy level has 2, the second has 8, and the third has 5.
B) The electron arrangement cannot be determined from the atomic number alone.
C) The first energy level has 2 and the second has 13.
D) The first energy level has 8 and the second has 7.
E) The first, second, and third energy levels have 5 electrons each.

Question 21

Hydrogen bonding can take place between a hydrogen atom and what other atom?

A) Hydrogen
B) Nitrogen
C) Oxygen
D) Nitrogen, oxygen, and fluorine
E) Fluorine

Question 22

Polar covalent bonds form when

A) more than one pair of electrons is shared.
B) electrons are shared unequally between atoms.
C) atoms from two molecules are repelling each other.
D) an acid and a base are combined.
E) ions are formed.

Question 23

Polar molecules

A) have an overall negative electric charge.
B) are always ions.
C) have an equal distribution of electric charge.
D) have an overall positive electric charge.
E) have an unequal distribution of electric charge.

Question 24

The element carbon has atomic number 6. Carbon most likely

A) forms four covalent bonds.
B) donates two electrons to another atom.
C) forms ionic bonds with other atoms.
D) shares two electrons with another atom.

Question 25

If sulfur has an atomic number of 16, how many covalent bonds can it form with other atoms?

A) Two
B) Four
C) Eight
D) Six
E) Zero

Question 26

Which of the following represents a molecule characterized by polar covalent bonding?

A) O₂
B) H₂O
C) H₂
D) NaCl
E) CH₄

Question 27

A single covalent chemical bond represents the sharing of how many electrons?

A) Six
B) One
C) Two
D) Three
E) Four

Question 28

The part of the atom that has the greatest biological interest and interactions with other atoms is the

A) neutron.
B) proton.
C) innermost electron shell.
D) electron.

Question 29

Which statement is an accurate description of water molecules?

A) They are uncharged and nonpolar.
B) They are charged and nonpolar.
C) They are slightly charged and polar.
D) They are ionically bonded.

Question 30

The atomic number of hydrogen is 1. Based on this fact, all of the following must be true of hydrogen gas (H₂) EXCEPT that it

A) is a stable molecule.
B) uses covalent bonds to form the molecule.
C) is a polar molecule.
D) shares one pair of electrons between the two hydrogen atoms.

Question 31

Which of the following best explains why a particular atom may not form compounds easily?

A) The atom has no electrons.
B) The atom's outer energy shells are completely full.
C) The atom has seven electrons in its outer shell.
D) The atom has an uneven number of protons.

Question 32

Carbon has atomic number 6. Carbon most likely

A) shares protons.
B) loses protons.
C) loses electrons.
D) shares neutrons.
E) shares electrons.

Question 33

Which of the following pairs has the most similar chemical properties to each other?

A) 16O and 32S
B) 12C and 14C
C) 12C and 28Si
D) 1H and 2He
E) 1H and 22Na

Question 34

Which of the following results from an unequal sharing of electrons between atoms?

A) Nonpolar covalent bond
B) Polar covalent bond
C) Ionic bond
D) Hydrogen bond
E) Electron- proton interaction

Question 35

Sodium (Na), atomic number 11, has a tendency to lose an electron in the presence of chlorine. After losing the electron, Na has protons in its nucleus.

A) 21
B) 22
C) 11
D) 10
E) 12

Question 36

What type of bond is easily disrupted in aqueous solutions (one in which the solvent is water)?

A) Ionic
B) Covalent
C) Polar covalent

Question 37

Which of the following is an example of hydrogen bonding?

A) The bond between H of one water molecule and H of a separate water molecule
B) The bond between O of one water molecule and O of a separate water molecule
C) The bond between the H of a water molecule and H of a hydrogen molecule
D) The bond between O and H in a single molecule of water
E) The bond between O of one water molecule and H of a separate water molecule

Question 38

Which of the following results from a transfer of electron(s) between atoms (e.g., NaCl)?

A) Nonpolar covalent bond
B) Polar covalent bond
C) Ionic bond
D) Hydrogen bond
E) Electron- proton interaction

Question 39

The hydrogen bond between two water molecules forms because water is

A) polar.
B) hydrophobic.
C) nonpolar.
D) a large molecule.
E) a small molecule.

Question 40

What does H- O- H represent?

A) Mixture including water
B) Ionic bonding of water
C) Molecule of water
D) Atom of water

Question 41

What is meant by the statement that water has a high specific heat?

A) Water freezes easily.
B) The boiling point of water is low.
C) It can absorb a lot of energy without changing temperature.
D) It grows hot quickly.
E) Water can heat up to only a certain temperature.

Question 42

Sweating is a useful cooling mechanism for humans because water

A) takes up a great deal of heat in changing from its solid state to its liquid state.
B) takes up a great deal of heat in changing from its liquid state to its gaseous state.
C) can exist in two states at temperatures common on Earth.
D) is an outstanding solvent.
E) ionizes readily.

Question 43

Which of the following best explains the attraction of water molecules to each other?

A) Nonpolar covalent bond
B) Polar covalent bond
C) Ionic bond
D) Hydrogen bond
E) Electron- proton interaction

Question 44

Water molecules are cohesive because they

A) form hydrogen bonds.
B) stick to other polar molecules.
C) make up 60% to 90% of an organism's body weight.
D) contain protons.
E) are repelled by nonpolar molecules.

Question 45

Which of the following is LEAST affected by the presence of water?

A) Nonpolar covalent bond
B) Polar covalent bond
C) Ionic bond
D) Hydrogen bond
E) Electron- proton interaction

Question 46

The human body must maintain a constant pH. In the blood, bicarbonate serves as a(n) to help maintain the necessary pH.

A) base
B) solvent
C) acid
D) buffer

Question 47

An atom of nitrogen attracts electrons more strongly than an atom of hydrogen. In an ammonia molecule (NH₃), which of the following best describes the electrical charge of the individual atoms?

A) The nitrogen becomes neutral.
B) The nitrogen is slightly more negative.
C) The hydrogens are strongly negative.
D) The nitrogen is slightly positive.
E) Charges balance out and none of the atoms has any charge.

Question 48

The fact that salt dissolves in water is best explained by the

A) hydrophobic nature of salt.
B) ionic nature of water molecules.
C) slightly charged nature of water molecules.
D) polar nature of water molecules.
E) hydrophobic nature of the water.

Question 49

For ice to melt, it has to

A) become less dense.
B) increase its heat of vaporization.
C) increase its property of cohesion.
D) absorb heat from its surroundings.

Question 50

Hydrophilic molecules

A) form hydrogen bonds among themselves.
B) do not readily dissolve in water.
C) are repelled by water.
D) readily dissolve in water.
E) are neutral and nonpolar.

Question 51

What happens when hydrochloric acid (HCl) dissociates in pure water?

A) The HCl molecules separate into H+ and Cl- ions.
B) The concentration of OH- ions increases.
C) The HCl molecules float on top of the water.
D) The pH of the solution increases.
E) The water has a decrease of H+ ions.

Question 52

Milk of magnesia is often used to treat stomach upset. It has a pH of 10. Based on this information, milk of magnesia

A) has the same pH as stomach acid.
B) is hydrophobic.
C) is an acid.
D) is a base.

Question 53

When the acidic level of human blood increases, how is the proper balance of hydrogen ions (H+) restored?

A) Bicarbonate (HCO₃- ) releases H+ ions that combine with excess OH- ions to form H₂O.
B) Carbonic acid eats up the extra OH- ions.
C) Bicarbonate (HCO₃- ) accepts H+ ions and forms carbonic acid.
D) H+ ion- donor levels increase.

Question 54

A neutral solution

A) has equal amounts of H+ and OH- .
B) has a pH of 0.
C) has no H+.
D) is hydrophobic.
E) has no OH- .

Question 55

If a substance measures 7 on the pH scale, that substance

A) may be lemon juice.
B) probably lacks OH- ions.
C) has a higher concentration of OH- than H+ ions.
D) is basic.
E) has equal concentrations of H+ and OH- ions.

Question 56

How do buffers work?

A) They convert H+ and OH- to water.
B) They accept and release OH- .
C) They accept and release H+.
D) They monitor the blood pH.
E) They soak up extra acid and base.

Question 57

Water moves through a plant because of the property of

A) cohesion.
B) high heat of fusion.
C) high heat of vaporization.
D) high specific heat.

Question 58

What determines the cohesiveness of water molecules?

A) Ionic bonds
B) Hydrophobic interactions
C) Covalent bonds
D) Hydrogen bonds

Question 59

Which of the following properties of water enable(s) it to function as a regulator of temperature for living organisms? (Hint: Think about what happens when you are sunbathing.)

A) High specific heat
B) Low specific heat
C) High heat of vaporization
D) High specific heat and low heat of vaporization
E) High specific heat and high heat of vaporization

Question 60

If you place a paper towel in a dish of water, the water will

A) move away from the towel because water molecules have hydrophobic interactions.
B) move up the towel because water molecules move quickly as it vaporizes.
C) dissolve the towel because water is a good solvent.
D) move up the towel as the water adheres to the paper towel while the cohesive water molecules stay bound to each other.
E) separate into H+ and OH- ions, which will react with the paper towel molecules.

Question 61

Water surface tension is a result of the cohesive nature of water molecules.

Question 62

The second electron shell is considered to be full when it contains electrons.

Question 63

You drop a handful of common table salt into a glass of water. Which of the following best describes what is happening inside the glass at the molecular level?

A) The positively charged hydrogen ends of the water molecules are attracted to sodium ions.
B) Sodium and chloride ions form a covalent bond.
C) The positively charged hydrogen ends of the water molecules are attracted to chloride ions.
D) Water and sodium form a covalent bond.

Question 64

The attractive force that holds two or more water molecules together is an example of an ionic bond.

Question 65

Which of the following is the densest?

A) Liquid water
B) Ice
C) Steam

Question 66

A basilisk lizard can run across the surface of a pond due to a property of water called .

Question 67

Most liquids become less dense upon solidification, but water is different in that it becomes denser when it solidifies.

Question 68

The chemical properties of an element are determined by the number of in its outermost energy shell.

Question 69

Unlike a rock, a reptile can sit in the hot sunshine without its body temperature soaring quickly. This is because the water in its body

A) is a good solvent.
B) is a poor solvent.
C) has a high specific heat.
D) has a low specific heat.

Question 70

Acids have pH values below 7, whereas bases have pH values above 7.

Question 71

Your friend does a belly flop into a swimming pool. The stinging pain he feels is most likely due to the

A) pH of the water.
B) surface tension of water (caused by the large number of hydrogen bonds that form between water molecules).
C) hydrophobic nature of your friend's skin.
D) fact that water is a good solvent.

Question 72

Ions and polar molecules that are electrically attracted to water molecules are .

Question 73

Isotopes are atoms of the same element that have different numbers of protons.

Question 74

If you place a feather on the surface of a bowl of water, the feather remains suspended on the surface due to the

A) polarity of the water.
B) fact that water is a good solvent.
C) density of the water.
D) surface tension of the water.

Question 75

To maintain a constant pH, buffers act to either accept or release H+.

Question 76

The specific heat of water is 10 times greater than that of iron. You place a metal pot full of water on the stove to heat it up. You touch the metal handle of the pot when the water is still only lukewarm. Which of the following best describes what happens?

A) You find that both the water and the handle are the same temperature.
B) You determine that metal pots full of water produce acids and bases.
C) You find that the handle is cooler than the water in the pot.
D) You burn your finger and pull your hand away from the hot metal handle.

Question 77

In general, a substance that carries an electric charge can dissolve in water. Given this fact, which of the following would most likely NOT dissolve in water?

A) Ionic compounds
B) NaCl
C) Nonpolar molecules
D) Polar covalent molecules

Question 78

Isotopes are atoms of the same element that have different numbers of _ .

Question 79

Every atom of the same element has an equal number of electrons and protons.

Question 80

When water freezes, stable hydrogen bonds form between the water molecules that create an open, six- sided (hexagonal) arrangement.