Deck 2: Atoms, Molecules, and Life

Question 1

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

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

Answer 1

C

Question 2

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

Answer 2

A

Question 3

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

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

Answer 3

E

Question 4

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

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

Question 5

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

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

Question 6

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

Question 7

Most biological molecules are joined by

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

Question 8

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

Question 9

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

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

Question 10

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

Question 11

An atomʹs nucleus is composed of

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

Question 12

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

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

Question 13

The atomic number of an atom is defined as the

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

Question 14

Free radicals are considered dangerous because they

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

Question 15

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

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

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) Neon (atomic number 10)
C) Magnesium (atomic number 12)
D) Helium (atomic number 2)

Question 17

Radioactive isotopes are biological tools that are often used to

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

Question 18

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

Question 19

Atoms or molecules that have gained or lost electrons are called

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

Question 20

The formation of ions involves the

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

Question 21

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

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

Question 22

The element carbon has atomic number 6. Carbon most likely

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

Question 23

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

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

Question 24

The hydrogen bond between two water molecules forms because water is

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

Question 25

What does H-O-H represent?

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

Question 26

Carbon has atomic number 6. Carbon most likely

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

Question 27

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

Question 28

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

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

Question 29

Polar molecules

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

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

Question 31

Which of the following is an example of hydrogen bonding?

A) The bond between O and H in a single molecule of water
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 of one water molecule and H of a separate water molecule
E) The bond between H of one water molecule and H of a separate water molecule

Question 32

Polar covalent bonds form when

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

Question 33

Which statement is an accurate description of water molecules?

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

Question 34

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

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

Question 35

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

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

Question 36

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 37

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

A) NaCl
B) H₂O
C) O₂
D) H₂
E) CH₄

Question 38

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

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

Question 39

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 40

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

A) Polar covalent
B) Ionic
C) Covalent

Question 41

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

Question 42

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

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

Question 43

Hydrophilic molecules

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

Question 44

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

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

Question 45

For ice to melt, it has to

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

Question 46

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 a base.
C) is an acid.
D) is hydrophobic.

Question 47

Sweating is a useful cooling mechanism for humans because water

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

Question 48

Water moves through a plant because of the property of

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

Question 49

A neutral solution

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

Question 50

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) H⁺ ion-donor levels increase.
C) Carbonic acid eats up the extra OH^- ions.
D) Bicarbonate (HCO3^-) accepts H⁺ ions and forms carbonic acid.

Question 51

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

A) separate into H⁺ and OH^- ions, which will react with the paper towel molecules.
B) move away from the towel because water molecules have hydrophobic interactions.
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) move up the towel because water molecules move quickly as it vaporizes.

Question 52

Water molecules are cohesive because they

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

Question 53

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 54

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

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

Question 55

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

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

Question 56

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

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

Question 57

What determines the cohesiveness of water molecules?

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

Question 58

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

Question 59

How do buffers work?

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

Question 60

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 61

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

Question 62

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

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

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

Question 65

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

Question 66

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

Question 67

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

Question 68

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

Question 69

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

Question 70

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

Question 71

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

Question 72

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

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

Question 73

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

Question 74

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

Question 75

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

Question 76

Which of the following is the densest?

A) Liquid water
B) Ice
C) Steam

Question 77

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

Question 78

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

Question 79

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

Question 80

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