Chemistry HESI A2 Quizlet

Correct Answer: C

Rationale: The correct answer is C: +2. Alpha radiation particles are helium nuclei consisting of 2 protons and 2 neutrons, giving them a charge of +2. This charge is due to the presence of 2 protons, which are positively charged particles. Choice A (-2) is incorrect as alpha particles are positively charged. Choice B (0) is incorrect as alpha particles have a positive charge. Choice D (+1) is incorrect as alpha particles have a charge of +2 due to the presence of 2 protons.

Correct Answer: B

Rationale: The correct answer is B: Alpha. Alpha radiation involves the emission of helium ions, which are essentially helium atoms that have lost two electrons. This type of radiation consists of alpha particles, which are positively charged and relatively heavy. They have low penetration power and can be stopped by a sheet of paper or human skin. Beta radiation (choice A) involves the emission of high-energy electrons or positrons, not helium ions. Gamma radiation (choice C) consists of electromagnetic waves and does not involve the emission of particles. There is no radiation type known as Delta (choice D). Therefore, the correct answer is B as it accurately describes the characteristics of alpha radiation.

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: A

Rationale: The correct answer is A: Stoichiometry. Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. It involves calculating the amount of substances consumed and produced in a reaction based on balanced chemical equations. This includes determining the mole ratios, mass relationships, and volume relationships in a reaction. Choice B (Molecular chemistry) focuses on the structure and properties of molecules, not specifically on quantities in reactions. Choice C (Atomic chemistry) deals with the study of atoms and their properties, not the quantities in reactions. Choice D (Thermodynamics) concerns energy changes in chemical reactions, not the quantitative relationships between compounds. Therefore, stoichiometry is the correct choice for this question.

Correct Answer: D

Rationale: The correct answer is D: Color of the reactants. The color of the reactants does not affect the reaction rate as it is a purely visual characteristic and does not influence the speed at which the reaction occurs. Temperature affects reaction rate by providing energy for molecules to react faster. Surface area influences reaction rate by increasing the area of contact between reactants. Concentration of reactants affects reaction rate by increasing the frequency of collisions between molecules. In summary, factors like temperature, surface area, and concentration directly impact reaction rate, whereas color is merely a visual property and does not play a role in determining the speed of a chemical reaction.