Chemistry HESI A2 Quizlet

Correct Answer: B

Rationale: The mass number represents the total number of protons and neutrons in an atom's nucleus. The atomic number represents the number of protons. By subtracting the atomic number from the mass number, we are left with the number of neutrons. Therefore, the correct answer is B: Number of neutrons. Summary: A: Number of electrons - Incorrect, as the mass number minus the atomic number does not give the number of electrons. C: Number of protons - Incorrect, as the atomic number itself represents the number of protons. D: Number of isotopes - Incorrect, as isotopes refer to atoms of the same element with different numbers of neutrons, not the result of mass number minus atomic number.

Correct Answer: C

Rationale: Group IIIA elements have 3 valence electrons, which they tend to lose to achieve a stable octet electron configuration. By losing 3 electrons, they acquire a +3 charge. This is why the correct answer is C. Choice A is incorrect because Group IIIA elements do not typically gain electrons to have a +1 charge. Choice B is incorrect as they don't lose 2 electrons to have a +2 charge. Choice D is incorrect as they do not gain or lose electrons to have a charge of 0.

Correct Answer: D

Rationale: Dispersion forces are the weakest intermolecular force because they are caused by temporary fluctuations in electron distribution, leading to temporary dipoles. These forces exist between all molecules, regardless of polarity. Dipole interactions are stronger as they involve permanent dipoles in polar molecules. Hydrogen bonding is even stronger, occurring between a hydrogen atom bonded to a highly electronegative atom and another electronegative atom. Van der Waals forces encompass both dipole interactions and dispersion forces. Thus, dispersion forces are the weakest intermolecular force among the given options.

Correct Answer: C

Rationale: The correct answer is C: Atomic number. The atomic number represents the number of protons an element has in its nucleus. This is a fundamental property of an element and determines its identity on the periodic table. Atomic mass (A) is the total combined mass of protons and neutrons in an atom. Mass number (B) is the sum of protons and neutrons in the nucleus. Neutron number (D) is the number of neutrons in an atom, which can vary for isotopes of the same element. Therefore, the atomic number is the specific number of protons in an element, making it the correct choice.

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.