Chemistry HESI A2 Quizlet

Correct Answer: C

Rationale: The correct answer is C, atomic number. The atomic number represents the number of protons in an element. This is because the atomic number is the unique identifier of an element and determines its chemical properties. Protons are the positively charged particles in the nucleus of an atom, and the number of protons defines the element's identity. Explanation for incorrect choices: A: Atomic mass represents the average mass of all isotopes of an element, not the number of protons. B: Mass number is the sum of protons and neutrons in an atom, not just the number of protons. D: "Proton number" is not a standard term in chemistry, and it does not specifically refer to the number of protons in an element.

Correct Answer: B

Rationale: The correct answer is B: Weak. Dipole attraction is a type of intermolecular force where polar molecules are attracted to each other due to the positive and negative ends of their dipoles. This force is relatively weaker compared to other intermolecular forces like hydrogen bonding or ion-dipole interactions. It is weaker because it only involves the partial charges on molecules and not full charges like in ionic interactions. Choices A, C, and D are incorrect because dipole attractions are not as strong as those intermolecular forces that involve full charges or hydrogen bonding.

Correct Answer: B

Rationale: The correct answer is B: Physical. When no change is made to the chemical composition of a substance, it indicates a physical change. In physical changes, the substance retains its chemical identity and only its physical properties, such as shape, size, and state, are altered. This is because the particles in the substance rearrange or move without forming new substances. Choice A (Chemical) involves a change in the chemical composition, so it is incorrect. Choice C (Nuclear) involves changes at the atomic level, leading to different elements, which is not the case here. Choice D (Mechanical) involves changes in position and motion of objects, not relevant to the chemical composition of a substance.

Correct Answer: A

Rationale: The correct answer is A: Neutrons. Neutrons are neutral particles because they have no charge, unlike protons (positively charged), electrons (negatively charged), and cations (positively charged ions). Neutrons are found in the nucleus of an atom along with protons, contributing to the atomic mass without affecting the overall charge. This makes them essential for maintaining the stability of the nucleus. Therefore, neutral particles are called neutrons.

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.