Chemistry HESI A2 Quizlet

Correct Answer: C

Rationale: The correct answer is C: Atomic mass. Atomic mass refers to the average mass of an element's isotopes as they occur in nature. This is calculated by taking into account the abundance of each isotope. The atomic number (A) is the number of protons in an atom's nucleus, not the average mass. The mass number (B) is the sum of protons and neutrons in an atom's nucleus, not the average mass. Neutron number (D) is simply the number of neutrons in an atom's nucleus, not the average mass. Therefore, the correct term for the average mass of isotopes is atomic mass.

Correct Answer: C

Rationale: The correct answer is C: Hydrogen bonding. Hydrogen bonding is the strongest intermolecular force due to the high electronegativity difference between hydrogen and elements like nitrogen, oxygen, or fluorine, leading to a strong partial positive charge on hydrogen. This allows for a strong attraction with the partial negative charge on the electronegative atom of another molecule. Dipole interactions (A) are weaker than hydrogen bonding, dispersion forces (B) are the weakest intermolecular force, and Van der Waals forces (D) are a broad term that encompasses all intermolecular forces, including hydrogen bonding.

Correct Answer: B

Rationale: Stoichiometry is the study of mass relationships in chemical reactions. It involves calculating the quantities of reactants and products. By using balanced chemical equations, one can determine the amounts of substances involved. This answer is correct because it directly relates to the main concept of stoichiometry. Explanation for other choices: A: The study of energy changes in chemical reactions - This is incorrect as it refers to the field of thermodynamics. C: The study of atomic structure - This is incorrect as it pertains to atomic theory and not the mass relationships in reactions. D: The study of molecular geometry - This is incorrect as it deals with the spatial arrangement of atoms in molecules, not the mass relationships in reactions.

Correct Answer: C

Rationale: Step-by-step rationale for why choice C (Aluminum foil) is correct: 1. Beta radiation particles are high-energy electrons or positrons. 2. Aluminum foil has a high atomic number and density, making it effective at stopping beta particles. 3. The electrons in the aluminum atoms interact with the beta particles, causing them to lose energy and stop. 4. Being thin and dense, aluminum foil can effectively block beta radiation particles. Summary of why other choices are incorrect: A. Plastic: Plastic is not dense enough to effectively stop beta particles. B. Glass: While glass is denser than plastic, it is not as effective as aluminum foil in stopping beta radiation. D. Concrete: Concrete is dense, but it is not as effective as aluminum foil in stopping beta particles due to its composition and thickness.

Correct Answer: B

Rationale: The correct answer is B: Ionic & covalent. Ionic bonding involves the transfer of electrons between atoms, resulting in the formation of positive and negative ions. Covalent bonding involves the sharing of electrons between atoms. These two types of bonding are distinct in their electron behavior and resulting bond strength. Choice A is incorrect as hydrogen bonding is a type of intermolecular force, not a primary chemical bond. Choice C is incorrect as hydrogen bonding is not a primary chemical bond and ionic bonding involves the transfer of electrons, not hydrogen atoms. Choice D is incorrect as metallic bonding involves the sharing of electrons in a sea of electrons, not between specific atoms.