Chapter 2 - Chemical Level of Organization Flashcards
(34 cards)
Together, just four elements make up more than 95 percent of the body’s mass. These include (BLANK).
A) Calcium, Magnesium, Iron, and Carbon.
B) Oxygen, Calcium, Iron, and Nitrogen.
C) Sodium, Chlorine, Carbon, and Hydrogen.
D) Oxygen, Carbon, Hydrogen, and Nitrogen.
Correct Answer: D) Oxygen, Carbon, Hydrogen, and Nitrogen.
Explanation: These four elements make up the bulk of the human body’s mass because they are essential components of water, proteins, nucleic acids, and other organic molecules.
Incorrect Answers:
A) Includes important trace elements, but they are not the most abundant.
B) Oxygen and nitrogen are major elements, but calcium and iron are less abundant.
C) Sodium and chlorine are vital electrolytes but present in smaller amounts.
The smallest unit of an element that still retains the distinctive behavior of that element is an (BLANK).
A) Electron.
B) Atom.
C) Elemental Particle.
D) Isotope.
Correct Answer: B) Atom.
Explanation: An atom retains the chemical properties of an element and cannot be broken down further by chemical means.
Incorrect Answers:
A) An electron is a subatomic particle, not the full unit of an element.
C) “Elemental particle” is not a standard term in this context.
D) An isotope is a variation of an atom, not the smallest unit itself.
The characteristic that gives an element its distinctive properties is its number of (BLANK).
A) Protons.
B) Neutrons.
C) Electrons.
D) Atoms.
Correct Answer: A) Protons.
Explanation: The number of protons determines the atomic number, which defines the identity of the element.
Incorrect Answers:
B) Neutrons vary in isotopes but do not change the element.
C) Electrons influence charge but not identity.
D) The number of atoms is not a defining characteristic of an element.
On the periodic table of the elements, mercury (Hg) has an atomic number of 80 and a mass number of 200.59. It has seven stable isotopes. The most abundant of these probably have (BLANK).
A) About 80 neutrons each.
B) Fewer than 80 neutrons each.
C) More than 80 neutrons each.
D) More electrons than neutrons.
Correct Answer: C) More than 80 neutrons each.
Explanation: The mass number minus the atomic number gives the approximate number of neutrons. 200 – 80 = 120 neutrons.
Incorrect Answers:
A) About 80 neutrons would be too low for the given mass.
B) Fewer than 80 would result in a much lower mass number.
D) Atoms are neutral unless ionized, so protons = electrons; not more electrons than neutrons.
Nitrogen has an atomic number of seven. How many electron shells does it likely have?
A) One.
B) Two.
C) Three.
D) Four.
Correct Answer: B) Two.
Explanation: The first shell holds 2 electrons, and the second holds up to 8. Nitrogen has 7 electrons, so two shells are needed.
Incorrect Answers:
A) Only 2 electrons fit in the first shell.
C & D) More shells are unnecessary for 7 electrons.
Which of the following is a molecule, but not a compound?
A) H₂O.
B) 2H.
C) H₂.
D) H⁺.
Correct Answer: C) H₂.
Explanation: A molecule is two or more atoms bonded together. H₂ is two hydrogen atoms bonded (same element), so it’s a molecule but not a compound.
Incorrect Answers:
A) H₂O is a compound (different elements).
B) 2H refers to two separate hydrogen atoms, not a molecule.
D) H⁺ is a single ion, not a molecule.
Oxygen has an atomic number of eight. How many electron shells does it likely have?
A) Four.
B) Two.
C) Three.
D) One.
Correct Answer: B) Two.
Explanation: Oxygen has 8 electrons. The first shell holds 2, and the second holds up to 8—so oxygen uses two shells.
Incorrect Answers:
A) Four shells would require more than 18 electrons.
C) Three shells would be needed for elements with more than 10 electrons.
D) One shell only holds 2 electrons—not enough for oxygen’s 8.
A molecule of ammonia contains one atom of nitrogen and three atoms of hydrogen. These are linked with (BLANK).
A) Ionic bonds.
B) Nonpolar covalent bonds.
C) Polar covalent bonds.
D) Hydrogen bonds.
Correct Answer: C) Polar covalent bonds.
Explanation: Nitrogen is more electronegative than hydrogen, so it shares electrons unequally, creating a polar covalent bond.
Incorrect Answers:
A) Ionic bonds involve electron transfer, not sharing.
B) Nonpolar bonds involve equal sharing.
D) Hydrogen bonds are weak attractions between molecules, not within ammonia.
When an atom donates an electron to another atom, it becomes
A) An ion.
B) An anion.
C) Nonpolar.
D) All of the above.
Correct Answer: A) An ion.
Explanation: Losing or gaining electrons turns an atom into an ion. Donating an electron results in a positively charged cation.
Incorrect Answers:
B) An anion gains electrons, not loses them.
C) “Nonpolar” refers to electron sharing, not transfer.
D) Only “ion” is correct in this context.
A substance formed of crystals of equal numbers of cations and anions held together by ionic bonds is called a(n) (BLANK).
A) Noble gas.
B) Salt.
C) Electrolyte.
D) Dipole.
Correct Answer: B) Salt.
Explanation: Salts are ionic compounds that form crystals of cations and anions.
Incorrect Answers:
A) Noble gases are unreactive and do not form such bonds.
C) Electrolytes are ions in solution, not necessarily in crystal form.
D) Dipole refers to polar molecules, not ionic crystals.
Which of the following statements about chemical bonds is true?
A) Ionic bonds are stronger than covalent bonds.
B) Hydrogen bonds occur between two atoms of hydrogen.
C) Bonding readily occurs between nonpolar and polar molecules.
D) A molecule of water is unlikely to bond with an ion.
Correct Answer: C) Bonding readily occurs between nonpolar and polar molecules.
Explanation: Polar and nonpolar molecules can interact under certain conditions, though generally like dissolves like.
Incorrect Answers:
A) Covalent bonds are typically stronger in biological systems.
B) Hydrogen bonds involve hydrogen and an electronegative atom, not two hydrogens.
D) Water (polar) interacts well with ions—this is how it dissolves salts.
Which chemical bond shares electrons that then complete their valence shell?
A) Polar.
B) Covalent.
C) Hydrogen.
D) Ionic.
Correct Answer: B) Covalent.
Explanation: Covalent bonds form when atoms share electrons, allowing each atom to complete its valence shell.
Incorrect Answers:
A) Polar describes a type of covalent bond where electrons are shared unequally, but the key concept is covalent.
C) Hydrogen bonds are weak attractions between molecules—not shared electrons.
D) Ionic bonds involve electron transfer, not sharing.
A molecule of water contains one atom of oxygen and two atoms of hydrogen. These are linked with (BLANK).
A) Hydrogen bonds.
B) Polar covalent bonds.
C) Ionic bonds.
D) Nonpolar covalent bonds.
Correct Answer: B) Polar covalent bonds.
Explanation: In a water molecule (H₂O), oxygen shares electrons with hydrogen atoms unequally, creating polar covalent bonds.
Incorrect Answers:
A) Hydrogen bonds occur between water molecules, not within a single molecule.
C) Ionic bonds involve complete electron transfer, not sharing.
D) Nonpolar covalent bonds involve equal sharing of electrons, which is not the case in water.
The energy stored in a foot of snow on a steep roof is (BLANK).
A) Potential energy.
B) Kinetic energy.
C) Radiant energy.
D) Activation energy.
Correct Answer: A) Potential energy.
Explanation: It’s stored energy due to the snow’s position (gravitational potential).
Incorrect Answers:
B) Kinetic is energy of motion, not at rest.
C) Radiant energy is light or electromagnetic.
D) Activation energy is the energy needed to start a chemical reaction.
The bonding of calcium, phosphorus, and other elements produces mineral crystals that are found in bone. This is an example of a(n) (BLANK) reaction.
A) Catabolic.
B) Synthesis.
C) Decomposition.
D) Exchange.
Correct Answer: B) Synthesis.
Explanation: Synthesis reactions build larger structures from smaller components.
Incorrect Answers:
A) Catabolic breaks down molecules.
C) Decomposition is the opposite of synthesis.
D) Exchange swaps components between molecules.
AB → A + B is a general notation for a(n) (BLANK) reaction.
A) Anabolic.
B) Endergonic.
C) Decomposition.
D) Exchange.
Correct Answer: C) Decomposition.
Explanation: One molecule splits into two or more.
Incorrect Answers:
A) Anabolic builds molecules.
B) Endergonic refers to energy absorbed, not structure.
D) Exchange involves both building and breaking.
(BLANK) reactions release energy.
A) Catabolic.
B) Exergonic.
C) Decomposition.
D) Catabolic, Exergonic, and Decomposition.
Correct Answer: D) Catabolic, Exergonic, and Decomposition.
Explanation: All these reactions involve breaking bonds and releasing energy.
Incorrect Answers:
A, B, C individually are true, but D encompasses all correct options.
Which of the following combinations of atoms is most likely to result in a chemical reaction?
A) Hydrogen and Hydrogen.
B) Hydrogen and Helium.
C) Helium and Helium.
D) Neon and Helium.
Correct Answer: A) Hydrogen and Hydrogen.
Explanation: Hydrogen atoms can bond to form H₂ through covalent bonding.
Incorrect Answers:
B, C, D) Helium and Neon are noble gases—chemically inert.
Chewing a bite of bread mixes it with saliva and facilitates its chemical breakdown. This is most likely due to the fact that (BLANK).
A) The inside of the mouth maintains a very high temperature.
B) Chewing stores potential energy.
C) Chewing facilitates synthesis reactions.
D) Saliva contains enzymes.
Correct Answer: D) Saliva contains enzymes.
Explanation: Enzymes in saliva begin the breakdown of starch into simpler sugars.
Incorrect Answers:
A) Body temperature is not sufficient alone for breakdown.
B) Chewing is mechanical, not about storing energy.
C) Digestion involves decomposition, not synthesis.
The energy stored in a ball at the top of a hill is (BLANK).
A) Radiant energy.
B) Kinetic energy.
C) Potential energy.
D) Activation energy.
Correct Answer: C) Potential energy.
Explanation: Potential energy is stored energy based on position. The ball has energy due to its height, which can be converted into motion.
Incorrect Answers:
A) Radiant energy is energy from light or electromagnetic waves.
B) Kinetic energy is energy of motion; the ball isn’t moving yet.
D) Activation energy refers to the energy required to initiate a chemical reaction—not relevant to physical position.
Which of the following is most likely to be found evenly distributed in water in a homogeneous solution?
A) Sodium ions and chloride ions.
B) NaCl molecules.
C) Salt crystals.
D) Red blood cells.
Correct Answer: A) Sodium ions and chloride ions.
Explanation: In a true solution, NaCl dissociates into Na⁺ and Cl⁻, which are evenly distributed in the solvent (water).
Incorrect Answers:
B) NaCl molecules do not remain intact in water.
C) Salt crystals settle out, indicating a heterogeneous mixture.
D) Red blood cells form a suspension, not a solution.
Jenny mixes up a batch of pancake batter, then stirs in some chocolate chips. As she is waiting for the first few pancakes to cook, she notices the chocolate chips sinking to the bottom of the clear glass mixing bowl. The chocolate-chip batter is an example of a (BLANK).
A) Solvent.
B) Solute.
C) Solution.
D) Suspension.
Correct Answer: D) Suspension.
Explanation: Suspensions contain large particles that settle out over time, like chocolate chips in batter.
Incorrect Answers:
A) A solvent is the dissolving medium, not the mixture.
B) Solute refers to the substance being dissolved.
C) A solution would have evenly distributed components.
A substance dissociates into K⁺ and Cl⁻ in solution. The substance is a(n) (BLANK).
A) Acid.
B) Base.
C) Salt.
D) Buffer.
Correct Answer: C) Salt.
Explanation: Salts are ionic compounds that dissociate into cations and anions (like K⁺ and Cl⁻) without forming H⁺ or OH⁻.
Incorrect Answers:
A) Acids release H⁺ in solution.
B) Bases release OH⁻ or accept H⁺.
D) Buffers resist pH changes but are typically weak acids/bases, not salts.
Ty is three years old and as a result of a “stomach bug” has been vomiting for about 24 hours. His blood pH is 7.48. What does this mean?
A) Ty’s blood is slightly acidic.
B) Ty’s blood is slightly alkaline.
C) Ty’s blood is highly acidic.
D) Ty’s blood is within the normal range.
Correct Answer: B) Ty’s blood is slightly alkaline.
Explanation: A normal blood pH is about 7.35–7.45. A pH of 7.48 is slightly above that, indicating alkalosis.
Incorrect Answers:
A & C) A pH below 7.35 would be acidic.
D) 7.48 is above the normal range.
